Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND METHOD FOR WASTEWATER TREATMENT
WITH ENHANCED SOLIDS REDUCTION (ESR)
S
CROSS-REFERENCE TO RELATED APPLICATION
The present application claims priority under 35 USC
119(e) of U.S. Provisional Application Serial No. 60/238,878,
the entire disclosure of which is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an aqueous waste
treatment method and apparatus that provides improved
treatment of aqueous waste and, more particularly, to a method
and apparatus which employs improved functionality, ease of
operation and aeration techniques to provide improvement in
the treatment of aqueous waste.
Backaround Information
Currently, the processes used in wastewater treatment
plants follow traditional methods that expend energy,
materials and labor at a relatively high rate along with a
large use of land. The high costs associated with traditional
methods of wastewater treatment are due to the treatment,
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handling, and monitoring of all of the wastewater flow's
components with equipment such as pumps, blowers, air
compressors, scrapers, filters, chemicals, heat, presses,
coagulants, flocculants, precipitants and dewatering, among
others. In traditional wastewater treatment systems, the
wastewater is treated using high energy consuming methods.
These methods include, but are not limited to, aerobic
digestion, anaerobic digestion, sludge thickening and solids
dewatering processes. The costs associated with these
treatments amount to approximately 850 of the plant operating
energy budget.
In a typical influent wastewater stream which is subject
to wastewater treatment, 99.90 of the entire wastewater stream
is water and about O.lo is organic, inorganic and dissolved
solids. The typical influent wastewater stream also contains
nutrients in varying concentrations. Nutrients within the
wastewater stream which need removal have an oxygen demand
which must be met for decomposition. In the industry, this
oxygen demand is referred to as biochemical oxygen demand
(BOD). Of the approximately O.lo solids, about loo to 20o are
settleable solids containing about 350 of the BOD. The
remaining 65% of the BOD is contained within the dissolved
organic matter portion of municipal waste. See Figure 13.
In the solids (sludge) handling systems of traditional
wastewater treatment systems, processing energy is expended
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for organic matter to be reduced by digestion to a level of
about 50% reduction in volume while the remaining 50o volume
of organic matter is disposed of by a number of means
including, but not limited to, land fill disposal,
incineration and land application. This results in the
expenditure of additional energy and expense for the handling
of solids. It would be beneficial to have a system and method
which eliminates most of the need for disposal of organic
matter.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide an
apparatus and method for treating aqueous waste containing
organic matter and chemicals.
It is another object of the present invention to use an
activated sludge process with recirculation of a treatment
zone and greater aerator effectiveness to decrease the time
and energy necessary for decomposition of organic matter.
It is yet another object of the present invention to
substantially reduce the wasting of organic matter in the form
of waste activated sludge (WAS) which is the intentional
removal of organic settled solids from the system and thus
reduce the effort and cost of solids handling facilities.
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It is another object of the present invention to provide
an apparatus and method for treating aqueous wastewater which
contains high concentrations of industrial type nutrients.
It is yet a further object of the present invention to
treat municipal waste which has typical concentrations of
chemical oxygen demand (COD), BOD, ammonia and phosphorous.
It is yet a further object of the present invention to
treat industrial strength waste which has high concentration
levels of COD, BOD, ammonia and phosphorous typically found in
animal type wastes.
It is still another object of the present invention to
provide an apparatus and method for pre-treating wastewater
from on-site facilities such as might occur from industrial
manufacturers or animal wastes facilities.
It is another object of the present invention to utilize
an efficient re-circulating aeration system (RCAS), which
provides a combination of aeration, mixing, homogenizing and
shredding that is superior to and which is more affordable
than conventional aeration systems.
It is still another object of the present invention to
provide an apparatus and method which is easier to design,
operate, construct, initialize, manage, expand and maintain
than conventional treatment systems.
It is still another object of the present invention to
provide an apparatus and method which is easier to adapt to
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changes in processing and flow conditions, and which is easier
to automate, monitor and control than conventional treatment
systems.
It is still another object of the present invention to
provide an apparatus and method which when compared with
similar wastewater treatment requirements, uses an overall
smaller footprint (land area) than that which is found with
conventional wastewater treatment plants.
It is still another object of the present invention to
provide an apparatus and method which is more economical to
operate than conventional wastewater treatment systems.
It is still another object of the present invention to
provide an apparatus and method which is less expensive to
build and operate than conventional wastewater treatment
systems.
It is still another object of the present invention to
provide an apparatus and method which increases the ability of
the process vessels to treat larger quantities of wastewater
in aeration basins by not being limited by vessel floor
surface area for placement of diffusers with regard to the
ability to deliver intense aeration.
It is still another object of the present invention to
provide an apparatus and method which provides a significantly
increased decay coefficient (kd).
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It is still another object of the present invention to
provide an apparatus and method which increases the mean cell
residence time (MCRT) beyond that of conventional treatment
systems, thereby providing for increased volatile solids
destruction and subsequent reduced solids handling efforts.
It is still another object of the present invention to
provide an apparatus and method which allows for a highly
flexible food to microorganism (F/M) ratio range above and
below the ratio ranges of conventional treatment systems.
It is still another object of the present invention to
provide an apparatus and method which reduces start-up costs,
which include, but are not limited to, more rapidly increasing
the mixed liquid suspended solids (MLSS) concentration, lower
power costs for initial start-up and reduced costs for hauling
of seed sludge, thereby achieving design flow capacity with
increased efficiency.
It is still another object of the present invention to
provide an apparatus and method which uses cone bottom shaped
vessels for a type of sequential batch reaction system during
start-up conditions for faster initial plant start-up.
It is still another object of the present invention to
provide an apparatus and method which uses cone bottom shaped
vessels for a type of sequential batch reaction that allows
micro colonies to grow rapidly following conditions that have
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upset a process, so as to quickly grow microorganisms which
recover from the upset conditions.
It is still another object of the present invention is to
provide a treatment plant that contains less apparatus and
processes to treat the wastewater to the desired effluent
quality than conventional wastewater treatment systems.
It is still another object of the present invention to
provide a device that separates solids from liquid through
clarification without the need for scraping, raking or
brushing devices in clarifiers.
It is still another object of the present invention to
provide a device which acts as a solids capturing zone which
includes, but is not limited to clarifiers, filtration
structures and optional tertiary treatment systems that
further capture organic matter, and that return the organic
matter to aerobic zones for continued solids digestion.
It is still another object of the present invention to
provide a device which decreases total nitrogen in a waste
stream through oxidation of organic nitrogen into the more
stable compound of nitrate, which is then reduced in the waste
stream by the denitrification process.
It is still another object of the present invention to
provide a device which reduces phosphorous in a waste stream
through microorganism digestion and use for the growing of new
cells in the decomposition of organic matter.
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It is still another object of the present invention to
provide a treatment process that is zone specific and not
vessel specific.
It is still another object of the present invention to
provide a system design that accommodates a specific flow and
specific treatment process.
It is still another object of the present invention to
use the toroidal vortex action of the RCAS system for the
reduction of the number of pathogenic organisms within
wastewater.
It is still another object of the present invention to
provide an apparatus and method which allows for chemical
oxidation of an aqueous solution.
It is still another object of the present invention to
provide a means for the homogenization of a microorganism
colony and the substrate that the colony feeds on.
It is still another object of the present invention to
provide for the disbursements of a large microorganism floc
into a smaller microorganism floc.
It is still another object of the present invention to
cause the entire microorganism floc including the center to
remain aerobic.
It is still another object of the present invention to
provide a high concentration of dissolved oxygen in an aerobic
process.
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It is still another object of the present invention to
provide an alternative to the cost and need for wastewater
lagoons.
It is yet a further object of the present invention to
overcome the deficiencies of known wastewater treatment
systems and methods.
In order to represent the applications for, and
capabilities of, the present invention, raw influent of
municipal wastewater is exampled as the aqueous waste to be
treated. However the embodiments of the apparatus and method
of the present invention can be implemented to treat a variety
of wastes.
The term aeration as it pertains to the present invention
means the addition of a secondary fluid flow (liquid or gas)
into a primary fluid flow (liquid or gas).
The present invention is able to treat organic matter of
wastewater by providing intense aeration by means of an RCAS
(Re-Circulating Aeration System) which gives increased oxygen
transfer efficiencies that results in increased microorganism
oxygen uptake rates and functionalizing, shredding and
homogenizing organic matter causing virtually 100% digestion
of the organic matter. This is a significantly more effective
use of processing energy as compared with traditional
treatment methods using traditional aeration such as diffused
aeration. The present invention also reduces or eliminates
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many traditional energy consuming devices such as primary
clarification equipment, anaerobic digestion equipment,
aerobic digestion equipment, primary treatment lagoons,
incineration furnaces and related equipment, sludge thickening
equipment and sludge hauling equipment.
The present invention enables a more efficient and
complete digestion of organic matter in the wastewater. The
organic matter portions of the wastewater total BOD are
treated in a first aerobic reactor zone and a second aerobic
reactor zone by use of aeration, and in an anaerobic
conditioner zone and anoxic selector zone where the wastewater
is kept in a condition in which the aquatic environment does
not contain sufficient dissolved molecular oxygen for easy
microorganism respiration, which can also be called an oxygen
deficient condition. This oxygen deficient condition
generally refers to an environment in which chemically bound
oxygen, such as nitrate, is present. Aggressive digestion of
the organic matter is accomplished in the zones of the
anaerobic conditioner, first aerobic reactor zone, anoxic
selector and second aerobic reactor zone.
In accordance with one form of the present invention a
process for the treatment of an aqueous solution containing
waste includes the steps of:
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providing an influent wastewater stream to an anaerobic
conditioner zone within which aqueous total solids are
re-circulated, mixed and kept in suspension;
providing low oxygen level mixed liquor suspended solids
from an anoxic selector zone to the anaerobic conditioner zone
to maintain a low dissolved oxygen level within the anaerobic
conditioner zone;
providing an outflow from the anaerobic conditioner zone
to a first aerobic reactor zone, the anaerobic conditioner
zone outflow being mixed in the first aerobic reactor zone
with return activated sludge from a clarification zone whereby
contents of the first aerobic reactor zone are re-circulated
and aerated, and whereby settleable solids present in the
contents of the first aerobic reactor zone are fractionalized,
thereby decomposing and oxidizing the solids and other organic
matter and accumulating insert solids;
discharging the accumulated inert solids from the first
aerobic reactor zone;
providing an outflow of aqueous solution from the first
aerobic reactor zone to the anoxic selector zone wherein the
aqueous solution in the anoxic selector zone is re-circulated
and mixed;
transferring a first portion of the anoxic selector zone
aqueous solution corresponding to the low oxygen level/mixed
liquor suspended solids to the anaerobic conditioner zone, and
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a second portion of the anoxic selector zone aqueous solution
to a second aerobic reactor zone;
recirculating and aerating aqueous solution contained in
the second aerobic reactor zone whereby settleable solids
become fractionalized thereby decomposing and oxidizing
suspended solids and other organic matter;
providing a first portion of the second aerobic reactor
zone aqueous solution to the first aerobic reactor zone;
providing a second portion of the second aerobic reactor
zone aqueous solution to the clarification zone to settle or
separate solids from the aqueous solution contained therein;
providing the settled or separated solids from the
clarification zone, corresponding to return activated sludge,
to the first aerobic reactor zone;
providing aqueous solution of the clarification zone to a
filtration zone to settle or separate solids from the aqueous
solution provided thereto; and
transferring a liquid portion of an outflow of the
filtration zone to a discharge receptacle, and the settled or
separated solids portion of the outflow of the filtration zone
to the influent wastewater stream for re-processing.
In accordance with another form of the present invention,
a process for the biological treatment of an aqueous solution
containing waste to reduce organic material, nitrogen and
phosphorous, includes the steps of:
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providing an influent wastewater stream, which includes
microorganisms, to an anaerobic conditioner zone within which
aqueous total solids are re-circulated, mixed and kept in
suspension, wherein a first stage of luxury phosphorous uptake
is accomplished by regulating a flow of low oxygen level mixed
liquor suspended solids from an anoxic selector zone to the
anaerobic conditioner zone to maintain a low dissolved oxygen
level within the anaerobic conditioner zone;
providing an outflow from the anaerobic conditioner zone
to a first aerobic reactor zone, the anaerobic conditioner
zone outflow being mixed in the first aerobic reactor zone
with return activated sludge received from a clarification
zone whereby contents of the first aerobic reactor zone are
re-circulated and aerated and whereby nitrification occurs and
settleable solids present in the contents of the first aerobic
reactor zone are fractionalized, thereby decomposing and
oxidizing suspended solids and other organic matter along with
enhancing a second stage of luxury phosphorous uptake and
accumulating insert solids;
discharging the accumulated inert solids from the first
aerobic reactor zone;
providing an outflow of aqueous solution from the first
aerobic reactor zone to the anoxic selector zone wherein the
aqueous solution in the anoxic selector zone is re-circulated
and mixed, and causing a low oxygen environment to exist
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within the anoxic selector zone such that denitrification and
release of biological phosphorous occurs along with the
consumption of organic matter contained within the aqueous
solution;
transferring a first portion of anoxic selector zone
aqueous solution corresponding to low oxygen level/mixed
liquor suspended solids to the anaerobic conditioner zone and
a second portion of the anoxic selector zone aqueous solution
to a second aerobic zone, at least the second portion of the
anoxic selector zone aqueous solution being rich in
microorganisms and nutrients;
re-circulating and aerating aqueous solution contained in
the second aerobic reactor zone whereby nitrification occurs
and settleable solids become fractionalized and shredded
thereby decomposing and oxidizing suspended solids and other
organic matter, and further enhancing the second stage of
luxury phosphorous uptake resulting in a consumption of a
large amount of phosphorous by the microorganisms;
providing a first portion of the second aerobic reactor
zone aqueous solution to the first aerobic reactor zone;
providing a second portion of the second aerobic reactor
zone aqueous solution to the clarification zone to settle or
separate solids from the aqueous solution provided thereto;
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providing the settled or separated solids from the
clarification zone to the first aerobic reactor zone as return
activated sludge;
providing aqueous solution of the clarification zone to a
filtration zone to settle or separate solids from the aqueous
solution provided thereto; and
transferring a liquid portion of an outflow of the
filtration zone to a discharge receptacle and the settled or
separated solids portion of the outflow of the filtration zone
to the influent wastewater stream for re-processing.
In accordance with another form of the present invention,
apparatus for the treatment of an aqueous solution containing
waste includes:
an anaerobic conditioner zone fluidly coupled to an
inlet, the anaerobic conditioner zone receiving an influent
wastewater stream through the inlet, the anaerobic conditioner
zone re-circulating the wastewater contained therein such that
aqueous total solids are kept in suspension, the anaerobic
conditioner zone receiving a flow of low oxygen level mixed
liquor suspended solids from an anoxic selector zone to
maintain a low dissolved oxygen level within the anaerobic
conditioner zone;
a first aerobic reactor zone fluidly coupled to the
anaerobic conditioner zone, the first aerobic reactor zone
receiving an outflow of the anaerobic conditioner zone which
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is mixed with return activated sludge received from a
clarification zone whereby contents of the first aerobic
reactor zone are re-circulated and aerated and whereby
settleable solids become fractionalized thereby decomposing
and oxidizing suspended solids and other organic matter, the
first aerobic reactor zone accumulating inert solids, the
accumulated inert solids being discharged from the first
aerobic reactor zone;
an anoxic selector zone fluidly coupled to the anaerobic
conditioner zone and the first aerobic reactor zone, the
anoxic selector zone receiving an outflow of aqueous solution
from the first aerobic reactor zone, aqueous solution within
the anoxic selector zone being re-circulated and mixed, a
first portion of the anoxic selector zone aqueous solution,
corresponding to the low oxygen level/mixed liquor suspended
solids, being provided to the anaerobic conditioner zone;
a second aerobic reactor zone fluidly coupled to the
anoxic selector zone and the first aerobic reactor zone, the
second aerobic reactor zone receiving a second portion of the
anoxic selector zone aqueous solution wherein the aqueous
solution within the second aerobic zone is re-circulated and
aerated whereby settleable solids become fractionalized, a
first portion of the aqueous solution of the second aerobic
reactor zone being provided to the first aerobic reactor zone;
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a clarification zone fluidly coupled to the second
aerobic zone and the first aerobic zone, the clarification
zone receiving a second portion of the second aerobic reactor
zone aqueous solution, whereby settling or separating and
S capturing of solids from the aqueous solution occurs, and the
settled solids, corresponding to return activated sludge, are
provided to the first aerobic reactor zone; and
a filtration zone fluidly coupled to the clarification
zone, the inlet, and an outlet, the filtration zone receiving
an outflow from the clarification zone to separate solids from
the liquid portion of the contents of the clarification zone,
a first portion of the contents of the filtration zone, which
corresponds to effluent, being provided to the outlet, and a
second portion of the contents of the filtration zone, which
corresponds to separated solids, being provided to the inlet
and being combined with the influent wastewater stream for
re-processing.
These and other objects, features and advantages of the
present invention will become apparent from the following
detailed description of preferred embodiments which is to be
read in connection with the accompanying drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a graph showing the relative concentrations of
biomass, soluble organic food and total oxygen uptake vs. time
of various wastewater treatment processes;
Fig. 2 is a graph showing the rate of metabolism vs. F/M
(Food to Microorganism) ratio of wastewater treatment
processes;
Fig. 3 is a chart showing comparative data for a variety
of wastewater treatment systems;
Fig. 4 is a schematic diagram of an eight-vessel plant
layout according to the preferred embodiment of the present
invention showing flex-flow, nitrification, de-nitrification
and phosphorous reduction;
Fig. 5 is a schematic diagram of an eight-vessel plant
layout according to an alternate embodiment of the present
invention;
Fig. 6 is a schematic diagram of a seven-vessel plant
layout according to an alternate embodiment of the present
invention showing specific flow characteristics of plug flow,
nitrification, de-nitrification;
Fig. 7 is a schematic diagram of a six-vessel plant
layout according to an alternate embodiment of the present
invention showing specific flow characteristics of plug flow
and nitrification;
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Fig. 8 is a schematic diagram of an eight-vessel plant
layout according to an alternate embodiment of the present
invention showing specific flow characteristics of step feed,
nitrification, de-nitrification and phosphorous reduction;
Fig. 9 is a schematic diagram of a seven-vessel plant
layout according to an alternate embodiment of the present
invention showing specific flow characteristics of step feed,
nitrification and de-nitrification;
Fig. 10 is a schematic diagram of a seven-vessel plant
layout according to an alternate embodiment of the present
invention showing specific flow characteristics of step feed
and nitrification;
Fig. 11 is a schematic illustration of a wastewater
treatment system made up of a number of treatment zones, each
of which includes a number of vessels;
Fig. 12 is a schematic illustration of a vessel structure
of the present invention, including a zone flow diagram;
Fig. 13 illustrates the solids composition of raw
influent in typical municipal wastewater;
Fig. 14 shows a wastewater nitrogen cycle;
Fig. 15 is a schematic illustration of the Re-Circulation
Aeration System (RCAS) with an optional aerator by-pass;
Fig. 16 .is a chart showing the 30 minute solids settling
as related to MCRT;
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Fig. 17 illustrates how the Decay Co-efficient kd is
calculated in relation to the MCRT and F/M Ratio; and
Fig. 18 is a simplified representation of the process
shown in Fig. 5 with a filtration zone coupled to the
clarifiers for returning captured solids for reprocessing.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Treatment of chemical and biological aqueous waste can be
performed through utilization and implementation of the method
and apparatus of the present invention. The present invention
cleans aqueous wastes in an aqueous solution by means of
various strictly aerobic treatment methods and combinations of
treatment methods such as aerobic biological decomposition,
biological oxidation, chemical oxidation and physical
separation of solids. The present invention is efficient in
its use of aerobic treatment methods in that there is a
reduction in the reliance on chemicals for nutrient removal.
These methods exist in various stages of stabilization within
the treatment process.
The approximate levels of performance (influent vs.
effluent) within the treatment process of the present
invention are as follows:
Reduction of 90o to 99.50 influent total BOD (biochemical
oxygen demand) concentrations through oxidation and subsequent
gravity settling.
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Reduction of organic nitrogen through oxidation into
first ammonia, second nitrite and third nitrate.
Reductions of 95% to 99.5% influent ammonia nitrogen
concentrations through nitrification.
Reductions through de-nitrification of 50% to 99.5%
nitrite and nitrate nitrogen concentrations that have resulted
through the nitrification process referenced above.
Reduction of 90% to 99.5% influent total phosphorous
concentrations through luxury "P" uptake.
Destruction of up to 99.5% total organic suspended solids
concentrations through intense oxidation.
The following description explains the processes of the
present invention that achieve these levels of performance as
the aqueous solutions proceed from process zone to process
zone for treatment. The design of the present invention
prefers a total hydraulic detention time for nutrient
oxidation within the processing zones of about 4 to 8 hours.
PROCESS PERFORMANCE
Treatment of chemical and organic matter that occurs as
an aqueous waste is stabilized through either oxidation or
biological means. Stabilization is actually a group of
processes. For example, in the treatment of municipal
wastewater, the stabilization of ammonia as it is converted
into nitrogen gas is a several step process. Ammonia (NH3) is
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biologically oxidized into nitrite (N02) and then it is
organically stabilized into nitrate (N03). The next and final
stage is known as de-nitrification. Once this stage is
attained, the presence of oxygen is reduced to very low levels
and the elemental bound oxygen in the form of N03 is utilized
for respiration while the nitrogen gas, N2, is released into
the atmosphere.
Another form of treatment is oxidation of chemical
compounds which is accomplished by aeration. The reaction
occurring from oxidation causes a chemical element or compound
to lose electrons. This loss of electrons makes the element
or compound more stable.
Biological treatment is one of the most important steps
in processing municipal wastewater, and a brief explanation of
that treatment is helpful in understanding the present
invention and its apparatus and processes. During biological
treatment, microorganisms eat, convert or consume nutrients
(BOD) in the wastewater. These nutrients can be biodegradable
organics or chemical in nature. With traditional systems,
physical treatment of raw wastewater by sedimentation and
wasting removes only about 350 of the BOD, due to the high
percentage (about 650 of the BOD) of BOD contained in the non-
settleable and dissolved solids contained in wastes. The
present invention uses aerobic digestion treatment through a
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suspended growth treatment method to treat the total BOD
within the aqueous solution to levels at or above 95% removal.
There are two types of solids in liquid wastes, 1)
organic, and 2) inorganic. Inorganic solids do not break down
or decompose by biological treatment. Therefore, as the
inorganic or inert solids begin to accumulate in the
processing system, the removal or wasting of inert solids
should occur. This wasting is set on a predetermined
concentration ratio of inert to organic solids. With the
percentage of inorganic or inert solids content in most
municipal type wastewater being small compared to the entire
solids load entering the system, the time frame for inert
wasting could range substantially between 90 days and 360 days
or more. Organic solids content of the typical municipal waste
stream makes up approximately 70o to 85% of the solids in the
wastewater. Around 80o to 85% of these solids are typically
dissolved solids and are not settleable, but 15o to 200 of
these solids are settleable. However, these settleable solids
are shredded during the recirculation process of each of the
aerobic processing zones used in the present invention which
allows for easier consumption by the microorganisms.
This shredding enhances the aerobic digestion treatment
process of the current invention by allowing the microorganism
colony and settleable solids to become homogenized. This
homogenization of settleable solids causes all of the food
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substrate to become almost a dissolved solid allowing for
easier consumption by the microorganism colony.
As the floc of the microorganism colony passes through
the RCAS system of the present invention, the large floc
portions are disbursed into smaller floc particles. The
reduction in floc size aids the consumption of substrate by
the microorganism colony by increasing the surface area of the
floc and causing more intimate contact with needed food and
oxygen.
Digestion of a substrate and microorganism colony occurs
with increased speed when a microorganism colony remains
aerobic throughout its contents. The RCAS system increases
the digestion of a substrate by keeping microorganism colonies
in disbursed small floc particles so as to maintain an aerobic
condition in the center of the floc particles. As the floc
particles become smaller, the concentration of dissolved
oxygen within the aerobic zone is easily accessible to the
center of the floc particles. This also allows for a high
concentration of dissolved oxygen to be maintained within an
aerobic zone.
The processing and aerobic digestion treatment system of
the present invention are provided by living systems that rely
on mixed biological culture to break down the organic wastes.
The present invention's aerobic digestion treatment system
grows and maintains in suspension a high population of non-
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photosynthetic microorganisms, i.e., a biomass, which consumes
the organic waste. Under aerobic digestion conditions, the
reduced organic compounds are oxidized to end products of
carbon dioxide and water.
The growth and survival of non-photosynthetic
microorganisms depends on the microorganisms ability to obtain
energy by metabolizing the organic matter. A traditional
aerobic treatment process results in complete metabolism and
synthesis of organic matter, producing biological growth in
large quantities which must be removed from the system to keep
the process from becoming biologically overloaded compromising
the quality of the effluent. The present invention makes use
of a complete aerobic digestion treatment of the biomass with
which the microorganism environment is kept to the far right
of the "endogenous respiration phase" of Fig. 2 by controlling
and balancing the F/M (food-to-microorganism) ratio (in a
range of .05 to .80) and the oxygen delivery. This results in
not only the complete metabolism and synthesis of the organic
matter but also in the significant reduction of biological
solids at the end of the process.
Another feature of the present invention is the use of
the nitrification cycle for the conversion of large amounts of
organic nitrogen into ammonia, ammonia into nitrite and
nitrite into nitrate. The nitrate is then de-nitrified
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releasing nitrogen into the atmosphere, resulting in a
reduction of total nitrogen within the waste stream.
Still another feature of the present invention is the
consumption of phosphorous entering the system by
microorganisms as a food source for cell wall development and
new cell growth during high oxygen concentration times such as
that which occurs in the aerobic reactor zones.
Referring now to Fig. 1, the characteristic growth
pattern for microorganisms is shown where the relative biomass
concentration (on the vertical axis) is charted as a function
of time (on the horizontal axis). After a short time period
for adaptation to the new environment, the microorganisms
consume the organic matter and reproduce by binary fission,
exponentially increasing the number of viable cells and
biomass in the culture medium. This is the "log growth phase"
shown in the left most portion of the chart in Fig. 1. The
rate of metabolism in the "log growth phase" is limited by
both the ability of the microorganisms to process the organic
matter, and the amount of dissolved oxygen available to the
microorganisms for respiration.
The "declining growth phase" shown in Fig. 1 is caused by
an increasing shortage of the organic matter necessary for
growth of the microorganisms. In the "declining growth
phase", the rate of reproduction of the microorganisms
decreases. The growth of microorganisms in the "declining
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growth phase" is a function of both the concentration of the
microorganisms and concentration of the growth-limiting
organic matter.
The "declining growth phase" is followed by a "stationary
phase". In the "stationary phase", the biomass concentration
reaches a maximum value, and the low concentration of
remaining organic matter substantially limits the biomass
growth rate which becomes relatively constant.
The "endogenous respiration phase" follows the
"stationary phase". In the "endogenous respiration phase",
viable microorganisms compete for the small amount of organic
matter which is still in the wastewater that is undergoing
treatment. Eventually, starvation of the microorganisms
occurs, such that the rate of death exceeds the rate of
reproduction. Thus, the concentration of biomass in the
aqueous solution declines during the "endogenous respiration
phase". In the current invention the endogenous respiration
(ER) is controlled such that the rate of death of the
microorganisms is equal to the rate of growth of the
microorganisms as verified by a mixed liquid suspended solids
(MLSS) concentration that is kept at a constant concentration
relative to the processing criteria.
Wastewater treatment according to the present invention
will now be described in detail. In the present invention,
wastewater treatment processing takes place in three stages:
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(1) Mass biological aerobic digestion to consume the
organic waste, including but not limited to total
organic nitrogen and total phosphorous reductions;
(2) Solids capturing zone clarification/sedimentation;
and
(3) Re-treatment of solids capturing zones settled
solids by returning solids back to the aerobic
reactor process.
In the processing method of the present invention,
consumption of organic waste is accomplished by maintaining an
environment consisting of high mean cell residence time
(MCRT), a moderate food to microorganism (F/M) ratio and
intense aeration, wherein the microorganisms are forced to
live in the endogenous respiration phase.
The clarification/sedimentation stage of the process is
used to separate solids from the supernatant (the remaining
liquid) through gravity settling. Once the aqueous solution
containing suspended solids enter the clarification zone
(vessels 76, 80, 84 and 88 corresponding (Clarifier #'s l, 2,
3 and 4 of Fig. 4) from the aerobic reactor zone #2 (vessel 20
of Fig. 4), the specifics of which are explained in detail
below, the velocity of the supernatant is slowed to allow the
solids to settle by gravity. As the settled solids slightly
concentrate at the bottom of the clarification vessels, they
are frequently and quickly removed and sent back to vessel
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aerobic reactor #1 zone (vessel 18) for further treatment.
The supernatant (clearer aqueous solution) continues through
the process where it may be further treated with optional
tertiary treatments such as tertiary clarification or
filtration for the nearly complete removal of biological and
inert matter before being discharged. A receiving stream,
evaporation ponds, landscape irrigation, crop irrigation or to
some other type of disposal may be the recipient of such a
discharge.
Aerobic digestion treatment systems such as that of the
present invention must grow and maintain in suspension a
population of microorganisms in order to consume the organic
waste. Although, as illustrated in Fig. l, individual
microorganisms grow rapidly, it takes time at startup or where
major load changes are occurring to increase the original low
concentration of microorganisms to levels high enough to
rapidly degrade the organic waste. It therefore becomes
important to use methods for increasing the concentration of
MLSS in a rapid fashion. Plant startup time, in regard to
traditional systems, range as long as 30 to 45 days for MLSS
concentrations to reach acceptable operational levels. Using
the present invention, plant start-up time can be reduced to
as little as 14 days or less with the present invention. The
time required for plant re-starts due to a toxic shock load to
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the microorganisms are reduced as compared with traditional
plant time requirements. These methods are discussed below.
A common design concept for aerobic digestion systems is
mean cell residence time (MCRT), which is the average time the
microorganisms spend in the system. The MCRT of traditional
treatment systems relates to the quantity of microbial solids
in an activated sludge process, relative to the quantity of
solids lost in the effluent and the excess solids withdrawn
from the processing cycle in the waste sludge. With the
present invention the MCRT relates to the quantity of
microbial solids in the aerobic treatment process, relative to
the quantity of solids lost in the effluent only, which is un-
intentional wasting, as there are virtually no volatile solids
withdrawn as waste activated sludge. Typical MCRT values for
traditional systems are from 15 to 30 days. However, MCRT
values for the present invention begin at 30 days and reach
numbers of 150 to 250 days or greater (see Fig. 3). MCRT
values for conventional aerobic treatment systems of greater
than 30 days may produce operational problems. The excessive
build up of solids in the system caused by inadequate wasting
of solids is a common cause of a poor effluent quality due to
the retention of higher concentrations of suspended solids,
turbidity, etc. Other reasons for poor effluent quality
include extremely old slow settling solids, over-oxidation of
the solids and de-flocculation of the solids. Consequently,
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for traditional aerobic treatment systems it is desirable to
intentionally waste excessive solids from time to time to keep
the MCRT within the ranges shown in Fig. 3. As in the present
invention, the removal of excessive solids is not necessary
due to its ability to nearly complete the digestion of all
organic solids.
Quantities of solids are expressed as concentrations of
MLSS (mixed liquid suspended solids) with values for a
conventional system shown in Fig. 3. These typical MLSS
values for conventional systems range from 1,000 mg/L at the
low end of the range for contact stabilization systems to
6,000 mg/L for complete mix and extended aeration systems.
The quantity of microbial solids (MLSS) in the anaerobic
conditioner zone, anoxic selector zone and aerobic reactor
zones of the present invention (see, e.g. Fig. 4 explained in
detail below) range from 2,000 - 8,000 mg/L or more. The
apparatus and method of the present invention is able to
maintain the MLSS concentrations shown in Fig. 3 for near
complete digestion of organic matter of a typical municipal
type waste, to the elevated MLSS concentration shown in Fig. 3
for near complete digestion of organic matter of non-typical
industrial type waste by using an efficient aeration delivery
system device such as the one used in the present invention
(re-circulating aeration system or ~~RCAS"). The aeration
device used in the present invention is the one described in
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USP 5,893,641 (Garcia), the entire disclosure of which is
incorporated herein by reference.
The process implemented by the present invention also
achieves the results of total organic solids digestion by
using the above-mentioned efficient aeration delivery system
(RCAS) to deliver atmospheric air necessary for oxygen
transfer, circulation, homogenization and deep mixing. An
additional benefit of the implemented process that uses an
aeration system of the type mentioned above is the mixing and
secondary oxygenation of the MLSS residing within the aerobic
reactor zones. This mixing and secondary oxygenation is
accomplished by the removal of the MLSS contents from the
aerobic reactor zones at their lowest point and discharging
the re-oxygenated MLSS back into each respective vessel at an
elevation of substantially two thirds of the way below the
surface of the side water depth. The secondary oxygenation of
the MLSS is accomplished by allowing the excess entrained air,
injected by the RCAS, carried along with the aerated MLSS to
flow via a conduit into and through the contents of the
aerobic reactor zones. The primary and secondary oxygenation
of the aerobic reactor zones MLSS enables the dissolved oxygen
(DO) concentration to achieve levels in a range substantially
between 3.0 and 5.0 mg/L. The dissolved oxygen concentration
in the aerobic reactor zones is kept at an operational level
that exceeds the upper range for traditional aerobic digestion
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systems, which is 2.0 mg/L. For this reason, inter alia, the
present invention achieves a higher degree of organic solids
digestion through its efficient oxygenation treatment process.
With the higher than normal dissolved oxygen
concentrations and intimate mixing as achieved with the
present invention, a higher rate decay co-efficient (k~) of
organic matter occurs than is achieved with traditional
aeration systems. The word "decay" is the term used to
express destruction (digestion) of volatile (organic)
suspended solids in the formula relating F/M to MCRT.
Traditional aeration systems have a kd value of between 0.04 to
0.06 for an average of 0.05, whereas in the present invention,
kd is substantially 0.10 or twice that for traditional aeration
systems, thus yielding a greater digestion rate. See Fig. 17
for the formulas used for determining the decay co-efficient.
Traditional oxygen transfer efficiency is expressed as
the percentage of mass of oxygen that reaches the biological
cell compared to the applied mass of gaseous oxygen supplied
to the reactor. The rate of oxygen transfer from air bubbles
admitted by the RCAS is a function of several factors which
vary according to the wastewater characteristics, including
but not limited to, the oxygen transfer coefficient of the
wastewater within a conduit and the oxygen transfer
coefficient within a vessel, the oxygen saturation coefficient
of the wastewater, and the present dissolved oxygen
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concentration and saturation concentrations of oxygen within
the aqueous solution.
In a traditional aerobic biological treatment system the
metabolism of organic matter in the wastewater results in an
increased biological mass (growth) of microorganisms in the
system. Excess microorganisms are removed or wasted from the
system to maintain a proper balance between food supply and
the mass of microorganisms that exist in the aeration basin
where the oxygen is being delivered. This balance is referred
to as food-to-microorganism (F/M) ratio. One familiar in the
art knows that an F/M ratio of 0.05 to 0.20 that is maintained
in traditional aeration basins defines the operation of
extended aeration systems. Fig. 2 illustrates how an
increasing F/M ratio affects the rate of metabolism. Although
the "exponential growth phase" shown in Fig. 2 is desirable
for maximum rate of removal of organic matter, in this phase
the microorganisms are in dispersed growth and experience
difficulty in settling out of solution by gravity. Moreover,
there is excess unconsumed organic matter in solution, which
cannot be removed by a dispersed growth microorganism colony
of a traditional aeration system and thus passes out of the
system in the effluent. Operation of traditional aeration
treatment systems at a high F/M ratio thus results in
inefficient and insufficient BOD removal.
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At a low F/M ratio, the overall metabolic activity in the
aeration basin is endogenous. In this phase the metabolism of
the organic matter is nearly complete and the microorganisms
flocculate rapidly and settle out of solution by gravity.
Operation in the endogenous phase is desirable where a high
BOD removal efficiency is desired.
Typical traditional aeration treatment systems F/M ratios
range from 0.05 to 0.2 for the low rate needed for extended
aeration, 0.2 to 0.4 for conventional rate of treatment to the
upper range of 0.4 to 1.5 for high rate treatment. However, in
the present invention, the F/M ratio is kept in the range of
0.05 to 0.8 to encompass all of the low rate, all of the
conventional rate and a portion of the high rate treatment
processes allowing for a significant amount of flexibility
within a single treatment plant design. This flexibility is
evident in that as the flow of a treatment system increases
and the concentrations of organic matter remains the same, the
recirculation rate is able to be increased by simply
modulating the aerator to increase the speed of the
recirculating pumps, which in turn increases the aeration
delivery rate. Therefore, with a sufficient amount of
available oxygen as achieved by using an aeration delivery
system such as the one described herein and in USP 5,893,641,
the ranges of F/M ratio listed above for the current invention
allow the microorganisms not only to completely metabolize the
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organic matter, but through intense aeration the food source
diminishes as the microorganisms consume it and thus the
competition for food increases. Microorganisms consume
themselves and each other in order to survive as in the
endogenous respiration treatment process, even at the higher
F/M ratio of 0.8. The long-term cannibalistic state of
endogenous respiration ensures the mass reduction of solids
accumulation that occurs with the aerobic digestion process of
the current invention. Maintaining F/M ratios such as with
the current invention along with maintaining high amounts of
dissolved oxygen as is economically possible using the
aeration device and delivery system mentioned above, the
oxidation of organic matter is rapidly completed.
As the MCRT of the microorganisms increases, the
promotion of rapid settling of the microorganisms increases,
benefitting the clarification process, as shown in Figs. 2 and
16.
In order to better understand the term "wasting" as used
in the present invention, the following explanation is given.
As the concentration of inert solids increases, a removal or
wasting of these solids should occur so as to allow a
sufficient volume of biological microorganisms to reside
within the biological processing zones. For this reason
provisions have been made for the removal of inorganic or
inert solids from aerobic reactor #1 as illustrated in figures
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4, 5, 6, 7, 8, 9, 10 and 18. When the inert concentration
reaches the removal level a predetermined amount of solids are
removed. The concentration of inert solids prior to this
wasting has steadily risen from the extremely low
concentrations (approximately O.OOlo of the settleable solids
as indicated in figure 13) in the influent flow, to levels
that can reach substantially 50% of the total solids
concentration residing in the biological processing zones.
While there are organic solids intermixed with inert solids,
the total weight of organic solids wasted out of the
biological processing zones are substantially between O.Ols
and 0.5o as compared to the total weight of organic solids
that have entered the biological processing zone. This
wasting of inert and organic solids should continue
periodically until the inert solids concentrations within the
biological processing zone have dropped to acceptable
processing levels.
Clarification may be defined as separating the biomass
from the treated aqueous solution. Traditional aerobic
treatment and solids separation systems attempt to retain the
bulk of the microorganisms in the system by coagulation and
flocculation, however, wasting occurs due to the nature of
traditional process and apparatus along with operational
energy cost limitations. The biological solids then settle to
the bottom of a clarifier. The majority of the biological
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solids are then returned to the aeration basin while
intentionally wasting (removing) from the system a portion of
the biological solids (activated sludge), which is an amount
of activated sludge that exceeds the system's designed
treatment digestion ability. The current invention retains the
microorganisms in the system by settling the biological solids
along with all inorganic solids in a clarification zone
(Clarifiers #1, 2, 3 and 4 of Fig. 4), and returning them to
the aerobic reactor #1 zone (vessel 18 of Fig. 4) for further
processing. Care is taken so as to regulate the blanket depth
(accumulated sludge in the bottom of a clarifier) to a minimum
by the frequency and number of gallons of return activated
sludge (RAS) evacuated and returned to the aerobic reactor #1
zone. This frequency of evacuation of RAS eliminates long
IS detention times of biological solids in the clarification
zone, which would otherwise become septic, gasify and float to
the surface of the clarification zone. Observation and
adjustments are made to the evacuation of RAS flows so as to
minimize the hydraulic velocities in the clarification zone.
Higher hydraulic velocities can cause inefficient settling in
the clarification zone resulting in biological solids carry
over in its effluent.
With the present invention, the hydraulic detention time
within the aeration cycles are in the ranges of the complete
mix and plug flow processes, and partially in the high purity
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oxygen process range, while deriving the benefits of the
extended aeration process. The extended aeration process
typically uses 18 to 36 hours to almost completely oxidize
(treat) organic matter as shown on Fig.3 (see the right-most
column thereof). The present invention obtains the same
results on the organic matter in substantially 4 to 8 hours
time. By using an efficient aeration delivery system, the
current invention drastically reduces the time needed to
oxidize the organic matter. This is accomplished by the
aeration delivery systems located at each of the aerobic
reactor zones (vessels 18, 20 of Fig. 4), the anaerobic
conditioner zone (vessel 8 of Fig. 4) and the anoxic selector
zone (vessel 58 of Fig. 4) re-circulating, by volume, each of
their respective contents substantially 1000 every two hours.
When combining the anaerobic conditioner zone along with both
aerobic reactor zone and the anoxic selector zone
recirculation percentage rates, the total processing
recirculation percentage rate is equal to or greater than 200%
of the influent flow entering the treatment process in a 24
hour period. The aeration system re-circulates, shreds and
homogenizes the organic matter and microorganisms, and
oxygenates the entire mass many more times than traditional
systems resulting in a greater biological solids digestion
rate in a shorter time period than traditional systems.
Typical re-circulation rates in conventional treatment systems
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range from 25 to 100 percent per day of the influent flow for
complete mix systems, 25 to 50 percent per day of the influent
flow for plug flow systems and 75 to 150 percent per day of
the influent flow for extended aeration systems.
Recirculation percentage rates as they pertain to traditional
activated sludge treatment systems refer only to the
percentage of recirculation of the Return Activated Sludge
(RAS) as compared to the influent flow. While the present
invention uses this same type of RAS recirculation percentage
the present invention also utilizes the previously described
processing recirculation percentage achieving a greater solids
digestion rate than is possible with traditional activated
sludge treatment systems.
The biological treatment technique according to the
present invention will now be described. The composition of
microorganism cells consist of 70 to 90 percent water with 10
to 30 percent dry material by weight. Of this dry material,
70 to 95 percent is organic and 5 to 30 percent is inorganic.
Ninety-five percent of the organic dry material consists of
carbon, oxygen, nitrogen, hydrogen and phosphorus, and other
trace materials respectively. The present invention takes
advantage of the large percent of organics available to the
microorganisms by maintaining an extremely long MCRT for not
only the complete oxidation of organic compounds but also for
the consumption of biomass (the mass of organic material
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consisting of living organisms feeding on the wastes in the
wastewater, dead organisms and other debris), which also
contains these same
elements. In the activated sludge process, carbon, oxygen,
nitrogen and hydrogen are used as the main constituent of
cellular material, with phosphorus being used as the
constituent of nucleic acids, phospholipids and nucleotides.
Compounds are taken up by microorganisms from their
environment to carry out two basic primary metabolic
activities: energy production through bioenergetics, and
synthesis of new cell material through biosynthesis.
Microorganisms produce energy for themselves from light,
organic and inorganic compounds. The main inorganic compounds
used by the microorganisms as a source of energy are, ammonium
(NH4) , nitrite (N02) , dissolved sulfide (HZS) , and elemental
sulfur. These compounds are oxidized and the energy released
is used for cell maintenance, synthesis of new cell material
and movement of the microorganism if they are mobile. There
are two types of microorganisms: autotrophic microorganisms
which use inorganic carbon for biosynthesis and heterotrophic
microorganisms which use organic carbon for biosynthesis.
Carbon makes up approximately SO percent of the dry mass
of the microorganism cell. Therefore carbon is the main
element used during biosynthesis. The microorganisms use as
one of their sources of energy for new cell development either
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organic compounds such as fatty acids, amino acids, sugars,
organic acids, or carbon dioxide (C02). Through biological
processes, organic carbon is converted into microorganism
biosynthesis material and gases such as carbon dioxide, which
can escape into the atmosphere. Through the 200%
recirculation by volume of the contents of the aerobic reactor
by the RCAS of the present invention, the microorganisms are
enabled to come into contact with their carbon source more
times and more efficiently than in traditional systems.
Oxygen and hydrogen are the main gas elements used in
cellular material. The source of oxygen for the cellular
material of microorganisms is found in molecular oxygen,
organic compounds or even carbon dioxide. The present
invention delivers oxygen through the aerobic reactor's
aeration delivery system (RCAS) directly into the aqueous
solution of nutrients and microorganisms. This offers the
microorganisms the opportunity to respirate in the easiest
manner and with the most available oxygen source for
bioenergetics and biosynthesis. The source of hydrogen for
the cellular material of microorganisms is found in molecular
hydrogen and organic compounds. Oxygen as an electron
acceptor is used in the classification of microorganisms.
Microorganisms, which use oxygen are referred to as aerobes,
and those that do not use oxygen are referred as anaerobes.
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The present invention uses aerobes for organic compound
stabilization and decomposition in the aerobic reactor.
Nitrogen is the major source for proteins and nucleic
acids for the microorganisms and includes 14 percent of the
cellular material. Microorganisms can use inorganic nitrogen
in the form of nitrogen gas (Nz) , ammonia-nitrogen (NH3 + NH4) ,
nitrite (N02) and nitrate (N03). Nitrogen gas to be used must
first be converted into ammonium (NH9) and then converted into
organic nitrogen as in nitrogen fixing in soils, however
ammonia-nitrogen (NH3) can be considered as 100 percent ready
and available for nutritional use by microorganisms.
Conversion of ammonia (NH3) into nitrite (N02) and nitrate
(N03) opens the door for microorganisms that use NOZ and N03 as
their sole nitrogen source. However there is a large amount
of energy needed for microorganisms to be able to use this
nitrogen as a source for growth. These microorganisms must
oxidize larger amounts of organic compounds to have the energy
needed for using NOZ and N03 as their nitrogen source. This
results in a lower microorganism growth rate than when using
NH3 as a source for nitrogen. The current invention uses this
lower growth rate to its advantage when maintaining an
extremely long MCRT and variable F/M ratio to reduce the
amount of microorganism growth. In combination, the
microorganisms must consume greater amounts of organic
compounds and are unable to reproduce as rapidly. There are
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three biological removal processes used to remove nitrogen,
they are ammonification followed by nitrification and
denitrification. Ammonification and nitrification occur in
the aerobic reactors while denitrification occurs in the
anoxic selector. Ammonification is carried out by
heterotrophic microorganisms, which take organic nitrogen in
the form of proteins and peptides and decomposes them into
ammonia and ammonium. Autotrophic microorganisms that convert
ammonia into NOZ and then N03 carry out nitrification. The
third stage in the process is denitrification where another
group of heterotrophic microorganisms reduce the N03 to NOZ and
then to NO and finally to NZ for release into the atmosphere.
Microorganisms use phosphorus during cell synthesis, cell
maintenance and as energy transport. Due to this, about 10 to
30 percent of an influent's phosphorus is consumed by
microorganisms and used for their metabolic processes.
However there are three microorganisms with the ability to
store phosphorus in larger amounts than is needed for growth
requirements. This is referred to as luxury phosphorus
uptake. The three microorganisms, acinetobacter, pseudomonas
and moraxella, are collectively referred to as poly-P bacteria
because of their ability to store phosphorus in the form of
polyphosphate granules. The poly-P bacteria are able to use
the polyphosphate as an energy source when under stressed
conditions. Since these bacteria are only able to store this
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extra amount of phosphorus when under aerobic conditions, the
current invention maintains dissolved oxygen in sufficient
quantities to ensure luxury phosphorus uptake within the
aerobic reactor zones. The present invention uses an
anaerobic conditioner zone as an area for microorganisms to
reach the necessary stressed conditions to enable these poly-P
bacteria to use the polyphosphate as energy, thus reducing the
amount of phosphorus in the effluent stream.
In summary, carbon, nitrogen and phosphorus are reduced
through bioenergetics and biosynthesis by the microorganisms.
The amount of removal of these nutrients is directly related
to the concentration of the nutrients and the amount of time
these nutrients are exposed to microorganisms. Increasing the
number of times nutrients come into contact with the
microorganisms and oxygen through homogenization, as is the
case with the current invention, can accelerate the organic
digestion process. By designing zones to substantially meet a
2-hour hydraulic detention time and by re-circulation and re-
aerating the entire content, by volume, of the aerobic reactor
zones 1000 every 2 hours before it flows out of the zones, an
environment for the microorganisms to accelerate the
biological digestion process is provided. All biological
solids removed from the solids capturing zone and returned to
the processing zones are subject to this accelerated
biological digestion as well. The present invention, as
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outlined above, produces this effect, and henceforth utilizes
a smaller footprint design as compared to traditional
treatment systems while performing as if there is more
hydraulic detention capacity available.
By using an extended MCRT, a flexible F/M ratio and
increasing the re-circulation as described above, the
consumption of biomass also occurs, achieving an enhanced
organic solids reduction in the process through digestion.
Only after a predetermined concentration of inorganic solids
is reached is intentional wasting initiated of substantially
only those inorganic solids, with possible high concentrations
of phosphorous.
Another component of the ~~enhanced solids reduction"
(ESR) wastewater treatment system of the present invention are
the zones (vessels), as being a part of an entire system. The
zones consist of a vessel or group of vessels, which contains
the wastewater for treatment. These vessels are preferred to
be of a particular shape consisting of a vertical cylinder
having a conical bottom. However, the processing of said
wastewater with the present invention is not limited to the
preferred vessels. Effective treatment with the process of
the present invention is attainable in square or rectangular
vessels, with flat or sloped bottoms. The zones are unique to
the process designated for that zone. The vessel design and
construction of the process zones are a component of the ESR
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wastewater treatment system that permits the modularization of
the system. The zones illustrated in Fig. 4, the preferred
apparatus embodiment, are of a single vessel per zone design.
Alternate apparatus embodiments could resemble a zone having
one or more vessels performing the unique process function of
that zone. Alternately, as an example of a large capacity ESR
wastewater treatment system, the number vessels shown in
Fig. 11, could be classified as one zone, and additional
modules resembling the number of vessels in Fig. 11 could be
added for each additional treatment zone required until such
time that the design criteria of a large volume treatment
plant is satisfied. Alternate designs could incorporate
various sized vessels that utilize the same treatment
processing techniques as described herein.
Vessel design incorporates the vertical cylinder with a
depressed-shaped bottom, but preferably cone-shaped bottom
(see Fig. 12) in order to create the environment to enhance
the desired path of the wastewater stream during treatment.
The use of the cone bottom vessel is essential for the
settling and concentrating of solids within the clarification
zone and is used effectively in the process zones in the
settling and concentrating of phosphorous rich inorganic
solids for periodic removal. Keeping solids in suspension is
accomplished by the RCAS system as it receives flow into the
pump from the bottom of the aerobic reactor zone. The aerobic
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reactor zone contents are then pumped, aerated and
recirculated, generating velocities during the RCAS conduit
discharge back into the aerobic reactor so that the aerobic
reactor zone contents are well mixed.
$ With the use of cylindrical shapes during clarification,
and with the prompting of flow via the inflow's direction and
its positioned reference point, and the re-circulation
discharge direction and its positioned reference point, the
wastewater is directed to travel in a particular direction,
preferably rotational, at a particular speed and for a
particular distance so as to allow the settling solids to
arrive at the lower portion of the vessel, and remain within
the vessel for a particular period of time so as to
accumulate, concentrate and process, in order to facilitate
1$ the treatment desired. The conical bottom along with the flow
characteristics of the traveling wastewater, promotes the
settling solids to accumulate at a central point of reference
at the lowest point within the cone shaped bottom (referred to
as solids concentrator). These accumulated settled solids are
then available to be evacuated by way of a port exiting at
that lowest point.
The embodiment of Fig. 4 is utilized to illustrate the
preferred flow characteristics when the influent contains
normal BOD, TSS (Total Suspended Solids) & NH3 loading, and
2$ requiring normal nitrification, denitrification and
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phosphorous reduction, as demonstrated by the influent
concentrations of a municipal wastewater treatment plant. In
Fig. 4, pre-screened influent wastewater containing suspended
solids and biodegradable organic substances passes through the
influent feeder line, which flows into an influent splitter
box, which then has take-off feeders to each of the vessels.
This enables Fig. 4 to represent a universal configuration
that would be used as a representative for all possible flow
characteristics sought after for varying treatment
specifications.
FLOW AND PROCESSES
Referring now to Fig. 4, a preferred embodiment of the
enhanced solids reduction (ESR) wastewater treatment system in
accordance with the present invention is shown which provides
complete operational flexibility in the processing
characteristics of nitrification, de-nitrification and
phosphorous reduction in conjunction with using a plug flow
type flow characteristic (the preferred process embodiment).
Due to the efficiency of the preferred embodiment of the
present invention and particularly of the RCAS system, an
economic and treatability improvement in the processing of
wastewater is achieved over and above traditional wastewater
treatment processes. The preferred embodiment corresponds to
a four-zone biological process and a solids capturing
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treatment zone. The biological processing zones consist of,
but are not limited to, 1) an anaerobic zone, 2) an aerobic
zone, 3) an anoxic zone and 4) an additional aerobic zone.
The solids capturing zone consists of but is not limited to
secondary clarification, tertiary clarification, filtration
and chemical addition. However, by altering the flow
characteristics by valve changes, any of the alternate
processing embodiments (described below) can be implemented
and used. The preferred processing embodiment of the present
invention is a method of processing that is zone specific and
not vessel specific.
For the preferred plug flow characteristic, the influent,
which in this embodiment is foreseen as typical municipal
wastewater, is directed through line 2 into a flow splitter
box 4 which regulates and/or splits the flow of the influent
to the treatment vessels. In this embodiment the entire flow
of influent is then directed via line 6 to vessel 8 (V # 1)
which is used as an anaerobic conditioner zone, whereby the
contents, by volume, of this zone are recirculated
substantially one time every two hours using pump 10 and the
above-mentioned RCAS. The size of the vessel 8 depends on the
volume of influent being processed.
Vessel 8 (anaerobic conditioner zone) begins the first
stage of luxury phosphorous uptake, which is biological
phosphorous (Bio-P) release. This first stage of luxury
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phosphorous uptake is accomplished by maintaining an oxygen
deficient state within the vessel. The anaerobic conditioner
zone's dissolved oxygen levels are maintained at or below 0.10
mg/L allowing a formation of volatile fatty acids (VFA's) used
by microorganisms in the release of Bio-P. While this Bio-P
release creates a temporary increase of phosphorous, it also
forces the microorganisms to metabolize greater amounts of
phosphorous during a later process. The contents of this zone
are able to be maintained with low dissolved oxygen levels by
the controlled introduction of low oxygen level mixed liquid
suspended solids (MLSS) from vessel 58 (anoxic selector zone -
V #3) from line 11 through pump 12 and through line 14 into
vessel 8 (anaerobic conditioner zone).
Aqueous total solids (TS) from vessel 8 (V # 1) flows
through line 16 into vessel 18 (V # 2) which is a dynamic
aerobic reactor # 1 zone. The vessel 18 also receives another
flow, MLSS re-cycle, which comes from vessel 20 (V # 4), which
is a dynamic aerobic reactor # 2 zone. The flow from vessel
comes from line 22 through pump 24 and finally through line
20 26. Another flow enters vessel 18 from each of the four
clarifiers (vessels 76, 80, 84, 88) - (V #5, V#6, V#7 and V#8)
in the form of return activated sludge (RAS) through RAS pumps
28, 30, 32 and 34 then through the lines 36, 38, 40 and 42,
and finally entering vessel 18 through lines 44, 46, 48 and 50
respectively. The contents, by volume, of vessel 18 are
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recirculated substantially one time every two hours, using a
re-circulation conduit aeration system (RCAS), explained
below, which is powered by pump 52. During the recirculation
procedure the contents of vessel 18 the settleable solids,
become solubilized by means of shredding as they pass through
the RCAS system of pump 52. Shredding occurs as the solids
within the aqueous solution are processed through the RCAS
system by the toroidal vortex action of the RCAS system so as
to become more easily consumed by the microorganism
population. Intense aeration is also applied through the RCAS
system during the recirculation procedure so that the level of
dissolved oxygen is substantially maintained at a
concentration of 3.5 mg/L or higher. Keeping the dissolved
oxygen concentration at these levels allows bacteria
nitrosomonas and nitrobactor, residing in the microorganism
colony, to oxidize ammonia (NH3) into nitrite (N02) and finally
into nitrate (N03) respectively. With dissolved oxygen
concentrations of this zone maintained at or above 3.5 mg/L,
suspended solids and other organic matter are decomposed and
oxidized into more stable compounds.
By using large volumes of atmospheric air delivered by
the RCAS and maintaining the dissolved oxygen at higher levels
(well above 3.5 mg/L) than that which would be maintained by
traditional aeration systems (2.0 mg/L to 3.0 mg/L), along
with long MCRT's, the microorganism colony will enter the
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biological life cycle mode known as endogenous respiration
(ER). In this ER mode, the living microorganisms begin to
metabolize some of their own cellular mass along with any new
organic matter they absorb or adsorb from their environment.
This aids in the enhancement of solids reduction while
maintaining a microorganism colony through the adjustment of
the food to microorganism ratio (F/M) to allow the rate of
death of the microorganism colony to equal the rate of growth
of the microorganism colony through the endogenous respiration
process.
Another benefit of the delivery of intense aeration
within this reactor is the enhanced consumption of large
amounts of phosphorous by the microorganisms. The amount of
phosphorous taken up by the microorganisms is greater than the
amount of phosphorous the microorganisms released in vessel 8
as described previously. The microorganisms then use this
newly acquired phosphorous for new cell wall development and
other energy needs.
Accumulation of inert solids are removed via line 5, from
vessel 18 (aerobic reactor #1) when the concentrations reach a
predetermined level. This holds true for all embodiments of
the present invention. This predetermined level could be
substantially 50°s of the concentration of total solids in
vessel 18 or a level at which the process begins to allow
nutrients to pass through to the process effluent.
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The flow exits vessel 18 via line 54, is provided to
splitter box 56 and is then provided to vessel 58 via line 60
for further processing.
The contents, by volume, of vessel 58 (anoxic selector
zone V#3) are recirculated substantially one time every two
hours by the pump 62. Vessel 58 receives elemental oxygen
attached to nitrogen molecules in the form of nitrate nitrogen
(N03) and nitrite nitrogen (N02), which was derived primarily
from the ammonia conversion process known as nitrification,
occurring within vessel 18 (aerobic reactor # 1 zone). The
amount of dissolved oxygen (DO) in vessel 58 is maintained in
the range of 0.3mg/L to 0.5mg/L. The microorganisms contained
within the wastewater of vessel 58 look for oxygen to
respirate. With little dissolved oxygen available, the
microorganisms are forced to use the elemental oxygen in the
N03 that is tied up with nitrogen. This process is commonly
called denitrification. Once the bond between the nitrogen
and oxygen is broken, the microorganisms consume the elemental
oxygen for respiration, allowing the nitrogen to be released
into the atmosphere. The microorganisms use this oxygen for
necessary respiration in order to continue consumption of
organic matter still within the wastewater.
During this anoxic condition, a natural release of
phosphorous by the microorganisms occurs, as a way to conserve
energy during the time of low dissolved oxygen availability,
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but in lesser quantities than that which occurs in vessel 8
(the anaerobic conditioner zone V #1). While this creates a
temporary increase of phosphorous, it also forces the
microorganisms to metabolize greater amounts of phosphorous in
a later process. The effluent from this process is provided
via line 64 on to vessel 20 (aerobic reactor # 2 zone-V#4) for
further treatment.
Vessel 20 is used as a dynamic aerobic reactor. The
contents, by volume, of vessel 20 are recirculated and
intensely aerated substantially one time every two hours using
the re-circulation conduit aeration system (RCAS), which is
powered by pump 66. The oxidation of both dissolved and
suspended organic matter occur in vessel 20 by maintaining a
dissolved oxygen of at least 3.0 mg/L. The bacteria
nitrosomonas and nitrobactor, residing in the microorganism
colony, will oxidize organic nitrogen into ammonia (NH3) then
into nitrite (N02) and finally into nitrate (N03) respectively.
As the aqueous solution containing the microorganism colony of
vessel 20 (dynamic aerobic reactor # 2 zone) is aerated and
the dissolved oxygen increases, the microorganisms begin
consuming phosphorous in larger quantities than is necessary
for them to sustain life. The amount of phosphorous consumed
far exceeds the amount of phosphorous the microorganisms
released into the aqueous solution while being processed
within the anaerobic conditioner zone and anoxic selector
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zones (vessel 8 and 58). This effect is what is referred to
as "luxury phosphorous uptake". Portions of the mixed liquid
suspended solids (MLSS) from vessel 20 are recycled for
further digestion to vessel 18 (dynamic aerobic reactor # 1
zone) through line 22, using pump 24 and is finally discharged
through line 26, while the effluent is discharged from vessel
20 through line 68 and into line 70 before entering a
clarification zone flow splitter box 72 (SB Clar Inf).
As the influent from line 70 enters the clarification
zone flow splitter box 72 (SB Clar Inf), the flow is
preferably split into four equal portions and sent to each of
the four clarifiers through line 74 for vessel 76
corresponding to Clarifier # 1, line 78 for vessel 80
corresponding to Clarifier # 2, line 82 for vessel 84
corresponding to Clarifier # 3 and line 86 for vessel 88
corresponding to Clarifier # 4. The flow velocity is
diminished as the flow enters each of the clarifiers, allowing
the solids to settle into the bottom portion of each of the
clarifiers. The settling solids are then dislodged from the
walls of the clarifiers by using a hydraulically operated
solids concentration inducer 90 for vessel 76 (Clarifier # 1),
hydraulically operated solids concentration inducer 92 for
vessel 80 (Clarifier # 2) hydraulically operated solids
concentration inducer 94 for vessel 84 (Clarifier # 3), and
hydraulically operated solids concentration inducer 96 for
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vessel 88 (Clarifier # 4), allowing the solids to further
thicken before being removed through each of the clarifier RAS
pumps (28, 30, 32 and 34) and RAS lines (36, 38, 40 and 42)
and sent to the vessel 18 (dynamic aerobic reactor # 1) for
further treatment. Separated liquid from the clarification
process exits vessel 76 through line 98, vessel 80 through
line 100, vessel 84 through line 102 and vessel 88 through
line 104, and join in the collection box 106 (CB Clar Eff).
This clarifier provides effluent through line 108 as the final
processed effluent.
The preferred embodiment of the present invention allows
for an improvement in operational flexibility over traditional
aerobic treatment systems.
A first alternate embodiment of the present invention is
shown in Fig. 5 wherein the unutilized lines and equipment of
the preferred apparatus embodiment of Fig. 4 are removed.
However, all the utilized lines and equipment required to
process the wastewater flow using the preferred process
embodiment are shown. The alternative embodiment depicted in
Fig. # 5 is utilized when the specific flow configuration is
contemplated for the installation and where the flexibility
offered in Fig. #4 is not required. The influent, which is
typical municipal waste water, is directed through line 2 into
vessel 8 which is used as an anaerobic conditioner zone (V#1),
whereby the contents, by volume, of the zone are recirculated
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substantially one time every two hours using pump 10. Similar
to that of the preferred embodiment, the contents of this
vessel are able to be maintained with low dissolved oxygen
levels by the controlled introduction of low oxygen level MLSS
from vessel 58 (anoxic selector zone) from line 10 through
pump 12 and fed through line 14 into vessel 8.
Aqueous total solids from vessel 8 (anaerobic conditioner
zone) flows through line 16 into vessel 18 which is a dynamic
aerobic reactor #1 zone (V#2). Vessel 18 also receives
another flow, MLSS re-cycle, which comes from vessel 20 which
is being used as dynamic aerobic reactor #2 zone. The flow
from vessel 20 comes from line 22 through pump 24 and finally
through line 26. Another flow enters vessel 18 from each of
the four clarifiers (vessels 76, 80, 84, 88 described below)
in the form of return activated sludge (RAS) through the RAS
pumps 28, 30, 32 and 34, then through the lines 36, 38, 40 and
42 respectively, and finally entering vessel 18 through lines
44, 46, 48 and 50 respectively. The contents, by volume, of
vessel 18 are re-circulated substantially one time every two
hours, using a re-circulation conduit aeration system (RCAS),
explained below, which is powered by pump 52. During the re-
circulation procedure, the contents of vessel 18, that is the
settleable solids, become solubilized by means of shredding as
it passes through the RCAS system of the zone. Shredding
occurs as the solids within the aqueous solution are processed
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through the RCAS system by the toroidal vortex action of the
RCAS system so as to become more easily consumed by the
microorganism population. Intense aeration is also applied
through the RCAS system during the re-circulation procedures
so that the level of the dissolved oxygen is substantially
maintained at a concentration of 3.5mg per liter or higher.
The flow exits vessel 18 (aerobic reactor #1 zone) via
line 110 to vessel 58 (anoxic selector zone - V#3). The
contents of vessel 58 are recirculated substantially one time
every two hours by pump 62. The operation of vessel 58 is
similar to that described in connection with Fig. 4. The
effluent from vessel 58 is provided via line 64 to vessel 20
for further treatment.
Vessel 20 is a dynamic aerobic reactor (V#4). The
contents of vessel 20 are re-circulated and intensely aerated
substantially one time every two hours using the re-
circulation conduit aeration system (RCAS), which is powered
by pump 66. The operation of vessel 20 is similar to that
described in connection with Fig. 4. As explained above,
portions of the MLSS from vessel 20 are recycled for further
processing to vessel 18 through line 22, using pump 24 and
finally discharged through line 26, while the effluent of
vessel 20 is discharged through line 68 and into line 70
before entering a clarification zone flow splitter box 72 (SB
Clar Inf).
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As the influent from line 70 enters the clarification
zone flow splitter box 72, the flow is preferably split into
four equal portions and sent to each of the four clarifiers
(V#5, V#6, V#7, V#8) through line 74 for vessel 76
corresponding to clarifier #l, line 78 for vessel 80
corresponding to clarifier #2, line 82 for vessel 84
corresponding to clarifier #3 and line 86 for vessel 88
corresponding to clarifier #4. The flow velocity is
diminished as the flow enters each of the clarifiers, allowing
the solids to settle into the bottom of each of the
clarifiers. These settling solids are then dislodged from the
vessel walls by a hydraulically operated solid concentrations
inducer 90 for vessel 76, hydraulically operated solids
concentration inducer 92 for vessel 80, hydraulically operated
solids concentration inducer 94 for vessel 84, and
hydraulically operated solids concentration inducer 96 for
vessel 88, allowing the solids to further thicken before being
removed through each of the clarifier RAS pumps (28, 30, 32
and 34) and RAS lines (36, 38, 40 and 42) and sent via lines
44, 46, 48 and 50 to the vessel 18 for further treatment.
Separated liquid from the clarification process exists vessel
76 through line 98, vessel 80 through line 100, vessel 84
through line 102 and vessel 88 through line 104, and joined in
collection box 106 (CB Clar Eff). The clarifier effluent
exists through line 108 as the final processed effluent.
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Fig. 18 is a simplified representation of the process
shown in Fig. 5 which further includes a filtration zone 89
coupled to the output of the clarifiers (line 108). The
filtration zone receives the aqueous solution (in Fig. 4 the
effulent) via line 108 for further processing. The aqueous
solution is provided to the filtration zone where solids
separate and settle from the liquid portion of the aqueous
solution. The solids which have settled and separated from
the liquid portion are provided via line 109 to the influent
line 2 for re-processing and re-treatment through the system.
The filtration zone shown in Fig. 18 can also be included in
the system shown in Fig. 4 or any of the other embodiments of
the present invention explained below.
The second alternate embodiment of the present invention
depicted in Figure 6 uses alternate process embodiment # 1 of
the present invention to provide the processing characteristic
of nitrification and de-nitrification in conjunction with a
plug flow type flow characteristic. Alternate apparatus
embodiment #2 is to be used with alternate process embodiment
# 1. Alternate processing embodiment # 1 of the present
invention is a method of processing that is zone specific and
not vessel specific.
For alternate process embodiment # 1, the influent,
represented as typical municipal wastewater, is directed
through line 120 into vessel 122 which is used as an anoxic
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selector zone (V#1), whereby the contents, by volume, of this
vessel are recirculated substantially one time every two hours
using pump 124. Other flows that enter vessel 122 come from
vessel 126 (aerobic reactor # 1 zone-V#2) via line 128 and
vessel 130 (aerobic reactor # 2 zone-V#3) via line 132 in the
form of MLSS recycle, which is used to supplement the lack of
oxygen within vessel 122. Another flow that enters vessel 122
comes from each of the four clarifiers (vessels 134, 136, 138,
140) in the form of return activated sludge (RAS) through the
RAS pumps 142, 144, 146 and 148, then finally through the
lines 150, 152, 154 and 156 respectively. Vessel 122 receives
elemental oxygen attached to nitrogen molecules in the form of
nitrate nitrogen (N03) and nitrite nitrogen (N02), which were
derived mostly from the ammonia conversion process known as
nitrification, occurring within vessels 126 and 130 (aerobic
reactor # 1 zone and aerobic reactor # 2 zone). The amount of
dissolved oxygen in vessel 122 is maintained in the range of
0.3mg/1 to 0.5mg/1. This is made possible by the recycling of
MLSS from vessel 126 (aerobic reactor # 1 zone) using pump 158
and pumping through line 128, and vessel 130 (aerobic reactor
# 2 zone) using pump 160 and pumping through line 132 into
vessel 122.
The microorganisms contained within the wastewater of
vessel 122 (anoxic selector zone) look for oxygen to
respirate. With little dissolved oxygen available, the
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microorganisms are forced to use the elemental oxygen in the
N03 that is tied up with the nitrogen gas. This process is
commonly called denitrification. Once the bond between the
nitrogen and oxygen is broken, the microorganisms consume the
elemental oxygen for respiration, allowing the nitrogen to be
released into the atmosphere.
During the consumption of oxygen, through respiration in
the denitrification process of vessel 122 (anoxic selector
zone), the microorganisms also consume portions of organic
matter in the form of total suspended solids that have been
shredded and solubilized in the recirculation process of
vessels 126, 130 (the aerobic reactor zones # 1 and # 2) so as
to become more easily consumed by the microorganism
population.
Aqueous total solids (TS) from vessel 122 (anoxic
selector zone) flows via gravity through line 162 to vessel
126 (aerobic reactor # 1 zone) for continued treatment. The
contents, by volume, of vessel 126 are recirculated
substantially one time every two hours, using the re-
circulation conduit aeration system (RCAS), which is powered
by pump 164. During the recirculation procedure the contents
of vessel 126, the settleable solids, become solubilized by
the means of shredding through the RCAS system of the vessel.
Shredding occurs as the solids within the aqueous solution are
processed through the RCAS system by the toroidal vortex
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action of the RCAS system so as to become more easily consumed
by the microorganism population. Intense aeration is also
applied through the RCAS system during recirculation so that
the level of dissolved oxygen is substantially maintained at a
concentration of 3.5 mg/L or higher. Keeping the dissolved
oxygen concentration at these levels allows the bacteria
nitrosomonas and nitrobactor, residing in the microorganism
colony, to oxidize ammonia (NH3) into nitrite (N02) and finally
into nitrate (N03) respectively. Individuals familiar in the
art know this process as nitrification. With dissolved oxygen
concentrations of this zone maintained at or above 3.5 mg/L,
suspended solids and other organic matter are decomposed and
oxidized into more stable compounds.
By using large volumes of atmospheric air delivered by
the RCAS system and maintaining the dissolved oxygen at higher
levels (well above 3.5 mg/L) than that which would be
maintained by traditional systems (2.0 mg/L to 3.0 mg/L),
along with long MCRT's, the microorganism colony will enter
the biological life cycle mode known as endogenous respiration
(ER). In this ER mode, the living microorganisms begin to
oxidize some of their own cellular mass along with any new
organic matter they absorb or adsorb from their environment.
This aids in the enhancement of solids reduction while
maintaining a microorganism colony through the adjustment of
the food to microorganism (F/M) ratio to allow the rate of
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death of the microorganisms to equal the rate of growth of the
microorganisms through the ER process.
Another benefit of the delivery of intense aeration
within this reactor is the consumption of some phosphorous by
the microorganisms.
The flow exiting vessel 126 (aerobic reactor # 1 zone)
exits through line 166 to vessel 130. Vessel 130 is used as
an aerobic reactor # 2 zone (V#3), whereby the contents, by
volume, of this vessel are recirculated and intensely aerated
substantially one time every two hours using the re-
circulation conduit aeration system (RCAS), which is powered
by pump 168. The oxidation of both dissolved and suspended
organic matter occur in this vessel by maintaining a DO level
of at least 3.0 mg/l. The bacteria nitrosomonas and
nitrobactor, residing in the microorganism colony, will
oxidize organic nitrogen into ammonia (NH3) then into nitrite
(N02) and finally into nitrate (N03) respectively in this
vessel. A portion of the nitrate rich MLSS is recycled using
pump 160 through line 132 into vessel 122 (anoxic selector
zone) for nitrogen reduction through the de-nitrification
process.
A flow also exits via gravity through line 170 into line
172 before entering the clarification zone flow split box 174
(SB Clar Inf) for the settling of solids from the liquid
portion of the wastewater.
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Note that this alternate embodiment does not include a
vessel (V#4) present in the preferred embodiment. This vessel
is not used until the flow increases substantially
necessitating the need for an additional aerobic reactor.
As the influent from line 172 enters the clarification
zone split box 174 (SB Clar Inf) the flow is split into four
equal portions and sent to each of the four clarifier vessels
(134, 136, 138, 140) through line 176 for vessel 134
(Clarifier # 1), line 178 for vessel 136 (Clarifier # 2), line
180 for vessel 138 (Clarifier # 3) and line 182 for vessel 140
(clarifier # 4). The flow velocity is diminished as the flow
enters each of the clarifiers, allowing the solids to settle
into the bottom of each of the clarifier vessels. The
settling solids are then dislodged from the cone walls by
using a hydraulically operated solids concentration inducer
184 for vessel 134, hydraulically operated solids
concentration inducer 186 for vessel 136, hydraulically
operated solids concentration inducer 188 for vessel 138, and
hydraulically operated solids concentration inducer 190 for
vessel 140, allowing the solids to further thicken before
being removed through each of the clarifier RAS pumps (142,
144, 146 and 148) and RAS lines (150, 152, 154 and 156) be and
sent to vessel 122 (anoxic reactor zone) for further
treatment. Separated liquid from the clarification process
exits vessel 134 (Clarifier # 1) through line 192, vessel 136
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(Clarifies # 2) through line 194, vessel 138 (Clarifies # 3)
through line 196 and vessel 140 (Clarifies # 4) through line
198 and join in the collection box 200 (CB Clar Eff). The
clarifies effluent exits via line 202 as the final processed
effluent.
Referring now to Fig. 7, another alternate apparatus
embodiment of the present invention is shown which employs
alternate process embodiment # 2 to provide the processing
characteristic of nitrification in conjunction with a plug
flow type flow characteristic. This alternate apparatus
embodiment is to be used with alternate process embodiment #
2. Alternate process embodiment # 2 of the present invention
is a method of processing that is zone specific and not vessel
specific.
In accordance with the present invention shown in Fig. 7,
the influent, represented as typical municipal wastewater, is
directed through line 210 into vessel 212, which is an aerobic
reactor # 1 zone. Other flows entering vessel 212 come from
four clarifiers (214, 216, 218, 220) in the form of return
activated sludge (RAS) through RAS pumps (222, 224, 226 and
228) and are delivered to vessel 212 through lines 230, 232,
234 and 236 respectively.
The contents, by volume, of vessel 212 (aerobic reactor
#1 zone) are recirculated substantially one time every two
hours, using the re-circulation conduit aeration system
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(RCAS), which is powered by pump 238. During the
recirculation procedure the contents of vessel 212, the
settleable solids, become solubilized by means of shredding
through the RCAS system. Shredding occurs as the solids
within the aqueous solution are processed through the RCAS
system by the toroidal vortex action of the RCAS system so as
to become more easily consumed by the microorganism
population. Intense aeration is also applied through the RCAS
system during recirculation so that the level of dissolved
oxygen is substantially maintained at a concentration of 3.5
mg/L or above. Keeping the dissolved oxygen concentration at
these levels allows the bacteria nitrosomonas and nitrobactor,
residing in the microorganism colony, to oxidize ammonia (NH3)
into nitrite (N02) and finally into nitrate (N03) respectively.
Individuals familiar in the art know this process as
nitrification. With dissolved oxygen concentrations of this
zone maintained at or above 3.5 mg/L, suspended solids and
other organic matter are decomposed and oxidized into more
stable compounds.
By using large volumes of atmospheric air delivered by
the RCAS system and maintaining the dissolved oxygen at higher
levels (well above 3.5 mg/L) than that which would be
maintained by traditional systems (2.0 mg/L to 3.0 mg/L),
along with long MCRT's, the microorganism colony will enter
the biological life cycle mode known as Endogenous Respiration
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(ER). In this ER mode, the living microorganisms begin to
oxidize some of their own cellular mass along with any new
organic matter they absorb or adsorb from their environment.
This aids in the enhancement of solids reduction while
maintaining a microorganism colony through the adjustment of
the food to microorganism ratio (F/M) to allow the rate of
death of the microorganisms to equal the rate of growth of the
microorganisms through the ER process.
Another benefit of the delivery of intense aeration
within this reactor is the consumption of some phosphorous by
the microorganisms.
The flow exits vessel 212 (aerobic reactor #1 zone)
through line 239 into vessel 240 (aerobic reactor #2 zone-V#2)
for further aerobic treatment. The contents, by volume, of
vessel 240 are recirculated substantially one time every two
hours, using the re-circulation conduit aeration system
(RCAS), which is powered by pump 242. During recirculation of
the contents of vessel 240, additional intense aeration is
applied and the level of dissolved oxygen is substantially
maintained at a concentration of 3.0 mg/L or above. Keeping
the dissolved oxygen concentration at these levels allows
microorganisms the ability to convert organic matter,
including but not limited to total BOD, and also organic
nitrogen first into ammonia, then nitrite and finally into
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nitrate. This process reduces the concentrations of total
nitrogen into less harmful compounds.
The flow exits vessel 240, preferably via gravity,
through line 243 into line 244 before entering clarification
zone flow split box 246 (SB Clar Inf) for the settling of
solids from the liquid portion of the wastewater.
Note that additional aerobic reactor vessels described in
the previous embodiments are not used in this embodiment until
the flow increases substantially necessitating the need for
additional aerobic reactors.
As the influent from line 244 enters the clarification
zone splitter box 246 (SB Clar Inf), the flow is preferably
split into four equal portions and sent to each of the four
clarifiers (vessels 214, 216, 218, 220) through line 248 for
vessel 214 (Clarifier # 1), line 250 for vessel 216 (Clarifier
# 2), line 252 for vessel 218 (Clarifier # 3) and line 254 for
vessel 220 (Clarifier # 4). The flow velocity is diminished
as the flow enters each of the clarifiers, allowing the solids
to settle into the bottom of each of the clarifiers. The
settling solids are then dislodged from the walls by using a
hydraulically operated solids concentration inducer 256 for
vessel 214, hydraulically operated solids concentration
inducer 258 for vessel 216, hydraulically operated solids
concentration inducer 260 for vessel 218 and hydraulically
operated solids concentration inducer 262 for vessel 220,
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allowing the solids to further thicken before being removed
through each of the clarifier RAS pumps (222, 224, 226 and
228) and RAS lines (230, 232, 234 and 236) and sent to vessel
212 (aerobic reactor # 1 zone) for further treatment.
Separated liquid from the clarification process, exits vessel
214 through line 264, vessel 216 through line 266, vessel 218
through line 268 and vessel 220 through line 270 and joins in
the collection box 272 (CB Clar Eff). The clarifier effluent
exits through line 274 as the final processed effluent.
Referring now to Fig. 8, another alternate embodiment of
the present invention is shown which utilizes the alternate
processing embodiment # 3 of the present invention to provide
the processing characteristics of nitrification,
de-nitrification and phosphorous reduction in conjunction with
using a step feed flow type flow characteristic, giving
improved operational flexibility. The use of this alternate
embodiment in conjunction with alternate processing embodiment
# 3 would be preferable when there is a change in feed
preferences or the parameters change and the effluent quality
needs to be improved. This would also hold true for influent
nutrient load variations while the influent flow
characteristics remain the same. Alternate processing
embodiment # 3 of the present invention is a method of
processing that is zone specific and not vessel specific.
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For alternate process embodiment # 3, the influent is a
high strength waste, which could contain a high concentration
of NH3, with a high TSS concentration and a high total BOD
concentration, while requiring nitrification, de-nitrification
and phosphorous reduction as might need to be demonstrated by
the influent concentrations of an industrial strength waste
stream.
In the alternate embodiment shown in Fig. 8, influent
containing suspended solids and biodegradable organic
substances passes through line 280 to splitter box 282 (SB PLT
Inf), where it is diverted, sending 600 of the total influent
flow into vessel 284 (anaerobic conditioner zone-V #1) via
line 286, 300 of the total influent flow through line 288 into
the vessel 290 (aerobic reactor #1 zone-V #2) and 5% being
diverted through line 292 to vessel 294 (anoxic selector zone-
V #3) while the other 5o is diverted thorough line 296 to
vessel 298 (aerobic reactor # 2 zone-V #4).
Vessel 284 receives 600 of the plant influent flow and a
flow from vessel 294 through line 300 using pump 302 and line
304. The contents, by volume, of vessel 284 are recirculated
substantially one time every two hours using pump 306.
Vessel 284 (anaerobic conditioner zone) begins the first
stage of luxury phosphorous uptake, which is biological
phosphorous (Bio-P) release. Luxury phosphorous uptake is
accomplished by maintaining an oxygen deficient state within
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vessel 284. Dissolved oxygen levels are maintained at or
below 0.10 mg/L causing Bio-P release by the microorganisms.
While this Bio-P release creates a temporary increase of
phosphorous, it also forces the microorganisms to metabolize
greater amounts of phosphorous during a later process. The
contents of this zone are able to maintain low dissolved
oxygen levels by the controlled introduction low oxygen level
MLSS from vessel 294 (anoxic selector zone) from line 300
through pump 302 and through line 304 into vessel 284. The
flow then continues on through line 308 to vessel 290 (aerobic
reactor # 1 zone) for treatment.
As mentioned above, vessel 290 receives 300 of the plant
influent flow through line 288 and is used as aerobic reactor
# 1 zone. Another flow that enters this vessel comes from
vessel 298 through line 310 using pump 312 then through line
314 discharging into vessel 290. The flow from vessel 298
(aerobic reactor #2 zone) is in the form of MLSS recycle.
Still another flow entering vessel 290 comes from each of the
four clarifier vessels (316, 318, 320, 322) in the form of
return activated sludge (RAS) through the RAS pumps 324, 326,
328 and 330, and then finally through the lines 332, 334, 336
and 338 respectively. The contents, by volume, of vessel 290
are recirculated substantially one time every two hours, using
the re-circulation conduit aeration system (RCAS), which is
powered by pump 340. During the recirculation procedure the
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contents of vessel 284, the settleable solids, become
solubilized by means of shredding as they pass through the
RCAS system of the vessel. The shredding occurs as the solids
within the aqueous solution are processed through the RCAS
system by the toroidal vortex action of the RCAS system so as
to become more easily consumed by the microorganism
population. Intense aeration is also applied during the
recirculation procedure so that the level of dissolved oxygen
is substantially maintained at a concentration of 3.5 mg/L or
above. Keeping the dissolved oxygen concentration at these
levels allows the bacteria nitrosomonas and nitrobactor,
residing in the microorganism colony, to oxidize ammonia (NH3)
into nitrite (N02) and finally into nitrate (N03) respectively.
With dissolved oxygen concentrations in this zone at or above
3.5 mg/L, suspended solids and other organic matter are
decomposed and oxidized into more stable compounds. By using
large volumes of atmospheric air delivered by the RCAS system
and maintaining the dissolved oxygen at higher levels (above
3.0 mg/L) than that which would be maintained by traditional
aeration systems, along with long MCRT's, the microorganism
colony will enter the biological life cycle mode known as
endogenous respiration (ER). In this ER mode, the living
microorganisms begin to oxidize some of their own cellular
mass along with any new organic matter they absorb or adsorb
from their environment. This aids in the enhancement of
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solids reduction while maintaining a microorganism colony
through the adjustment of the food to microorganism (F/M)
ratio to allow the rate of death of the microorganism colony
to equal the rate of growth of the microorganism colony
through the ER process.
Another benefit of the delivery of intense aeration
within this reactor is the enhanced consumption of large
amounts of phosphorous by the microorganisms. The amount of
phosphorous taken up by the microorganisms is in greater
amounts than the amount of phosphorous the microorganisms
released in vessel 284 (anaerobic conditioner zone) as
described above. The microorganisms then use this newly
acquired phosphorous for new cell wall development and other
energy needs.
The flow then exits vessel 290 (aerobic reactor # 1 zone)
through line 342 into vessel 294 (anoxic selector zone) for
further processing. In addition to the flow through line 342
from vessel 290, vessel 294 also receives an additional flow
of 5o of the plant influent through line 292. The contents,
by volume, of this vessel are recirculated substantially one
time every two hours by pump 344. This anoxic selector zone
receives elemental oxygen attached to nitrogen molecules in
the form of nitrate nitrogen (N03) and nitrite nitrogen (N02),
which were derived mostly from the ammonia conversion process
known as nitrification occurring within vessel 290 (the
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aerobic reactor # 1 zone). The amount of dissolved oxygen
(DO) in vessel 294 is maintained in the range of 0.3mg/1 to
0.5mg/l. The microorganisms contained within the wastewater
of vessel 294 look for oxygen to respirate. With little DO
available, the microorganisms are forced to use the elemental
oxygen in the N03 that is tied up with nitrogen. This process
is commonly called denitrification. Once the bond between the
nitrogen and oxygen is broken, the microorganisms consume the
elemental oxygen for respiration, allowing the nitrogen to be
released into the atmosphere. The microorganisms use this
oxygen for the necessary respiration in order to continue
consumption of organic matter still within the wastewater.
During this anoxic condition, a natural release of
phosphorous by the microorganisms occurs, as a way to conserve
energy during the time of low dissolved oxygen availability,
but in lesser quantities than occur in vessel 284 (anaerobic
conditioner zone). While this creates a temporary, but
slight, increase of phosphorous, it also forces the
microorganisms to metabolize greater amounts of phosphorous in
a later process. The effluent from this process would
continue through line 346 on to vessel 298 (aerobic reactor #2
zone) for further treatment.
In addition to the flow which enters the vessel 298
(aerobic reactor #2 zone) through line 346, a flow of 50 of
the plant influent is provided into vessel 298 through line
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296. The contents, by volume, of this zone are recirculated
and intensely aerated substantially one time every two hours
using the re-circulation conduit aeration system (RCAS), which
is powered by pump 348. The oxidation of both dissolved and
suspended organic matter occur in this vessel by maintaining a
dissolved oxygen of at least 3.5 mg/1. The bacteria
nitrosomonas and nitrobactor, residing in the microorganism
colony, will oxidize organic nitrogen into ammonia (NH3) then
into nitrite (N02) and finally into nitrate (N03) respectively
in this vessel. As the aqueous solution containing the
microorganism colony of vessel 298 is aerated and the
dissolved oxygen increases, the microorganisms will also begin
to consume phosphorous in larger quantities than is necessary
for them to sustain life. The amount of phosphorous consumed
far exceeds the amount of phosphorous the microorganisms
released into the aqueous solution while being processed
within vessels 284 and 294 (anaerobic conditioner zone and
anoxic selector zone). This is what is referred to in the
industry as "luxury phosphorous uptake". Portions of the MLSS
from vessel 298 are recycled to vessel 290 (aerobic reactor #
1 zone), through line 310, using pump 312 and finally
discharging through line 314, while the effluent continues on
through line 350 and into line 352 before entering the
clarification zone flow splitter box 354 (SB Clar Inf).
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As the influent from line 352 enters the clarification
zones splitter box 354, the flow is preferably split into four
equal portions and sent to each of the four clarifiers (316,
318, 320, 322) through line 356 for vessel 316 (Clarifies #
1), line 358 for vessel 318 (Clarifies # 2), line 360 for
vessel 320 (Clarifies # 3) and line 362 for vessel 322
(Clarifies # 4). The flow velocity is diminished as the flow
enters each of the clarifiers, allowing the solids to settle
into the bottom of each of the clarifiers. The settling
solids are then dislodged from the walls of each clarifies
vessel by using a hydraulically operated solids concentration
induces 364 for vessel 316 (Clarifies # 1), hydraulically
operated solids concentration induces 366 for vessel 318
(Clarifies # 2), hydraulically operated solids concentration
induces 368 for vessel 320, (Clarifies # 3), hydraulically
operated solids concentration induces 370 for vessel 322
(Clarifies # 4), allowing the solids to further thicken before
being removed through each of the clarifies RAS pumps (324,
326, 328 and 330) and RAS lines (332, 334, 336 and 338) and
sent to vessel 290 (aerobic reactor # 1 zone) for further
treatment. Separated liquid from the clarification process,
exits vessel 316 (Clarifies # 1) through line 372, vessel 318
(Clarifies # 2) through line 374, vessel 320 (Clarifies # 3)
through line 376 and vessel 322 (Clarifies # 4) through line
378, and are combined in collection box 380 (CB Clar Eff).
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The clarifier effluent exits through line 382 as the final
processed effluent.
Referring now to Fig. 9, another alternate embodiment of
the present invention is shown which utilizes an alternate
S process embodiment #4 to provide the processing
characteristics of nitrification and de-nitrification in
conjunction with using a step feed flow type flow
characteristic. Alternate processing embodiment #4 of the
present invention is a method of processing that is zone
specific and not vessel specific.
For alternate process embodiment # 4, the influent is a
high strength waste, which could contain a high NH3
concentration, with a high TSS concentration and a high total
BOD concentration, while requiring nitrification and
de-nitrification for a total nitrogen reduction as might need
to be demonstrated by the influent concentrations of an
industrial strength waste stream.
Referring now to Fig. 9, an alternate embodiment of the
present invention is shown wherein influent containing
suspended solids and biodegradable organic substances, is
passed through line 390 to splitter box 392 (SB PLT Inf),
where it is diverted, sending 750 of the total influent flow
through line 394 into vessel 396 (anoxic selector zone - V #
1), 15s of the total influent flow is diverted by splitter box
392 through line 398 into the vessel 400 (aerobic reactor #1
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zone V # 2) and the remaining 100 of the total influent flow
is diverted by splitter box 392 through line 402 to vessel 404
(aerobic reactor #2 zone V # 3).
Vessel 396 (V # 1) is used as an anoxic selector zone
$ receiving 750 of the influent flow through line 394. An
additional flow in the form of MLSS Recycle is received from
vessel 404 (V # 3) through line 406, pump 408 and line 410.
Dissolved oxygen in vessel 396 is kept at a level below 0.5
mg/L for denitrification. Vessel 396 is rich in aerobic
microorganisms and combined oxygen in the form of nitrate
received from vessel 404. With the levels of dissolved oxygen
in the 0.5 mg/L range, the aerobic microorganisms are forced
to use nitrate for respiration thus being used for the purpose
of denitrification of the wastewater prior to continuing on to
further processing.
The influent flow received through line 390 is rich in
nutrients, while the flow received through line 410 from
vessel 404 is rich in nitrate and microorganisms. Therefore,
in step feeding a portion of the influent flow into this
vessel, the organic load entering the plant can be increased
without any alterations to the current design of the preferred
apparatus embodiment of the present invention. The contents,
by volume of vessel 396 are recirculated one time every two
hours by pump 412. Flow exits vessel 396 through line 414
into vessel 400 for further treatment.
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Vessel 400 (V # 2) is used as an aerobic reactor # 1
zone, receiving 150 of the total influent flow through line
398 and flow from vessel 396 through line 414. Additional
flow comes from each of the clarifiers (416, 418, 420, 422)
in the form of return activated sludge (RAS). The contents,
by volume, of this vessel are recirculated substantially one
time every two hours, using the re-circulation conduit
aeration system (RCAS), which is powered by pump "424".
During the recirculation procedure the contents of vessel 400,
the settleable solids, become solubilized by means of
shredding as they pass through the RCAS system of the zone.
The shredding occurs as the solids within the aqueous solution
are processed through the RCAS system by the toroidal vortex
action of the RCAS system so as to become more easily consumed
by the microorganism population. Intense aeration is also
applied during the recirculation procedure so that the level
of dissolved oxygen is substantially maintained at a
concentration of 3.5 mg/L or above. Keeping the dissolved
oxygen concentration at these levels allows the bacteria
nitrosomonas and nitrobactor, residing in the microorganism
colony, to oxidize ammonia (NH3) into nitrite (N02) and finally
into nitrate (N03) respectively. Individuals familiar in the
art know this process as nitrification.
With dissolved oxygen concentrations in this zone at or
above 3.5 mg/L, suspended solids and other organic matter are
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decomposed and oxidized into more stable compounds. This
initial decomposition of organic matter, which is the breaking
down of organic matter from complex forms to more simple
forms, mainly through the digestion action of aerobic
bacteria.
By using large volumes of atmospheric air delivered by
the RCAS system and maintaining the dissolved oxygen at higher
levels (above 3.5 mg/L) than that which would be maintained by
traditional aeration systems, along with long MCRT's, the
microorganism colony will enter the biological life cycle mode
known as endogenous respiration (ER). In this ER mode, the
living microorganisms begin to oxidize some of their own
cellular mass along with any new organic matter they absorb or
adsorb from their environment. This aids in the enhancement
of solids reduction while maintaining a microorganism colony
through the adjustment of the food to microorganism (F/M)
ratio to allow the rate of death of the microorganism colony
to equal the rate of growth of the microorganism colony
through the ER process. The flow exits vessel 400 (aerobic
reactor # 1 zone) through line 426 to vessel 404 (aerobic
reactor #2 zone V # 3). An additional l00 of the influent
flow enters vessel 404 (V # 3) from the splitter box 392 (SB
PLT Inf) through line 402.
The contents, by volume, of vessel 404 is recirculated
and intensely aerated substantially one time every two hours
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using the re-circulation conduit aeration system (RCAS), which
is powered by pump 428. During the recirculation of the
contents of vessel 404, the settleable solids become further
solubilized by the means of shredding through the
recirculation pumping of the zone so as to become further
consumed by the microorganism population. Intense aeration is
also applied during recirculation so that the level of
dissolved oxygen is substantially maintained at a
concentration of 3.0 mg/L or above. The bacteria nitrosomonas
and nitrobactor, residing in the microorganism colony, will
oxidize organic nitrogen into ammonia (NH3) then into nitrite
(N02) and finally into Nitrate (N03) respectively in this zone.
Keeping the dissolved oxygen concentration at levels
above 3.5 mg/L allows the microorganism colony the ability to
convert organic matter, including but not limited to
additional total BOD, along with additional organic nitrogen
first into ammonia, then nitrite and finally into nitrate and
other less harmful compounds. This process reduces the
concentrations of total nitrogen released into the aquatic
environment through the denitrification process. The
dissolved oxygen in vessel 404 (aerobic reactor # 2 zone)
maintains a concentration of at least 3.5 mg/L to ensure
complete decomposition and oxidation of the organic nutrients
within the waste stream.
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Portions of the contents of vessel 404 is recycled to
vessel 396 (anoxic selector zone) in the form of MLSS recycle
in line 406 using pump 408 and finally through in line 410.
The MLSS, which is rich in aerobic microorganisms and combined
oxygen, is denitrified in vessel 396 prior to returning to the
vessels 400, 404 for continued treatment of remaining
nutrients.
The Effluent from this processes exits vessel 404 through
line 430 into line 432 for the clarification process. As the
influent from line 432 enters the clarification zone splitter
box 434 (SB Clar Inf) the flow is preferably split into four
equal portions and sent to each of the four clarifiers (416,
418, 420, 422) through line 436 for vessel 416 (clarifier #
1), line 438 for vessel 418 (clarifier # 2), line 440 for
vessel 420 (clarifier # 3) and line 442 for vessel 422
(clarifier # 4). The flow velocity is diminished as the flow
enters each of the clarifiers, allowing the solids to settle
into the bottom of each of the clarifiers. The settling
solids are then dislodged from off of the cone walls by using
a hydraulically operated solids concentration inducer 444 for
vessel 416, hydraulically operated solids concentration
inducer 446. for vessel 418, hydraulically operated solids
concentration inducer 448 for vessel 420, hydraulically
operated solids concentration inducer 450 for vessel 422
allowing the solids to further thicken before being removed
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through each of the clarifiers RAS pumps (452, 454, 456, 458)
and RAS lines (460, 462, 464, 466) and sent to vessel 400
(aerobic reactor # 1 zone) for further treatment. Separated
liquid from the clarification process, exits vessel 416
through line 468, vessel 418 through line 470, vessel 420
through line 472 and vessel 422 through line 474 and join in
the collection box 476 (CB Clar Eff). This clarifier effluent
exits through line 478 as the final processed effluent.
The alternate embodiment as depicted in Fig. 10 shows the
unutilized lines, vessels and equipment of the Preferred
Apparatus Embodiment removed. However, all the utilized
lines, vessels and equipment required to process the
wastewater flow using alternate process embodiment # 4 are
shown.
Referring now to Fig. 10, an alternate apparatus
embodiment of the present invention is shown which utilizes
the alternate process embodiment # 5 of the present invention
to provide the processing characteristics of nitrification in
conjunction with using a step feed flow type flow
characteristic. Alternate processing embodiment # 5 of the
present invention is a method of processing that is zone
specific and not vessel specific.
For alternate process embodiment # 5, the influent is
represented as a high strength waste which could contain a
high NH3 concentration, with a high TSS concentration and a
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high total BOD concentration, while requiring nitrification as
might need to be demonstrated by the influent concentrations
of an industrial strength waste stream.
In the present alternate embodiment of Fig. 10 the
influent containing suspended solids and biodegradable organic
substances passes through line 500 to splitter box 502 (S8 PLT
Inf), where it is diverted. 50% of the total influent flow is
provided into the vessel 504 (aerobic reactor # 1 zone-V#1)
via line 506, 30% of the total influent flow is diverted
through the splitter box 502 (SB PLT Inf) through line 508
into the vessel 510 (aerobic reactor # 2 zone-V#2) and the
remaining 200 of the influent is diverted by the splitter box
502 (SB PLT Inf) through line 512 to vessel 532 (aerobic
reactor # 3 zone-V#3).
As stated above, the vessel 504 is used as aerobic
reactor # 1 zone, receiving 500 of the total influent flow.
Additional flows come from each of the clarifiers (516, 518,
520, 522) in the form of return activated sludge (RAS). The
contents, by volume, of vessel 504 are recirculated
substantially one time every two hours, using the re-
circulation conduit aeration system (RCAS), which is powered
by pump 524. During the recirculation procedure the contents
of the vessel 504, the settleable solids, become solubilized
by means of shredding as they pass through the RCAS system of
the vessel. The shredding occurs as the solids within the
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aqueous solution are processed through the RCAS system by the
toroidal vortex action of the RCAS system so as to become more
easily consumed by the microorganism population. Intense
aeration is also applied during the recirculation procedure so
that the level of dissolved oxygen is substantially maintained
at a concentration of 3.5 mg/L or above. Keeping the
dissolved oxygen concentration at these levels allows the
bacteria nitrosomonas and nitrobactor, residing in the
microorganism colony, to oxidize ammonia (NH3) into nitrite
(N02) and finally into nitrate (N03) respectively. Individuals
familiar in the art know this process as nitrification.
With dissolved oxygen concentration levels in this zone
at or above 3.5 mg/L, suspended solids and other organic
matter, including but not limited to carbonaceous BOD, are
decomposed and oxidized into more stable compounds. This
initial decomposition of organic matter, which is the breaking
down of organic matter from complex forms to simpler forms,
occurs mainly through the digestion action of aerobic
bacteria.
By using large volumes of atmospheric air delivered by
the RCAS system and maintaining the dissolved oxygen at higher
levels (above 3.5 mg/L) than that which would be maintained by
traditional aeration systems, along with long MCRT's, the
microorganism colony will enter the biological life cycle mode
known as Endogenous Respiration (ER). In this ER mode, the
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living microorganisms begin to oxidize some of their own
cellular mass along with any new organic matter they absorb or
adsorb from their environment. This aids in the enhancement
of solids reduction while maintaining a colony through
adjusting the food to microorganism ratio to allow the rate of
death of the microorganisms to equal the rate of growth of the
microorganisms through ER.
Another benefit of the intense aeration within this
vessel is the consumption of some phosphorous by the
microorganisms.
The flow exits vessel 504 (the aerobic reactor # 1 zone)
through line 526 and is provided into vessel 510 for further
aerobic treatment.
The flow enters vessel 510 from vessel 504 along with 300
of the plant influent flow which is provided by line 508.
Vessel 510 is used as an aerobic reactor # 2 zone. The
contents, by volume, of this vessel are recirculated
substantially one time every two hours, using the re-
circulation conduit aeration system (RCAS), which is powered
by pump 528. During the recirculation procedure the contents
of vessel 510 (the aerobic reactor # 2 zone), the settleable
solids, become solubilized by means of shredding as they pass
through the RCAS. Another benefit of the RCAS system of
vessel 510 (aerobic reactor # 2 zone) is additional intense
aeration being applied and the level of dissolved oxygen is
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substantially maintained at a concentration of 3.5 mg/L or
above. Keeping the dissolved oxygen concentration at these
levels gives the microorganism colony the ability to convert
organic matter, including but not limited to total BOD.
Organic nitrogen is also converted, first into ammonia, then
nitrite and finally into nitrate. This process reduces the
concentrations of total nitrogen and total BOD into less
harmful compounds. Once again, microorganisms consume
additional amounts of phosphorous reducing the phosphorous
concentrations in the system.
The flow exits vessel 510 (aerobic reactor # 2 zone)
through line 530 and is provided into vessel 532 (aerobic
reactor #3 zone). Flow also enters vessel 532 from the
splitter box 502 (100 of the plant influent flow via line
512). The contents, by volume, of vessel 532 are recirculated
substantially one time every two hours, using the re-
circulation conduit aeration system (RCAS), which is powered
by pump 534. During the recirculation procedure the contents
of vessel 532, the settleable solids, become solubilized by
means of shredding as they pass through the RCAS system.
Another benefit of the RCAS system of vessel 532 is additional
intense aeration being applied and the level of dissolved
oxygen is substantially maintained at a concentration of 3.5
mg/L or above. Keeping the dissolved oxygen concentration at
these levels gives the microorganism colony the ability to
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convert organic matter, including but not limited to total
BOD. This process reduces the concentrations total BOD into
less harmful compounds. Once again, unavoidably, the
microorganisms consume additional amounts of phosphorous.
The flow exits vessel 532 via gravity through line 536
into line 538 before entering the clarification zone flow
splitter box 540 (SB Clar Inf.) for the settling of the solids
portion from the liquid portion of the wastewater.
As the influent from line 538 enters the clarification
zone splitter box 540 (SB Clar Inf) the flow is preferably
split into four equal portions and sent to each of the four
clarifiers (516, 518, 520, 522) through line 542 for vessel
516 (Clarifier # 1), line 544 for vessel 518 (Clarifier # 2),
line 546 for vessel 520 (Clarifier # 3) and line 548 for
vessel 522 (Clarifier # 4). The flow velocity is diminished
as the flow enters each of the clarifier vessels, allowing the
solids to settle into the bottom of each of the clarifier
vessels. The settling solids are then dislodged from the cone
walls by hydraulically operated solids concentration inducer
550 for vessel 516 (Clarifier # 1), hydraulically operated
solids concentration inducer 552 for vessel 518 (Clarifier #
2), hydraulically operated solids concentration inducer 554
for vessel 520 (Clarifier # 3) and hydraulically operated
solids concentration inducer 556 for vessel 522 (Clarifier #
4), allowing the solids to further thicken before being
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removed through each of the clarifier RAS pumps (558, 560,
562, 564) and RAS lines (566, 568, 570, 572) and sent to
vessel 504 (aerobic reactor # 1 zone) for further treatment.
Separated liquid from the clarification process, exits vessel
516 through line 574, vessel 518 through line 576, vessel 520
through line 578 and vessel 522 through line 580 and join in
the collection box 582 (CB Clar Eff). The clarifier effluent
exits through line 584 as the final processed effluent.
Re-Circulation Aeration System (RCAS)
Referring now to Fig. 15, one of the main components of
the enhanced solids reduction wastewater treatment process of
the present invention is shown. The RCAS is an efficient
means of shredding, mixing, agitating, circulating, aerating,
homogenizating and saturating the wastewater, with each of the
aforementioned employed, as the demand requires. The RCAS is
a type of conduit conveyance system that takes the contents
of a vessel through a mechanical pump creating a high velocity
flow of the vessel contents through a differential injector,
which is preferably located on the exterior portion of each
vessel for ease of maintenance. The air passing through the
differential injector is injected into the wastewater
treatment flow which is then returned back to the vessel. As
the contents of the vessel pass through the RCAS system, a
shredding of organic solids occurs such that the organic
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solids become solubilized and homogenized for easier digestion
by microorganisms. Another benefit of the RCAS system is the
destruction of pathogenic microorganisms by the toroidal
vortex action at the discharge of the device (in line
injector/mixer/aerator) creating agitation.
The RCAS includes a suction side conduit 600 coupled to
the suction side of a pump 602, a discharge side conduit 604
that contains within it an in-line injector/mixer/aerator 606
such as the one described in USP 5,893,641, (the entire
disclosure of which is incorporated herein by reference), an
air/oxygen supply source conduit 608 and a delivery conduit
610. The pump 602 evacuates the wastewater from the vessel 612
containing aqueous solution delivering it through the conduit
600 to the aerator 606 for mixing, aeration and agitation. The
wastewater is then returned to vessel 612 via conduit 610
where the excess atmospheric air that is entrapped within the
bubbles traveling along with the wastewater within conduit 610
are released causing a secondary aeration, agitation and
mixing effect to the wastewater contained within vessel 612.
During the wastewater's travel, it is passed through an
aerator 606, as shown in FIG. 15, where atmospheric air is
drawn in by vacuum (venturi effect). The wastewater and
atmospheric air are mixed at the discharge of the in-line
aerator 608 and while they are encapsulated within the conduit
610, saturating the wastewater with oxygen. The aerator 606
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may be the aerator as shown in USP 5,893,641 or any other
aerator device of similar performance, such as any of the
aerators shown in pending PCT Application Serial No.
PCT/US01/11936, or U.S. Application Serial No. 09/547,447, the
entire disclosures of which are incorporated herein by
reference.
The oxygen saturated mixed wastewater travels through the
conduit 610, and then is discharged back into the vessel 612.
Carried along with the saturated wastewater within the conduit
610 are excess bubbles of atmospheric air that were injected
into the wastewater stream, over and above the quantity
required for the complete saturation of the wastewater
traveling within the conduit 610. When the excess air is
discharged from the conduit 610 into the vessel, along with
the saturated wastewater, the excess air becomes a source of
additional air delivered to the contents of vessel 612, and
thereby furthering the aeration process of the entire contents
of the vessel by providing additional oxygen supply to be
absorbed by the not as yet re-circulated contents of the
vessel.
An alternate flow of some or all of the wastewater
through conduit 614 would enable additional controls to be
available for diminishing the aeration while continuing with
the mixing capabilities of the system.
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Under certain conditions, induced pressures can be
produced by adding resistance to the delivery conduits with
restrictions or friction losses (i.e. conduit size reductions)
fittings, valves, nozzles, etc.
For certain conditions regarding conduit 610, such as in
the case of specific conduit size requirements, specific
conduit length requirements, where the installation of the
RCAS system is limited to confined parameters that do not meet
the design requirements for the aeration or mixing process,
induced pressures can be produced within the conduit 610 that
would provide compensation to the environment within conduit
610. These compensations in the design of conduit 610 would
equal characteristics of a conduit of different diameter,
length or desired pressure contained within such conduit so as
to deliver the specific aeration criteria desired. The
compensations that would be contemplated are represented by
the addition of valves, fittings, in-line mixers, a reduction
or increase of conduit diameter, or the inclusion of a
restriction, such as an orifice, in the conduit 610.
Through the re-circulation events, oxygen transfer
abilities and creation of micro-bubbles by the RCAS system, a
reduction in power consumption is achieved over traditional
aeration systems, which use blowers and compressors. These
efficiencies of the RCAS allow the present invention to use a
smaller footprint for total plant design.
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Aeration of an aqueous solution is important to aerobic
digestion of biological nutrients. The smaller the bubble,
the greater the aerobic digestion activity of the bacteria and
other microorganisms, due to the respiration of easily
accessible dissolved oxygen. With these two facts in mind,
the best possible forms of bubbles to deliver are micro-
bubbles. These are provided by the RCAS System of the present
invention.
Oxidative biological and chemical processes in aqueous
environments are limited by the low solubility of oxygen in
water. This physical limitation as defined by Henry's Law
states that when the temperature is kept constant, the amount
of a gas that dissolves into a liquid is proportional to the
pressure exerted by the gas on the liquid. In the use of the
RCAS system, the pressure of the gas and liquid are increased
beyond atmospheric pressure so as to increase the amount of
gaseous oxygen able to be dissolved in wastewater.
The solubility of oxygen in pure water is only about 10
parts per million (ppm) at ambient temperatures and at one
atmosphere pressure.
For most aerobic bioprocesses, dissolved oxygen is
quickly consumed so that replenishing it becomes the factor
that limits the rate of the process. Therefore, a most
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critical component of a bioprocess design is the means for the
mass transfer of oxygen into the liquid phase of the process.
For an actively respiring culture of bacteria, oxygen in the
liquid medium must be replaced as needed at a sufficient rate
to keep up with the oxygen demand of the bacteria. With the
RCAS system used in the present invention, the dissolved
oxygen is replenished at a rate that exceeds the oxygen demand
of the bacteria.
Water is typically aerated by providing contact surfaces
between the gaseous and liquid phases. This can be done
either by introducing a source of oxygen into a bulk liquid
phase or by flowing dispersed water through a bulk gaseous
(air) phases. Regardless of whether the gaseous or liquid
phases dominate the oxygenation process, the mass transfer of
oxygen, or other gas, is accomplished by introducing gas
bubbles into the liquid phase. The efficiency of gas-liquid
mass transfer depends to a large extent on the characteristics
of the bubbles. Bubble behavior strongly affects the
following mass-transfer parameters of:
(a) Transfer of oxygen from the interior of the
bubble to the gas-liquid interface;
(b) Movement of oxygen across the gas-liquid
interface; and
(c) Diffusion of oxygen through the relatively
stagnant liquid film surrounding the bubble.
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It is generally agreed that a most important property of
air bubbles in a bioprocess is their size. For a given volume
of gas, more interfacial area between the gas phase and liquid
phase is provided if the gas is dispersed into many small
bubbles rather than a few large ones. Small bubbles, 1-3 mm,
have been shown to have the following beneficial properties
not shared by larger bubbles.
Small gas bubbles rise more slowly than large bubbles,
allowing more time for a gas to dissolve in the aqueous phase.
This property is referred to as gas hold-up, concentrations of
oxygen in water can be more than doubled beyond Henry's Law
solubility limits. For example, after a saturation limit of 10
ppm oxygen is attained, at least another 10 ppm oxygen within
small bubbles would be available to replenish the oxygen.
Once a bubble has been formed, the major barrier for
oxygen transfer to the liquid phase is the liquid film
surrounding the bubble. Biochemical engineering studies have
concluded that transport through this film becomes the rate-
limiting step in the complete process, and controls the
overall mass-transfer rate. However, as bubbles become
smaller, this liquid film thickness decreases so that the
transfer of gas into the bulk liquid phase is no longer
impeded.
When air is introduced by means of a vacuum, as with the
RCAS system, at a velocity and volume equal to the flow of an
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aqueous solution through a pump, the formation of micro
bubbles occurs. These micro bubbles have the size necessary
to remain in suspension through the action of gas hold-up,
thus increasing the dissolved oxygen concentration beyond the
needs of the bacteria.
Uniaueness of the Invention
1) The present invention operates in biological
processing ranges that differ from traditional wastewater
treatment systems.
The present invention utilizes a Mean Cell Residence Time
(MCRT) ranging from 30 days to over 150 days, while the
traditional systems cannot achieve such high residency.
The Food to Microorganism (F/M) ratio sustained by the
current invention, supporting its efficiency values, are
substantially in the 0.05 to 0.80 range, versus a restricted
ratio range as recorded with various traditional systems.
The present invention uses a wastewater treatment plant
with a unique design so as to treat the total BOD portion of
the wastewater using less energy by the plant's processing
operation. This treatment is designed to significantly
reduce, if not eliminate, all biodegradable solids. The
unique process is able to perform at such an efficient level
due to the effectiveness of the aeration and recirculation
processing introduced throughout the treatment cycles.
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A traditional wastewater treatment plant's design
objective is to physically remove as much of the solid
materials from the influent flow as possible and to ultimately
dispose or waste the solids removed from the treatment system
off premises. The balance of the wastewater is treated by
various means to varying degrees of cleanliness, appropriately
meeting the levels required for the discharge.
2) The current invention uses a clarification
vessel design with a conical shaped vessel bottom in which to
collect the settled solids without the use of mechanical means
to concentrate the settled solids.
Wastewater within the vessel is made to rotate at a
sufficiently slow velocity to cause the sludge to settle,
while not providing an opportunity for the sludge to adhere to
the side of the cone shaped bottom. The velocity of the
rotating solids remain slow enough to allow them to settle and
not remain in suspension. This is accomplished by means of a
solids accumulator induction system used in the clarifies for
a controlled rotational travel of the vessels liquid.
A traditional clarifies has a mechanical device to
transport the sludge into the sludge pump's sump area for
removal. The mechanical means consist of a motor, gear
reducer, rake arm, blade and scraper squeegees and a skimmer
arm.
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3) The present invention (in the preferred
apparatus embodiment) substantially utilizes typical vessel
construction and outfitting. This allows for changes in
vessel utilization for different processes. All of the
vessels are substantially of the same size and shape to allow
the vessels to be used as a single processing zone. An
example of use as a single processing zone would be using all
the vessels as aerobic reactors during start-up procedures.
All the vessels are substantially plumbed the same, and have
substantially the same capabilities (if so desired). The
system has built-in redundancy capabilities in that each of
the vessels being of the same size and shape allows for any
one of the vessels to be used for any process, which is
desirable during times of maintenance. Vessel and plumbing
configuration is such that any processing zone has the ability
to be expanded incrementally by simply duplicating a process
vessel and plumbing as necessary to satisfy performance and/or
discharge permit requirements. With plumbing and vessel
configuration, allowances are available for a choice of vessel
processing utilization with little or no operational
shutdowns. Simple valve changes make this possible.
4) The present invention utilizes the RCAS system's
velocity, volume and direction of flow, at its discharge point
into the vessel, to regulate the rotational speed and travel
time for mixing and/or settling of solids in each zone. For
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example, an aerobic reactor could be converted into an aerobic
digester by:
Isolating the aerobic reactor from the system and
aerating the contents while holding the contents for complete
digestion of solids.
Slowing the rotational velocity in the anoxic selector so
as to allow solids to settle for transfer to the anaerobic
conditioner.
Slowing the rotational velocity in the anaerobic
conditioner so as to allow solids to settle for transfer to
the aerobic digester.
Holding the contents of the aerobic digester while
aerating so as to nearly complete the digestion of organic
matter.
Stopping the aerobic digestion action, allowing any
inorganic matter to settle to the cone bottom and then
removing any inorganic matter for disposal.
Starting the process once again for continued digestion
of organic solids.
Upon completion of all organic digestion, the aerobic
digester can be returned into service as an aerobic reactor.
5) The present invention reduces the number of pathogenic
organisms within a wastewater through the use of the RCAS
system. This occurs as the turbulence and agitation within
the toroidal vortex of the RCAS device creates a violent
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action, sheering the cell membrane of bacteria such as e. coli
and fecal coliform allowing the electron acceptors of the
bacteria to be used by oxygen which then oxidizes the bacteria
killing it.
Although illustrative embodiments of the present
invention have been described herein with reference to the
accompanying drawings, it is to be understood that the
invention is not limited to these precise embodiments, and
that various other changes and modifications may be effected
therein by one of ordinary skill in the art without departing
from the scope or spirit of the invention. For example, the
use of square or rectangular processing vessels having flat or
slopped bottoms, as is the case in traditional processing
vessels are able to be used with effectiveness by the RCAS
system. The biological process of the present invention
functions with sufficient circulation, agitation, aeration and
homogenization apart from the RCAS system.
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