Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~2~2
CATIONIC POLYMER FOR WATER CLARIFICATION
AND SLUDGE DEWATERING
FIELD OF T}IE INVENTION
The present invention pertains to the use of a particular water
soluble cationic homopolymers of a specific intrinsic viscosity range
for water clarification and for sludge dewatering.
The homopolymers are obtained from the polymerization of
cationic monomers, namely quaternization products of dimethylamino-
ethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl
acrylate and N,N-dimethylpropyl methacrylamide.
BACKGROUND OF THE INVENTION
A difficult problem in industry is the clarification of
industrial wastewaters. Much too often these waste waters contain
finely di~ided solids and when allowed to flow into lakes and streams,
add to water pollution.
It is highly desirable to remove these finely divided solids
from industrial wastewaters so that these waters can be discharged
into the environment without the risk of harmful pollution.
As detailed in Kirk-Othmer: Encyclopedia of Chemical
Technology Volume 10, Third Edition, pages 489-5~3, clarification of
an aqueous system suffering from finely divided solids consists of
three distinct steps: coagulation, flocculation and sedimentation.
Coagulation is the process of neutralizing the charge on the
suspended particles, allowing them to be brought together. Floccu-
lation is the process of coagulating these neutralized particles to
form an agglomeration. Lastly, sedimentation refers to the settling
. , ~ ..: , ~ : ~ : , . :: : . :.
" ' I' ; "'. '~ ' '' ' ' ,' ~ ' ~
.: ~ . - : : :, :. :
,. : , ::
of the coagulated particles which can then be removed by mechanical
means if necessary.
Metal coagulants are often used to treat wastewaters but they
can cause problems in pH control and carryover of metallic light flocs
downstream. Polyelectrolytes are high molecular weight electrolytes
in polymer form that do not have these limitations.
It has been found that certain water-soluble organic polymers
with numerous sites for coagulation along the polymer chain allow for
clarification of an aqueous based system.
The use of cationic polymers for wastewater treatment is known
in the art. As cited in "Polyelectrolytes for Water and ~astewater
Treatment" chapters 6 and 7 (W.L.K. Schwoyer, CRC Press, 1981), it is
gcnerally believed that in settling and flocculation, there is a rela-
tionship between molecular weight and effectiveness, with the higher
molecular weight polymers of a given type being the most effective.
U.S. Patent 4,699,951 (Allenson, et al) discloses a combination
of two cationic polymers with vastly different molecular weights for
treating water contaminated with oily waste and dispersed solids. The
application and method of treatment differ from the present invention
in that it is a polymer admixture that is applied to the wastewater.
Other patents of interest include U.S. Patent Numbers 3,336,269
(Nonagle et al.) and 3,336,270 (Monagle). These disclosures pertain,
inter alia, to preparatory routes for acrylamide type water soluble
polymers in general and detail the preparation of acrylamidejvinyl
quaternary ammonium salt copolymers, such as betamethacryloyloxyethyl-
trimethyl ammonium methyl sulfate/acrylamide copolymers. Another
patent related to the general field of flocculation is U.S. Patent
3,278,506 (Chamot et al.).
,: :- . . . : -
: . . :.
::
' : : :
~ 3 ~ ~ ~ ~2~2
In contrast to the prior art disclosures, we have found that a
polymer oE methacryloyloxymethyl trimethyl ammonium chloride (METAC)
is surprisingly effective in clarlfying water that has fine solids
dispersed in it.
In the sedimentation step, the coagulated particles accumulate
as sludge at the bottom of the vessels wherein the water clarification
takes place, which sludge is generally removed continuously or at
predetermined intervals. However, the sludge removed from the vessels
contains large amounts of water and must be dewatered before disposal.
With the increasing concern over pollution problems, sludge
dewatering has become an essential part of wastewater treatment pro-
grams. No longer can untreated sludge simply be dumped into the
nearest river, lagoon or vacant lot. With this environmental interest
in mind, improved sludge concentrating and dewatering techniques have
become an important task in the water treatment industry.
Generally, sludge is given primary dewatering treatment before
belng discharged from any given process system. Primary dewatering is
usually accomplished using thickeners/clar~fiers or settling ponds.
Secondary dewatering, including vacuum filtration, centrifugation,
belt filters, lagoons, etc., is then commonly employed to further
increase the solids content and reduce the water content in the
resulting sludge to 50 to 90~ liquid. This can cause sludge
dewatering to be a slow process.
In sludge handling ~acilities, problems often encountered in
the dewatering process include the formation of sludge cake with high
moisture content, poor cake release from dewatering equipment, high
disposal costs, slow dewatering and poor equipment ef~iciency.
Improved sludge dewatering can lead to increased savings,
especially with respect to the costs associated with transportation of
the sludge to be disposed.
. , ~ ~ .. ~ : .: ,-
: .:- - ~ . . .: ..
.
~:
Uater soluble polyelectrolytes, such as anionic and cationic
polymers, are often added to the sludge to ald in the production of a
drier cake and in the reduction of wear and tear on dewatering
equipment.
As detailed in the Betz Handbook of Industrial Water
Conditioning, 8th Edition, 1980, Betz Laboratories, Inc., Trevose, PA,
pages 253-256, cationic polymers can increase the settling rate of
bacterial floc. These polymers further improve capture of the
dispersed floc and cell fragments. By concentrating solids more
quickly, the volume of recycle flow can be minimized so that the
oxygen content of the sludge is not depleted. Further, the waste
sludge is usually more concentrated and will require less treatment
for eventual dewatering.
U.S. Patent 3,023,162 (Fordyce, et al.) describes a homo-
polymer of dimethylaminoethyl methacrylate quaternized with ethylene
oxide or propylene oxide for dewatering. The precise structure of the
resulting polymers after reaction is not identified. Polyalkylene
oxide is usually formed from this type of reaction and may be attached
to the amine site. This differs from the present invention in that
the quaternization is achieved by the use of alkylene oxides.
U.S. Patents 4,319,013 and 4,396,752 (Cabestany et al.) teach
that a cationic copolymer of acrylamide and quaternized dimethylamino-
ethyl acrylate can be used for dewatering. The effective copolymer is
in powder form and has an intrinsic viscosity higher than 6 dl/g. The
present invention differs in that the polymer is a homopolymer in
solution form having an intrinsic viscosity less than 6 dl/g. In con-
trast to the Prior Art, this polymer shows an unexpected improvement
in soluble dewatering.
U.S. Patent 4,395,513 (Haldeman) discloses the use of a
cationic copolymer consisting essentially of acrylamide (10-20%)
'' : . ' : ::: ` : : :: .:
:: ~ ` ` ~ ` :: : :
., . ~`:
,: :
' ,:: ~ ' : ~
': ::
/N,N - dimethylaminoethyl methacrylate methyl chloride (90-80%) with a
molecular weight about one million and an intrinsic viscosity of at
least 5 dl/g for biological sludge dewatering. This patent also
states that the copolymer performs better than the 100~ cationic
homopolymer in the test conducted.
U.S. Patent 4,699,9Sl (Allenson et al.) discloses a combination
of two cationic polymers with vastly different molecular weights for
treating water contaminated with oily waste and dispersed solids. The
application and method of treatment differ from the present invention
in that it is a polymer admixture that is applied to the wastewater.
One problem with these anionic and cationic polymers is that
their operating parameters are limited. The addition of too much of
these dewatering agents can cause the solids to disperse and defeat
the whole purpose of dewatering.
Uith the foregoing in mind, the present inventors embarked upon
a comprehensive study in an attempt to dewater sludge in a more
efficient fashion.
Accordingly, the present invention is directed to a process of
clarifying wastewater by adding to water that has suspended solids
present, a clarifying cationic homopolymer of a specific intrinsic
viscosity and to the use of particular water soluble cationic
homopolymers of a specific intrinsic viscosity range for sludge
dewatering.
The cationic homopolymers comprise a repeat unit having the
structure: . R
~
- CH2 ~ I ~
C = O
o
lH2
CH2
CH3 - N+ - CH3 Cl-
CH3
:: : : .. :.: :
:
;. -~ :
i ~ :
- 6 -
The water clarifying homopolymer is obtained from the
polymerization of the cationic monomer, namely quaternization product
of dimethylaminoethyl methacrylate and the homopolymers for sludge
dewatering are obtained from the quaternization products of
dimethylaminoethyl methacrylate, diethylaminoethyl acrylate,
dimethylaminoethyl acrylate, and N,N-dimethylpropyl methacrylamide.
DETAILED D~SCRIPTION OF THE INVENTION
In accordance with the invention, a cationic homopolymer
comprising the polymerization products of ethylenically unsaturated
cationic monomers such as quaternized dimethylaminoethyl methacrylate
and dimethylaminoethyl acrylate, at an intrinsic viscosity range of
1.0 to 4.5 dl/g, preferably 1.0 to 4.0 dl/g, more prefera~ly 1.0 to
2.0 dl/g is unexpectedly effectiv~ in water clarification.
The cationic homopolymer which has proven to be most effective
as a clarifying aid for water that has suspended solids ln it,
comprises repeat unit moieties having the structure:
CH3
¦- CH2 ~
C = O
o
CH2
2s
IH2
CH3 - N~ ~ CH3 Cl- - -
CH3
Furthermore, catlonlc homopolymers comprising the
polymerizatlon products of ethylenically unsaturated cationic monomers
such as quaternized dimethylaminoethyl methacrylate, diethylaminoethyl
acrylate, dimethylaminoethyl acrylate, N,N-dimethylpropyl
methaerylamide, and N,N-dimethylpropyl acrylamide, etc. are
unexpectedly effective in sludge dewatering at an intrinsic viscosity
35 range of 1.0 to 4.5 dl/g, preferably 1.5 to 4.0 dl/g, more preferably
1.5 to 2.0 dl/g.
.: ,: . . :.
.: , .. : ~ . .. .. . ...
' ' ' ~ .: " '
' ',
'. ' ~ ' . . ' .
',
:
'' . '
. I
- 7
The described cationic monomers are obtained from a quater-
nization reaction of the respective monomers with alkyl or aryl
halides such as methyl chloride, methyl bromide benzyl chloride, or
dimethyl sulfate. The resulting cationic monomers are then
polymerized by conventional polymerization techniques. Any of the
well known initiators such as azo compounds, peroxides, redox couples
and persulfates may be used to polymerize the catlonic monomers.
Radiation, thermal or photochemical polymerization methods may also be
used to yield the polymers. Likewise, for those skilled in the art,
any method such as chain transfer agents, concentration, temperature
and addition rate variations may be used to regulate the viscosity or
molecular weight of the resulting polymers. The polymerization may be
conducted in solution, suspension, bulk or emulsion. In the emulsion
polymerization, a water-in-oil inverse emulsion technique as disclosed
in U.S. Patents 3,284,393, Reissue 28,474 and Reissue 28,576 is
preferred. The reaction will generally occur between 20 and 100C,
pending the initiation system and polymerization medium used. The pH
of the reaction mixture is generally in the range of 2.0 to 7Ø
Higher pH will cause the hydrolysis of the cationic monomers.
The preferred method in accordance to the invention is to
polymerize each cationic monomer in an aqueous medium using persulfate
as an initiator at 80 to 95C and at a pH of 2.0 to 4Ø The desired
viscosity of the polymer is regulated by adding a proper amount of
persulfate, cationic monomer and water during polymerization. The
resulting polymer is verified by viscosity increase, light scattering
measurement and carbon 13 nuclear magnetic resonance (NMR)
spectroscopy. Intrinsic viscosity of the polymer is measured in 1 M
sodium chloride solution at 30C. The Huggins equation is used to
determine the intrinsic viscosity. According to established theory
and equations in the art, intrinsic viscosity values can be correlated
with the molecular weight of the polymer. A higher intrinsic
viscosity of the polymer will represent a higher molecular weight.
This is illustrated in Billmeyer's "Textbook of Polymer Science" pages
- . , ~.- ~ , , .: ~, ,
: ...... : - : , ;
" , . ~ . . . - ,
- : : ., , ~ .
: :
- : . . . : . :
.
- 8
208 to 213 (1984). Intrinsic viscosity of the polymers in accordance
with this invention is about 1.0 to ~l.5 dl/g, preferably 1.5 to 4.0
dl/g, more preferably 1.0 to 2.0 dl/g.
The poly~er for water clarification ls added to the selected
substrate in an amount of about 1 to 50 ppnl active, preferably 2 to 10
ppm active. The polymer may be added to the substrate prior to
entering the secondary clarifier, or to the clarifier centerwell.
The specific homopolymer which has proven to be most effective
as a dewatering aid comprises repeat unit moieties having the structure
r l 1
l- CH~ - C - J
C = 0
lH2
IH2
Ctl3 - N~- CH3 Cl
CH3
wherein R is H or methyl.
The method of preparation of the homopolymer methacryloyl-
oxyethyl trimethyl ammonium chloride (METAC) designated as Samp]e
Number 1 in Table I is detailed below.
A suitable reaction flask was equipped with a mechanical
agitator, a thermometer, a condenser, a nitrogen inlet and addition
30 inlets for reagents. The flask was charged with 40.0 g of 75~ METAC
and 20 g of deionized water. The resulting solution was heated to
90C under a nitrogen ~lanket. An initiator solution containing 0.5%
of sodium persulfate in deionized water was prepared separately and
sparged with nitrogen. The initiator solution (7.5 g) was then added
35 to the reaction flask over 270 minutes at 90C. Three 20 g aliquots
of deaerated, deionized water were added to the reaction at the 30, 90
,
:
2~2~
g
and 210 minute addition intervals. The reaction was held at
temperature for 60 minutes followed by the addition of 120 g of
deionized water. After mixing at 90C for another 30 minutes the
reaction mixture was cooled to room temperature.
The homopolymer solution, after being diluted to 10.6% solids,
had a Brookfield viscosity of 1160 cps. The resulting product was a
clear solution with a pH at 3.3. The structure of the polymer was
verified by C 13 NMR. Tlle structure was characteri~ed by a broad
polyacrylate type backbone and no evidence of unreacted monomer.
Intrinsic viscosity of the polymer was 1.5 dl/g as measured in 1 M
sodium chloride solution at 30 C.
The polymer is added to the sludge to be treated in an amount
of about 80 to 600 ppm active, preferably 100 to 350 ppm active.
These dosages correspond to about 5 to 40 pounds active polymer per
ton of dry sludge, based on an average sludge solids of 3~. The
polymer may be added directly to the sludge after it has been
clarified.
The polymer may also be added after the sludge has been
subjected to a thickener, digester or the like. The polymer may also
be added to the sludge prior to other dewatering processes such as
belt filters, vacuum filters, centrifuges or lagoons.
Compounds such as alum, ferric chloride, anionic polymers such
copolymers of acrylamide with acrylic acid, 2-acrylamido-2-
methylpropylsulfonic acid or styrene sulfonate etc., and other
cationic polymers for example, polydimethyldiallyl ammonium chloride
(DMDAC); condensation product of epichlorohydrin with alkylamines;
copolymers of acrylamide with DMDAC, methacryloyloxyethyl trimethyl
ammonium methacrylate (METAMS), methacrylamido propyltrimethyl
ammonium chloride, (MAPTAC), acrylamido propyltrimethyl ammonium
chloride (APTAC), acryloyloxyethyl trimethyl ammonium chloride
(AETAC), methacryloyloxyethyl trimethyl ammonium chloride (METAC),
"" ~ "
~ ~ :
.. ' ' ' . ` :
- 10 -
acryloyloxyethyl diethylmethyl ammonium chloride or their methyl
sulfate quats may be used in conjunction with the polymers in this
invention for sludge dewatering or for water clarification.
BRIEF DESCRIPTION OF THE DRAWINGS
The appended drawings graphically present the data generated by
the examples which are reported hereinbelow. In the Drawings:
Figure #l is a graph showing the settling rate versus the
dosage of samples tested in Table I.
Figure #2 is a graph showing the compaction rate versus the
dosage of samples tested in Table I.
Figure #3 is a graph showing the supernatant turbidity versus
the dosage of samples tested in Table I.
Figure #4 is a graph showing the settling rate versus the
dosage of samples tested in Table II.
Figures #5 is a graph showing the comparison rate versus the
dosage of samples tested in Table II.
Figure #6 is a graph showing the supernatant turbidity versus
the dosage of samples tested in Table II.
Figure #7 is a graph showing the capillary suction time of
various conditioned samples tested in Table III.
~.
Figure #8 is a graph showing the capillary suction time of
other conditioned samples tested in Table III.
:
: :- : . , :-, .:
, ~ r
Figure #9 is a graph showing the percent caked solids of
conditioned samples tested in Table IV and V.
Figure #lo is a graph showing the percent solids captured of
conditioned samples tested in Tables IV and V.
Figure #11 is a graph showing the percent caked solids of
conditioned samples tested in Table VI.
Figure #12 is a graph showing the percent solids captured of
conditioned samples tested in Table VI.
Figure #13 is a graph showing the percent cake solids of
conditioned samples tested in Table VI.
Figure #14 is a graph showing the percent solids captured of
conditioned samples tested in Table VI.
Figure #15 is a graph showing the percent cake solids of
conditioned samples tested in Table VII.
Figure #16 is a graph showing the percel~t solids captured of
conditioned samples tested in Table VII.
EXAMPLES
The following examples are illustrative only and should not be
construed as limiting the invention.
Water Clarification
Example 1 Preparation of Methacryloyloxyethyl Trimethyl
Ammonium Chloride Homopolymer (METAC)
, , ., , ~" , :,, . ~ :
. :~ - ; . : : .:
~: .
':. : ,
~2~2
- 12 -
To a suitable reactor was charged 339 parts of METAC (75~),
501.5 parts of deionized water and 8.0 parts of ethylene diamine
tetraacetic acid solution (6.25%, disodium salt). The reactor was
purged with nitrogen and the solution was then heated to 190F. 41.22
parts of a 0.81~ sodium persulfate solution was then added to the
solution over three hours at 190F. After that, the resulting viscous
solution was diluted with water and cooled down.
The final product was a clear solution with a p~l of 2.92 and a
10 Brookfield viscosity of 9,020 cps (20.2% solids). No residual monomer
was detected by carbon 13 nuclear magnetic resonance measurement. An
intrinsic viscosity of 1.8 was measured in 1 M sodium chloride
solution at 30C.
Table A below presents a summary of the physical properties of
the resulting polymer.
TABLE A
Polvmetac Properties
Brookfield
Viscosity, Intrinsic
25Example% Solids cps, at 25C ~ Viscositv. dl/~
1 20.2 9,020 2.92 1.8
Comparative clarifying tests were also performed using
well-~nown cationic polymers described in the prior art. Their
properties are described in Table B.
,~ , .
.
~: ,. . . : ~: :
, ~, , ,
- 13 - 2~421~
TA~LE B
Comparative Polymers
5 Comparative Intrinsic Viscosity
Polymer Desi~nation Description dl/g
A Polydimethyldiallyl 0.8
Ammonium Chloride
BEpichlorohydrin/Dimethyl 1.0
Amine
CYLINDER SOLIDS SETTLING TEST
The secondary clarification activity of the proposed invention
was evaluated by conducting cylinder settling tests with aeration
basin effluent obtained from two sources in the Midwestern United
States, one chemical and one plastics manufacturer. Substrate used
for conducting the cylinder settling tests at each test site was
diluted to eliminate cylinder wall effects on settling and compaction
rates. For the tests conducted with the substrate from the plastics
manufacturer, the dilutions were made with water at a ratio of 1:1.
The substrate obtained from the Chemical Manufacturing facility was
diluted 1:3 with the plant's tertiary effluent.
The use of effluent from the waste treatment system for
dilution is preferable to tap water since it will affect the least
change on test substrate behavior. Treatment performance was
evaluated based on solids settling and compaction rates as well as
final supernatant turbidity valves. ~le solids settling results would
be analogous to the rate at which the solids would separate from the
waste stream upon entering the secondary clarifier.
.:: . .... . :
,, : . ~ :
,
. : -:: ' ' .: '
` 2~2~2
- 14 -
The solids compaction results are an indication of how dense
the sludge bed in the secondary clarifier would become with the use of
a particular treatment. Supernatant turbidity values would also
indicate the performance of the treatment with respect to final
secondary clarifier effluent.
Letters A and B represent the comparative polymer results while
number l represents the homopolymer of the present invention.
The results of these tests appear in Table I and II.
:: : .. . : . :
- . ~ :: ,: :
,
'' ' `~'
- 15 ~ 2
TABLE I
C~linder Solids Settling Test Results
Substrate Source: Mid-West Chemical Manufacturer
Substrate: Aeration Basin EfEluent
Substrate Suspended Solids: 5,740 ppm
Substrate p~l: 6.42
Substrate Volume: 500 m~0 Test Procedure: Premix substrate by inverting sample 3 times.
Add treatment and invert sample 5 times.
Record time for solids interface to travel between the
450 and 300 mL graduations for determining settling
rate. Record time for solids interface to travel
between the 300 and 200 mL graduations for determining
solids compaction rate.
Supernatant Turbidity values were measured after
completion of the settling and compaction rate tests.
Dosage Settling Compaction Supernatant
Treatment (ppm. active) ~ CC~ Rate mm/sec Turbiditv tNTU)
"A" 0.38 1.49 1.05 20.0
0.76 1.87 1.15 13.2
0.95 2.32 1.05 12.6
1.14 2.49 1.25 14.0
1.52 2.23 1.43 26.0
"B" 1.00 2.00 1.40 17.0
2.00 2.67 1.89 12.6
2.51 3.26 2.35 12.0
3.01 3.83 2.79 12.8
4.01 4.00 3.08 13.0
"1" 0.42 1.82 1.28 15.0
0.84 2.51 1.71 10.5
1.06 2.93 2.28 10.2
1.27 3.47 2.55 10.0
1.69 3.83 2.45 9.0
,
, , . ~ . ~:: :
- , .,
: -
~2~2
- 16 -
TABLE II
Cylinder Solids Settling Test Results
Substrate Source: Mid-West Chemical Manufacturer
Substrate: Aeration Basin Effluent
Substrate Suspended Solids: 2,650 ppm
Substrate p~l: 7.66
lO Substrate Volume: 500 mL
Test Procedure: Premix substrate by inverting sample 3 times.
Add treatment and invert sample 5 times.
Record time for solids interface to travel between the 450
and 300 mL graduations for determining settling rate.
Record time for solids interface to travel between the 300
and 200 mL graduations for determining solids compaction
rate.
Supernatant Turbidity values were measured after
completion of the settling and compaction rate tests.
DosageSettling Compaction Supernatant
Treatment(ppm, active) Rate mm/sec Rate mm/sec Turbidity (NTU)
"A" 0.19 0.70 0.35 4.4
0.57 0.98 0.38 2.2
0.76 1.40 0.49 2.4
0.95 1.60 0.56 2.5
1.33 1.76 0.58 2.8
1.71 2.20 0.63 3.8
"B" 0.502 1.22 0.52 7.9
1.506 2.45 1.59 3.8
2.510 4.53 2.83 4.1
3.514 6.38 3.61 4.4
4.518 6.29 3.67 5.1
"1" 0.212 1.28 0.44 2.~l
0.636 1.91 0.67 2.6
0.84~ 2.43 0.91 2.5
1.060 3.39 1.59 2.7
1.484 3.67 1.42 5.0
" ; . : : :: :
`: :: - - : :
- 17 - ~ 2
The examples demonstrate that the METAC exhibits surprlsingly
superior performance when compared to the conventional or well known
polymers as described in the prior art. This polymer promotes faster
settling rates and compaction rates which have both economic and
environmental benefits.
It would be expected that the dimethyl sulfate quat of
dimethylamino ethylacrylate homopolymer should perform similarly to
the described polymer.
Sludge Dewaterin~
SA~PLES
15 Homopolymers of (meth)acryloyloxyethyl trimethyl ammonium
chloride were prepared in aqueous solution using sodium persulfate as
an initiator at 80 to 95C. A proper amount of water was added during
the reaction to regulate the desired viscosity (molecular weight) of
the product. No residual monomer was detected by carbon 13 nuclear
magnetic resonance measurement. Intrinsic viscosity of the polymer
was measured in lM sodium chloride solution at 30C.
Table I below presents a summary of the physical properties of
the resulting polymers produced by the above method.
TABLE C
Polymetac Properties
Brookfield Intrinsic
Viscosity, Viscosity,
Sample Number Composition % Solids cps. at 25C pH dl/~
1 (1555-43) METAC 10.6 1160 3.3 1.5
2 (1555-45) AETAC 9.9 1444 2.9 1.7
3 ~1577-32) METAC 9.6 12040 3.2 2.9
4 (1485-281) METAC 3.5 114 3.5 0.86
METAC = methacryloyloxyethyl trimethyl ammonium chloride
AETAC = acryloyloxyethyl trimethyl ammonium chloride
,, ,, , .................... -,., - , , ...... , -., .
: ' : :: .~. ~ ' ' : :''
. ' . . , , :
~2~2
- 18 -
Comparative dewatering tests were also performed using the
well-known polymers described in the prior art. These are described
in Table II.
TABLE D
Comparative Pol~mers
Intrinsic
10 Polymer Description Viscositv. dl/g
A Copolymer of acrylamide/metac 8.9
B Polymetac 5.4
C Polydimethyldiallyl Ammonium Chloride 1.4
D Polydimethyldiallyl Ammonium Chloride (DMDAC) 0.8
E Polydimethyldiallyl Ammonium Chloride (DMDAC) 1.5
~EWATERING ACTIVITY TEST
The relative dewatering performance of the polymers was
evaluated by two different test methods, capillary suction time (CST)
and a laboratory belt filter press. Mixtures of primary and secondary
sludge from a pharmaceutical plant in New Jersey taken on four
different dates were used for evaluation.
In the CST test, an aliquot of sludge is placed in a cylindrical
cell which is placed on top of a piece of chromatography paper. The
capillary pressure exerted by the paper draws the water out of the
sludge. A timer records the time in seconds required for the water to
pass between two fixed points. Shorter times indicate better dewater-
ing efficacy. Results are evaluated by preparing a graph of CST
versus treatment dosage. Generally, the treatment which produces the
lowest CST value at the lowest dosage is the most effective. The
lowest CST value at the lowest dosage is the most effective. The
results appear in Figures 1 and 2 and the data used to generate these
figures is found in Table III. Letters A through E represent the
,: , , ~ , .::
: : ,
: :, . ~ , : . . :, :
2 ~ ~ 2
- 19 -
comparative polymer results, while numbers 1 through 4 represent the
homopolymers of the present invention.
A Larox laboratory scale belt filter press was the second method
employed to evaluate polymer dewatering performance. The design of
this instrument permits modeling of full-scale belt filter press
operations by adjustment of conditions such as solids loading, filter
media, free drainage time, pressure and press time. The sludge cake
produced from the laboratory scale belt filter press is analyzed for
percent solids and percent solids capture, with solids capture being
defined as the quantity of solids retained by the belt filter media
compared to the quantity of solids loaded on the press. Results are
evaluated by plotting percent solids and percent solids capture
results versus treatmer.t dosage. Higher values of percent sludge cake
solids and percent solids capture indicates a higher degree of
dewatering and better treatment performance. Dosages for conducting
evaluations on the laboratory belt filter press were selected based on
the results of the CST tests. Sludge characteristics and test
conditions are described in the Tables below. The results have been
plotted and appear in Figures 3 to 10. Data used to generate the
graphs is presented in Tables IV to VII. Letters A through E
represent the comparative polymer results, while numbers 1 through 4
represent the homopolymers of the present invention.
., 1 . .: ~ ;
;:
:
- 20 - ~ ~ ~ 2 i ~ ~
Test Conditions
Substrate Volume: 200mI.
" Solids: 2.85
" pH: 6.90
Treatment mixing: 5 seconds @ 550RPM prior to treatment addition
30 seconds @ 550RPM after treatment addition
TABLE III
Ca~il]arv Suction Time (Seconds~:
Polymer Dosage
Treatment:
(ppm, active) _ B C #3 #1 D #2
246.7 144.5
2050 143.5 60.6 304.35114.7
13.7
93.2 54.3 10.8 175.9026.0
100 84.2 64.5 52.9 22.2 6.4 44.6013.7
115 10.2
25120 62.2
125 54.3 30.4 28.6 9.5 6.8
135 22.7 7.0 23.3
150 8.2 8.0 7.3 6.9 8.0
175 7.9 12.8 13.4 7.3
30200 18.4 19.6 23.7011.5
225 25.7 29.2
250 15.908.1
300 10.308.3
350 8.4
35400 8.50 8.0
500 8.4
600 10.55
700 9.5
800 16.9011.6
:: . , ; . ::~ .: . :
,: ~ , : . : .~ . . -:
- ~ :. .
.:
- 21 - 2~21~2
Substrate Solids: 2.79%
" pH: 6.53
Loading Rate: 2~188XlOE-02 grams/cm2
Cycle: 20 seconds of Free Drainage
40 seconds @ 40 psig
Belt Cloth: Parkson P-28S (smooth side used for contact with sludge)
Blank - no cake formed
Treabnent mi~in~: 5 seconds @ 550RPM prior to treatment addition
30 seconds @ 550RPM after treatment addition.
TABLE IV
Laboratorv Scale Belt Filter Press Tests
Polymer Dosage Percent Percent
Treatment (ppm. active~Cake Solids Solids CaPture
A 100 4.85 13.94
150 5.19 21.00
, 200 7.02 36.36
250 8.30 55.00
350 7.99 53.00
D 50 5.04 7.31
100 5.23 11.63
300 8.15 39.86
450 8.77 46.09
600 7.96 44.80
B lOO 4.95 16.47
150 7.15 24.00
200 8.48 39.00
250 9.75 53.50
350 10.21 60.80
C 100 5.49 13.85
125 5.57 18.60
150 5.95 21.50
200 7.06 30.59
300 7.58 41.90
.
. . . :
'' ' : .,:
,: , ,' ':' ; ~ : '' :. ,: : '
,:
,. -
~ i .
- 22 - 3~}~21~2
TABLE IV (Cont'd~
Laboratorv Scale Belt Filter Press Tests
Polymer DosagePercent Percent
Treatment(ppm. active)Cake Solids Solids Capture
#3 75 5.20 13.28
125 6.25 20.25
150 7.11 27.99
200 9.31 55.35
300 10.15 70.34
#1 50 5.82 17.91
6.90 32.40
lO0 8.60 46.36
150 9.58 57.63
200 9.32 54.16
#2 100 5.73 14.91
150 6.15 21.20
250 ~.01 30.60
350 8.56 43,40
500 9.49 54.66
, ' ': ., ' , , - ' :', ' `: ',: ' ~ ' " . . ' ' `' ;, ' .' : ,: .
.: ' : '
.:, ~'
- 23 - ~ ~ ~ 2 ~
Substrate Solids: 2.71%
Substrate pH: 6.85
Loading Rate: 2.188XlOE-02 grams/cm2
Cycle: 20 seconds of free drainage
40 seconds @ 100 psig
Blank - no cake formed
Treatment mixing: 5 seconds @ 550RPM prior to treatment addition
30 seconds @ 550RPM after treatment addition.
TABLE V
Laboratory_Scale Belt Filter Press Tests
Polymer Dosage Percent Percent
Treatment ~ppm active~ Cake Solids Solids Capture
C 100 5.671 28.98
150 6.893 34.24
185 7.712 42.63
200 8.164 45.68
250 8.824 52.64
300 10.851 66.05
#4 100 6.757 30.69
150 6.950 34.20
185 7.311 40.01
200 7.510 45.20
250 7.965 47.90
300 8.850 51.15
#1 100 6.367 34.94
150 8.038 49.94
185 9.491 58.57
200 9.702 63.82
250 10.490 58.71
300 11.168 72.49
B 100 6.548 32.41
150 8.707 55.99
185 9.860 67.30
200 10.900 75.72
250 11.850 82.10
300 12.030 82.03
.
,
,
, ,
:
- 24 - ~ ~3 ~ 2
Substrate Solids: 2.71
Substrate pH: 6.85
Loading Rate: 2.188XlOE-02 grams/cm2
Cycle: 20 seconds of free drainage
40 seconds @ 90 psig
Blank - no cake formed
Treatment mixing: 5 seconds @ 550RPM prior to treatment addition
30 seconds @ 550RPM after treatment addition
TABLE VI
LaboratorY Scale Belt Filter Press Tests
Polymer Dosage Percent Percent
Treatment(ppm. active) Cake Solid~ Solids Capture
D 50 5.179 14.39
100 5.867 27.14
200 7.844 45.12
450 11.840 75.89
C 50 4.769 15.29
100 6.519 25.69
200 9.250 53.34
450 12.160 79.99
E 50 5.382 16.88
100 6.280 31.86
200 8.450 49.96
450 12.560 86.68
#1 50 5.356 20.58
100 7.629 40.56
200 10.684 72.64
450 12.960 97.75
#2 50 4.853 16.10
100 7.130 35.69
200 9.450 57.23
450 ll~.060 95.59
' . ' ' , :. ' ~ ' ' ' ~
': ` ' ,,
:` `: :: :
- 25 -
Substrate Solids: 2.71%
Substrate p~: 6.85
Loading Rate: 2.188XlOE-02 grams/cm2
Cycle: 20 seconds of free drainage
40 seconds @ 100 psig
Blank - no cake formed
Treatment mixin~: 5 seconds @ 550RPM prior to treatment addition
30 seconds @ 550RPM after treatment addition
T~BLE VII
LaboratorY ScaLe Belt Filter Press Tests
Polymer Dosage Percent Percent
Treatment (ppm. active~ Cake Solids Solids Capture
D lOO 5.883 19.83
150 6.822 32.85
185 7.610 36.25
200 7.953 38.02
250 8.120 38.35
C 100 5.915 24.20
150 7.138 36.58
185 7.575 43.90
200 8.180 47.80
250 9.386 54.34
30 E lOO 6.257 26.28
150 7.280 38.50
185 8.312 48.26
200 8.601 52.79
250 9.687 62.23
#1 lOO 6.889 40.71
150 8.673 47.55
185 10.253 60.03
200 10.85~ 66.35
250 11.675 75.50
.~ , , ,
. - . ~ : ~ . .-
- : :
:, : , , , ~ ~ .
-:
,
,,
~: ' ~ ,
` ~
- 26 -
TABLE VII (Cont'd)
Laboratory Scale Belt Filter Press Tests
Polymer Dosage Percent Percent
Treatment (ppm. active) Cake Solids Solids Capture
#2 100 6.013 29.39
150 7.867 43.28
185 9.389 52.56
200 10.106 54.95
250 11.762 67.45
15 The examples demonstrate that the polymers in this invention
exhibit surprisingly superior performance when compared to the conven-
tional or well known polymers as described in the prior art. The
polymers according to the invention promote higher cake solids in the
sludge dewatering tests which have both environmental and economical
benefits. They also have a wider effective dosage range as compared
to the prior art polymers making it easier to control the polymer
dosage in a treatment plant.
In accordance with the patent statutes, the best mode of
practicing the invention has been herein set forth. However, it will
be apparent to those skilled in the art that many modifications can be
made in the methods herein disclosed without departing from the spirit
of the invention.
'
.- ,............. . ~: . . - . , : , . . : : . . ~,: : : ,
:~ , :' . ~ ' ~ ` ' .' : ' .. ', :
. : ,
: : ~ `
' : : , ' ; ` ' : ~::
