Note: Descriptions are shown in the official language in which they were submitted.
'~f~ 2~ 3
W-873
METHOD OF MONITORING CONTAMINANTS IN
INDUSTRIAL WATER SYSTEMS
FIELD OF THE INVENTION
The present invention relates to industrial water systems
and specifically to the monitoring of contaminants present in the
water used in various industrial processes.
BACKGROUND OF THE INVENTION
Many industrial operations require the use of water in
the processing of their ultimate product. One such operation is
a paper mill which employs water for dilution and washing of the
cellulose fibers or pulp. The water-laden pulp is then displaced
onto a paperforrning surface. By gravity, vacuum or a combination
of both the water is then removed from the pulp leaving the cellu-
losic fibers to form the paper sheet.
J ~ ~ ~
The raw water brought into the mill, often referred to as
the mill supply water, contains numerous elements which are in
their dissolved state. Of particular interest are iron and
manganese which can form deposits that foul piping or showers,
resulting in inefficient washing and loss of paper brightness.
In addition, iron oxide formed as a result of corrosion of system
piping can be picked up and transported by the water into the
pulp or paper making process.
Other negative consequences of having water high in metal
cations content include the pluggage of wires and felts in the
paper forming section as well as the pluggage of critical
cleaning showers.
Conventional detection techniques primarily involve
taking samples of the mill supply water for elemental analysis.
This process usually requires the removal of the sample from the
site for lab analysis elsewhere. Until this analysis is
completed, there is no short term feedback, not even visual, to
the mill operators regarding the condition of the water supply.
An additional problem with conventional water monitoring
techniques is that they analyze only the mill supply water at
intake. This may adequately provide values for characterizing
the raw water but water characteristics change as the water
proceeds through the various stages of mill processing. Monitor-
ing the raw water intake does not take into consideration the
~ ~7~7~
fact that the chemistry of the water changes with increasing
temperature, pH fluctuation and/or the addition of an oxidant such
as chlorine. All three of these factors take iron and manganese
into a precipitative state and result in accelerated corrosion on
the metallic internal surfaces of the papermill piping. For
example, increased temperatures will accelerate the removal of
iron also known as "iron throw", from these metallic surfaces.
Thus, monitoring only the water intake fails to recognize the
increase in various harmful contaminants, such as iron and
manganese, occurring in the water after certain stages oF the
papermill process.
Additional contaminants which can foul industrial water ;
systems are bacteria, fungi and algae. It is desirable in these
water systems to be able to detect the presence of these
contaminants before they can deposit on various equipment surfaces
and multiply into large masses of biofilm. These biofilm masses
may impede the flow of water through pipes, conduits and channels
as well as generate offensive odors. In addition, there is a type
of filamentous iron loving bacteria which generates undesirable
iron by-products.
It is an object of the present invention to provide a
means for detecting the presence of specific contaminants or their
by-products in the water supply of a papermill within a short
period of time, not only at the point of raw water intake but also
at various stages throughout the entire papermaking process. It
is a further object to provide paper mill operators with
qualitative and semi-quantitative analyses of the water used
throughout mill operations.
~2~73
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a method for detecting the
presence of contaminants in the water used in the manufacture of
paper in a paper mill. It consists of a bag securely fastened to
S the end of a pipe or conduit which transports water. The water
passing through the conduit exits the end where the bag is
attached. The bag acts as a filter which traps certain contami-
nants in its fibers. The bag may then be removed after a pre-
determined period of time, such as from about 1 hour to 5 days,
and cut open to expose its inside surface. The appearance of the
inside surface, which will be stained to some degree, will provide
a qualitative analysis of the condition of the water which passed
through the bag during the time it was attached to the end of the
conduit. The bag may then be subjected to laboratory analysis to
determine the specific content of the contaminants.
The bag is intended to be employed as an on-line device.
It may be secured to the-ends of water conducting conduits through-
out various locations in the paper mill by a hose clamp or other
suitable means. Ideal locations include raw water intake and
after clearwell. It functions in mill water systems of from
ambient (room temperature) to 225F (i.e., through the steam
phase of water).
2 ~
The bag has been found to pick up elements such as sili-
con, iron, aluminum, potassium, calcium, manganese, titanium and
sulfur The presence of the majority of these elements must be
determined by laboratory analysis. However, the presence of iron
and manganese may be qualitatively determined because they leave
a discoloration on the internal surface of the bag. Iron will
stain the bag yellow, red, brown or shades thereof. Manganese
will stain black, gray, brown or shades thereof. This fact is
extremely helpful to the mill operator because the early detection
of these contaminants in either the mill supply or at other
locations permit the timely application of treatment programs to
control contaminant concentration. Iron and manganese will not
only stain the finished paper product affecting product quality
but they will deposit in the felts resulting in increasingly
reduced drainage, thereby slowing production and necessitating
frequent downtime for cleaning.
The material found to be most effective from which the
bags may be made is polypropylene. It is naturally white in
color. Although a felt-type weave will work, the preferred
texture is woven or spun. Representative material may be procured
from Menardi-Criswell of Augusta, Georgia. Such material may be
spun or woven, weigh from 10.0 to 18.0 ounce per yard, have a
thread count of about 70 x 32 per square inch and consist of a
weave having flow through characteristics of from 4 to 25 CFM.
- - "
The polypropylene material is configured into a substan-
tially cylindrical bag shape having an opening at one end. The
open end should be slightly larger than the outer diameter of the
water conduit to which it is to be fitted. Most conduits will be
in the range of 1/2 to 3/4 inch. Water in larger conduits can be
tested by "bushing" down the end of the conduit to about 1/2 to
3/4 inch. The length of the bag from its open end to its opposite
closed end may be from about 2 to about 6 inches. Preferably, the
bag length is from about 4 to 6 inches.
The technique used to determine the content of the
elements deposited on the internal surface of the polypropylene
bag is referred to as Scanning Electric Microscopy/Energy
Dispersive X-ray Analysis (SEM/EDXA). The Scanning Electron
Microscope is a well known electron beam instrument which is used
to visualize the surface of conductive, vacuum tolerant samples.
Energy Dispersive X-ray Analysis is a non-destructive micro
analysis technique which collects and processes the elemental
x-rays generated from the interaction between the electron beam
and the specimen at the surface of a sample. EDXA can provide
qualitative and semi-quantitative information for elements from
sodium to uranium in atomic weight. Carbon, oxygen and other
elements with an atomic weight less than sodium are not detected
by EDXA.
"Semi-quantitative" refers to the fact that peak counts
for the detected elements are normalized to 100% so that each
element is represented as being a percentage of the total of all
elements detected on the section of the material tested.
2, ~ 3
The bags are also useful to collect bacterial and other
such deposits. Bacteria having a filamentous structure such as
iron and manganese bacteria, as well as actinomycetes are readily
entrapped by the fibres of the bags. Fungi and algae are also
easily trapped. Microbial biofilms will colonize and grow on the
fibers, thus enabling analyses of biofilm growth rates and
composition.
Microbiological residue may or may not exhibit a visible
deposit. Therefore, the best means of detecting the presence of
such activity is to examine the bag fibers by use of a microscope
on other such magnification device.
Examples
Example No. 1
The method of the present invention was field tested at
a midwest papermill. Polypropylene bags measuring approximately
4 inches long and capable of fitting over a 3/4 inch conduit were
used. The material for the bags consisted of spun polypropylene,
weighing 12.3 oz/yd. and having a thread count of 70 x 32 per
square inch. It consisted of a 2 x 2 twill weave with a porosity
rating of 6 - 10 CFM. Bag No. 1 was installed at the deinker
where the water temperature was 95F; Bag No. 2 a~ the paper
machine (temperature: 95F) and Bag No. 3 at the mill water
line (temperature: 60F). Bag No. 1 was on-line for a period
of 5 hours while bags 2 and 3 remained for 6 hours.
. ,,
2.~ fj
The three samples were then subjected to SEM/EDXA. In
order to prepare the samples for analysis, sections of the
polypropylene bags were cut out and the material unraveled to
loosen the deposits. The deposits were mounted on separate
specimen stubs using double-sided carbon tape. SEM/EDXA spectral
data were collected from several separate areas in order to give
a fair representation sf the general overall composition of the
deposits. The qualitative and semi-quantitative results are
shown in the following three tables.
TABLE I
Baq #1
Relative
Element Wt. % (1)
Ca 66
Fe 14
Si 4
Mn
P 3
Cl 3
Ti 2
K
Al
~21~ ~
TABLE II
Baq ~2
Relative
Element Wt. % (1)
Ca 66
Fe 17
Mn 5
Si 3
P 3
Al 2
Ti 2
Cl ~1
TABLE III
Baq #3
Relative
Element Wt. % (
Fe 53
Ca 19
P 15
Mn 6
Si 3
Mg
Al <1
Cl <1 - ~::
Ti <1
(1)Relative weight percent does not total 100% due to rounding
off of the individual values.
2 ~ 7 3
-10-
As indicated by SEM/EDXA analysis, bag #3, installed to
monitor the cooler 60 water, had the lowe~t weight percent of
calcium. This coincides with the fact that calcium solubility
rates decrease with increasing temperature.
ExamDle No. 2
Nine different polypropylene bags, having the same construc-
tion as defined in Example No. 1, were installed at various locations
throughout three different Midwestern paper mills. After removal the
samples were first placed under a microscope and analyzed for micro
biological deposits. They were then subjected to the SEM/EDXA
procedure for semi-quantitative elemental analysis.
The sample bays are identified as follows:
A) Paper mill 2, untreated well water
B) Paper mill 2, tower water
C) Paper mill 2, well water treated with chlorine
D) Paper mill 2, warm mill water
E) Paper mill 2, "soft" well water
F) Paper mill 3, "coating kitchen"
G) Paper mill 3, paper machine hot water tank
H) Paper mill 4, heated raw water
I) Paper mill 4, ambient raw water at pump house
~ " '
~1~ h ~ 7 3
The bag samples were first analyzed for microbiological
content. The results are as follows:
Sample Comments
A Small amount of bacteria present.
B Iron bacteria (Gallionella ferrugina) present along with
non-sheath forming bacteria.
C Both sheath and non-sheath forming bacteria present.
D Both sheath and non-sheath forming bacteria present.
E Very few bacteria present; appearance clean.
F,G Large presence of iron bacteria (G. ferrugina).
H,I Large amount of algae (diatoms) present. Lesser amount
of both sheath and non-sheath bacteria.
:
These samples were then submitted for SEM/EDXA analysis
according to the procedure described in Example 1. The semi-
quantitative elemental results normalized to 100% (+ 10%) are
shown under each sample identification.
A B
ElementWt.% Element Wt.%
Mn 79 Mn 33
Fe 11 Fe 28
Ca 7 P 15
Ba* 2 K 14
Si trace< 1 Ca 8
P trace< 1 Ti* 3
-12-
C D
Element Wt.% Element Wt
Fe 39 Fe 31
P 34 P 27
Ca 14 Ca 16
K 10 K 12
Mg trace ~ 1 Mn 10
Cl 3
Si
E F
Element Wt.% Element Wt
Mn 43 Fe 46
Fe 19 P 27
K 18 Ca 21
P 7 Mn 6
Ti~ 5
S 5
Si 2
G H
Element Wt.% Element Wt
Fe 51
P 22 Fe 25
Ca 19 K 21
Mn* 6 Si 20
Mg 1 Ca 14
P 13
Al
S 3
-13-
Element Wt.%
Si 38
Fe 21
Ca 16
K 9
Al 6
Mn 2
Cl 2
S I : .
By the method of the present invention papermill operators
are permitted to determine very quickly, on a qualitative basis,
whether certain contaminants, specifically the troublesome
elements iron and manganese, as well as various microbiological
species, are present in the location where the water is being
tested. Testing may be done on an on-line basis and does not
require the extraction of a water sample. The polypropylene bag
used to entrap the aqueous contaminants may first be subjected to
a visual or microscopic evaluation and then to SEM/EDXA analysis
to determine the relative concentrations of the elements in the
sample tested.
