2. E. Coli in North Creek
We have certainly been over this before.
Fecal Coliform levels in North Creek are
way, way above federal and safe limits., it
was placed on 303(d) list in 1996. State
water quality standards require mean
bacteria counts of 50cfu/100mL not
exceeding 100cfu/100ml. Non point
sources of pollution include: contaminated
soil from the former pasture, stormwater
runoff during rain events, and the large
crow population.
3. Battling the Feces
-The North Creek Wetlands was created to act as a filter for
stormwater runoff from downtown Bothell and its urban watershed
and drains approximately 30 square miles and discharges to the
Sammamish River, which is tributary to Lake Washington.
-Data shows E.Coli levels are way above public health standards
-Has multiple waterways contaminated with Fecal Coliform, but a
big source is from SW2
-Local government programs include: water quality monitoring,
education and outreach to raise awareness
SW 3 after a heavy rain event. (photo credit David Jackson, 2016)
4. Enter the Shroom
- Mycelium is the root structure of fungi. Mycoremediation utilizes fungi to reduce
contaminants in water.
- The mycelium secrete digestive enzymes that have been shown to break down a wide
variety of toxic molecules into simpler components.
-“Waddles” are being constructed from different materials that biodegrade
and inoculated with mycelium, then wrapped in burlap.
-The waddles are then planned to be placed across contaminated streams and is slowly
filtered as it enters one end. So in theory, “clean” water is discharged through the other end.
-By using a box filter filled with mycelium, samples of controlled and contaminated water
were filtered through the mycelium and the filtered water would hopefully show a reduction
in E.Coli
5. The Mighty Box Filter
The top section was perforated, to allow our raw
samples to drain through. It has to be sterilized
after each use.
The second section is filled with mycelium
(Oyster Pearl) and a substrate. This is also
perforated to allow water to pass.
The third is empty to catch the water that has
passed through the filtering mycelium. It has tic
marks showing water levels so we can measure
residency time.
Raw Water
Mycelium
Filtered Water
6. Round One!
We used water gathered from North Creek near SW4. We took about 8 gallons
out to ensure we would have enough.
We sampled from the raw stream water, weighed the mycelium, and then
poured 4,000 mL (just over 1 gallon) into the box filter.
It took a little over a minute for most of the water to drain. (1:18 second for
~3750mL).
We took samples from the filtered water, and from the water that dripped out
more slowly, and set all of them to culture.
7. If at First You Fail...
As you can see, we the results were
not what we hypothesized.
E. Coli increased in both samples
after it had been run through the
mycelium. In the drip, the other
coliform counts were higher than
ever.
8. What Went Wrong
Immediately we came up with several ideas:
- Maybe the mycelium or substrate was
loaded, we should have run distilled water
through first and tested it.
- Maybe the residency time was too low.
- Maybe the sample we used wasn’t
sufficiently contaminated with E. Coli.
9. Round Two!
We decided to address two problems at once.
- We would run another test, but start with distilled water to ensure that we had
no contamination in the mycelium itself. If the distilled water (di water in our
notes) came back contaminated, then we would know why our numbers were
off.
- Secondly, we decided to take a smaller sample, only about 3 gallons, from
directly in SW4 to ensure we had the same, high contamination rate we were
missing with the previous sample. It would still leave us with enough to run
the box filter experiment and get plenty of samples for culturing.
- We took our raw samples, weighed the mycelium, put the distilled water
through (2000mL this time), and took the filtered samples.
- We then weighed the mycelium again, put our pond water through (2000mL),
weighed the mycelium one last time, and took samples from the filtered water.
10. The Un-Amazing Discovery
The distilled water showed us
nothing. Neither the mycelium nor
substrate were not loaded with fecal
coliform.
However, it also did not show us a
any remediation of the fecal
coliform counts.
The issues we tried to control for
weren’t the problem after all.
11. Pearl vs. King: The Hypothesizing
The graph to the right shows the percentage of E. coli that
was remediated by a “runthrough” similar to ours. This
runthrough, however, used King Stropharia.
Note that the reduction was significant, where our
runthrough with Pearl Oyster was not.
This leads us to believe that Oyster Pearl requires greater
residency time than King Stropharia to clean Fecal
Coliform.
12. Citations
1. Turner, R (2016). Personal communication. BES 318 course lecture.
2. Revised Total Coliform Rule And Total Coliform Rule. Federal Register (FR) on February 13, 2013
(78 FR 10269). Available from: https://www.epa.gov/dwreginfo/revised-total-coliform-rule-and-
total-coliform-rule#rule-summary
3. Malloney K. 2016. Mycoremediation project outline, spring. UWB.
4. Malloney K. 2016. E. Coli Analysis. UWB.
5. Ralph Svrjcek. 2003. North Creek Fecal Coliform Bacteria Total Maximum Daily Load:
Washginton State Department of Ecology; 03-10-047.
