Jung-Chae Park
Andrew (Dong Hyuk) Kim
5/15/2000
Discovery and Application of Transparent Exopolymer
Particles (TEP) in Cayuga Lake
Abstract
Cayuga Lake water contains a polymer that adheres
to filters. In order to prove its existence; Cayuga Lake
water was studied. Through glass fiber filters we
determined that there exists such a polymer, and
named it appropriately as Transparent Exopolymer
Particles, after its founder. Head loss decreased as
Lake Water passed through our filter, and then
increased rapidly when HCl was added. This proved
to us that a transparent substance existed in Cayuga
Lake water. A supernatant of Cayuga Lake water with
HCl was neutralized and we observed flocculation of
TEP, a yellow gelatin-like substance.
In order to prove the stickiness effect of TEP as
researched by Uta Passow (1994), we added TEP to
one slow sand filtration system and one without. An
E-coli stock solution was pumped through filter and
we compared the filtering effects of the two filter
systems. Effluent of both filters were collected and
tested for E-coli presence by growing them on agar
culture dishes. After two hours, the sand filter without
TEP produced an effluent of 0.84 E-coli colonies per
l of solution. The sand filter inundated with TEP
produced an effluent of 0.028 E-coli colonies per l of
solution, thirty times less E-coli colonies than the
control sand filter.
Introduction
Slow sand filters have been used to remove
particles from drinking water since the early 1800’s.
Although slow sand filtration is an old technology, the
mechanisms responsible for particle removal are not
well understood. Research conducted at Cornell
suggests that biofilms are not responsible for
significant particle removal and that most particles are
removed by physical-chemical mechanisms. In new
slow sand filters with clean filter media, particles are
initially removed by attaching to the filter media, thus
particles that are captured on slow sand filters have
been shown to significantly improve filter
performance (Weber-Shirk and Dick, 1997).
Improvement in filter performance with time is
referred to as “ripening” (Weber-Shirk, 2000).
Physical-Chemical filter ripening may be the result of
the changes in pore geometry that enhance straining or
the modification of filter media surfaces that enhance
the ability of particles to attach. Decreasing the pore
size to enhance straining is not an efficient way to
enhance filtration due to the decrease in head loss
(Weber-Shirk, 2000).
Transparent exopolymer particles (TEP) are
transparent particles that exist as discrete particles,
rather than as cell surface coatings. TEP are probably
generated abiotically from dissolved extracellular
polysaccharides, which diatoms excrete copiously.
The occurrence of these excretion products create
flocculation and aggregation effects (Passow, 2000).
Cayuga Lake water may contain such TEPs and this
report will address their existence and their
performance on slow sand filter systems.
Objectives
According to Professor Monroe Weber-Shirk of the
Environmental Engineering Department at Cornell
University, there seems to be a certain type of polymer
in Cayuga Lake water that promotes the stickiness of
filters, and thus enhances the performance of filters.
We, therefore, wanted to test this hypothesis.
From this laboratory experiment, first of all, we are
trying to prove if such a polymer exists in Cayuga
Lake water. If so, we are going to extract the polymer
from the lake water, and apply the polymer through a
slow sand filter in order to test the actual performance.
Materials
Testing Unknown polymer & Extraction
- Peristaltic pump (2)
- #16 pipes with plumbing connectors and angles
- #13 pipes with plumbing connectors and angles
- 20 liter HDPE Jerrican
- Cayuga Lake water from Boynton Point
- Distilled water
- Glass-fiber filter
- Compumet software to monitor pressure
- Pressure transducer
- 100 µL pipette
- 1000 µL pipette
Discovery and Application of Transparent Exopolymer Particles (TEP) in Cayuga Lake
1
Jung-Chae Park
Andrew (Dong Hyuk) Kim
5/15/2000
- 1N HCl solution
- 1N NaOH solution
- pH meter
- Magnetic stirrer
- High Speed Centrifuge
- Glass beads (420-297 µm in diameter)
- 2.5 cm filter column (2)
Membrane Filtration of E-Coli
-20 billion/liter E-coli stock solution
- 50 x 15mm culture dishes (15)
- Incubator at 35 degrees Celsius
- Filtration Unit consisting of seamless funnel fastened
to a base by a locking device
- Membrane filter with rated diameter for retention of
coliform bacteria
- Partial Vacuum system
- Sterile Dilution water
- Sterile Membrane 50mm filter
- Sterile Forceps
Methods
Testing the existence of the unknown polymer
We set up a system, which let water go through a
glass-fiber filter while monitoring the pressure on the
filter. We used #16 pipes for plumbing and ran the
water obtained from Cayuga Lake through the system
at the flow rate of 50 ml/min. When it showed a high
increase in pressure possibly due to the clogging effect
of the polymer, we injected 10 ml of 1N HCl in order
to test if it’s acid-dissolvable polymer that clogged up
the filter.
We then added 1N NaOH into the acid-dissolved
polymer solution that came through the system while
monitoring with a pH meter to obtain initial pH of
Cayuga Lake which was ~8.73. After neutralizing the
solution, we repeated the run again with the
neutralized polymer solution in order to make sure that
it really was the unknown polymer that clogged up the
filter. Lastly, we repeated the experiment once more
with distilled water, even adding 1N HCl and
contrasted the result with that of the polymer solution
test in order to be sure of the polymer’s existence.
Extraction
We obtained Cayuga Lake water with sediments,
and we added 1N HCl into the water in order to
dissolve all the polymers. After centrifuging them, we
obtained only the supernatant to get a more pure and
concentrated polymer solution.
Finally, we
neutralized the supernatant with 1N NaOH solution
and the pH meter and noticed flocculation and thus
observed physical evidence of TEP.
Slow Sand Filtration of E-Coli
We set up a system with two glass bead filters.
Each column consisted of 97.2 grams of glass beads to
fill the 73.63 ml of filter column. We used #13 pipes
for plumbing and set the flow rate of our pump to 1.65
ml/min. We poured 15 ml extracted polymer solution
into only one of the column filters. A reverse flow
procedure was used to inundate the glass beads with
water and to remove all air pockets that existed in the
filter columns. We then tested the performance of both
filters by pumping 20 billion per liter E-coli stock
through the system. Since the residence time of our
system was calculated as 18 minutes, we assumed
collecting effluent after 1 hour and 2 hour would give
us significant results. The type of samples collected is
displayed in Table 1.
Membrane Filtration Method
Using sterile forceps, we placed a sterile membrane
filter (grid side up) over a porous plate of receptacle.
Then placed a matching funnel unit over receptacle
and locked it in place. We added 10 ml of sterile
dilution water and added samples as specified in Table
1. We then filtered each sample under partial vacuum
and rinsed the interior surface of the funnel by filtering
three 20 l portions of sterile dilution water to avoid
carryover contamination. After we disengaged the
vacuum, we unlocked and removed funnel, then
immediately removed membrane filter with sterile
forceps, and placed it on agar plate by rolling motion
to avoid the entrapment of air. Then, we inverted the
dishes and incubated for 48 hours at 35  0.5 °C.
After 48 hours we removed filter from agar plate,
dried them and counted the colonies of coliforms
grown in each plate.
Results and Discussion
Testing Unknown polymer & Extraction
We tested the existence of the unknown polymer by
running the Lake water through the glass fiber filter.
Due to the unknown polymer’s clogging effect, the
pressure on the filter increased as we ran the water
through the system. Figure 1 indicates the increase in
pressure due to clogging.
2
60000
35000
50000
30000
Pressure (Pa)
Pressure (Pa)
Jung-Chae Park
Andrew (Dong Hyuk) Kim
5/15/2000
40000
30000
20000
10000
25000
20000
15000
10000
5000
0
0
0
100
200
Tim e (s)
300
400
0
50
100
150
Tim e (s)
200
250
Figure 1. Increase in Pressure with respect to time of
initial encounter with TEP due to clogging of filter.
Figure 3. Trial 2 of glass fiber filter of Cayuga Lake
water with addition of HCl to dissolve TEP.
As observed the head loss decreased since the
pressure difference across the filter increased rapidly,
thus announcing clogging of the glass fiber filter.
Then, we injected Hydrogen Chloride into the filter
to see if the clogging effect was in part due to TEP or
just the sediments of the Lake water. Figure 2 shows
the rapid decrease in pressure (increase in head loss)
after injection of HCl. The rapid decrease in pressure
showed that the acid dissolved the polymer. We
repeated the experiment with the neutralized polymer
solution (already filtered Lake water), and observed
similar results as shown in Figure 3.
Figure 4 shows the pressure vs. Time for distilled
water with addition of HCl. This was done to reassure
that the glass fiber filter, water, and HCl were not the
cause of the clogging effect and that TEP was solely
responsible for the increase in pressure. Figure 4
shows that the pressure is app. 3000 Pa, much lower
than that of the Lake water (Figures 1-3). It can be
also seen that there is neither rapid increase nor
decrease in pressure and the pressure level is relatively
constant. The slight increase in pressure is due to the
sudden injection of HCl into the filter.
4000
35000
3500
Pressure (Pa)
Pressure (Pa)
30000
25000
20000
15000
10000
3000
2500
2000
1500
1000
5000
500
0
0
0
50
100
150
Tim e (s)
200
250
Figure 2. Increase in Pressure then a rapid decrease in
pressure with respect to time after injection of HCl that
dissolved the TEP.
0
100
200
Tim e (s)
300
400
Figure 4. Pressure vs. Time of distilled water running
through the glass fiber filter. This system also contain
injection of HCl.
Since we know that the polymer is dissolvable by
acid, we extracted the TEP by titration. After adding
acid, we centrifuged the solution, and we later
neutralized it with base.
By this method, we
successfully extracted TEP, and observed flocculation
Discovery and Application of Transparent Exopolymer Particles (TEP) in Cayuga Lake
3
Jung-Chae Park
Andrew (Dong Hyuk) Kim
5/15/2000
of the yellow gelatinous-like substance, which we
discovered to be our TEP.
Membrane Filtration of E-Coli
To test the application of the newly discovered
polymer, TEP, and to test its stickiness characteristics,
we ran it through a slow sand filter. E-coli stock
solution of 3.45 colonies per l of solution was
pumped through the filter at 1.65 ml/min. The effluent
of filter system with TEP and a filter system without
TEP was collected after 2 hours. The effluent w/o
TEP (control 2hr) contained 0.863 colonies/l of
solution. The effluent with TEP inundated in the filter
(Polymer 2hr) contained 0.0284 colonies/l of
solution. Table 1 displays the different samples of
effluent collected and the number of colonies each
sample contained.
Bibliography
Passow, Uta; Alldredge, Alice L. 1995. “Aggregation
of a diatom bloom in a mesocosm: The role of
transparent exopolymer particles (TEP)” Deep Sea
Research II, 42: 99-109.
Weber Shirk, M., Lion, L.W. and Bisogni Jr., J.J.
2000. “Enhanced Slow Sand Filtration”
Laboratory
Research
in
Environmental
Engineering – Laboratory Manual, 4:105-109.
Weber-Shirk, M., and R. I. Dick. 1997. PhysicalChemical Mechanisms in Slow Sand Filters. Jour.
AWWA. 89:87-100.
Table 1. Sample volume of effluent collected from
agar culture plates with their respective number of Ecoli colonies grown in each sample.
Sample ID
Influent
Control 2 hr
Polymer 2 hr
concentration
sample
sample
sample
of E-coli
volume
volume
volume
(colonies/  l of
L
count
L
count
L
count
sol'n)
20
71
20
67
20
69
3.45
20
15
20
27
200
165
0.863
20
3
200
28
2000
32
0.0284
Conclusion
Professor Monroe Weber-Shirk’s hypothesis on the
existence of transparent polymers that enhance slow
sand filtration was true. The clogging effect of the
glass fiber filter of Cayuga Lake water and the
unclogging after HCl was added proved that such a
substance does exist, and thus respectively named it
Transparent Exopolymer Particle (TEP).
The
existence of this polymer was further evident after
titrating diluted centrifuged Supernatant Lake water.
A yellow gelatinous-like polymer flocculated out of
nowhere and thus proved that TEP was no longer a
myth.
Running it through a slow sand filtration finally
tested the application of TEP. E-coli was used as a
filtrant and effluent of filter with TEP showed thirty
times less E-coli colonies compared to the control
filter without TEP, thus proving that TEP enhanced the
slow sand filter system. Although the results showed
significant proof, one more run of the slow sand filter
may have solidified the proof that TEP can definitely
enhance slow sand filtration. However there is no
doubt that TEP exists in Cayuga Lake water.
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