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Scattered thunderstorms developing late. Low 66F. Winds NE at 5 to 10 mph. Chance of rain 40%.
"Raw sludge" and "digested sludge" are pumped through pipes through a dewatering machine.
Ducks sit on the arm of a clarifier tank at the West Lafayette wastewater treatment plant.
This bacterial tank was emptied while students were gone for the summer. Bacteria is used to eat pollutants such as phosphorous.
Effluent wastewater flows through tanks. Solids are filtered out when they sink to the bottom.
"Raw sludge" and "digested sludge" are pumped through pipes through a dewatering machine.
Ducks sit on the arm of a clarifier tank at the West Lafayette wastewater treatment plant.
This bacterial tank was emptied while students were gone for the summer. Bacteria is used to eat pollutants such as phosphorous.
Effluent wastewater flows through tanks. Solids are filtered out when they sink to the bottom.
A family of ducks floated in a sparkling water clarifier, one of the final tanks in the path of wastewater from West Lafayette into the Wabash river. They waddled obliviously across the mechanical arm that skims “solids” off the water’s surface after climbing onto it from the water.
About 30 feet below them, heavier solids settled at the bottom of the tank.
The tank is one of many in West Lafayette’s water treatment plant that is tested for pollutants and diseases such as COVID-19 during the process. Water shipped to and tested by a third-party company has shown an increase in cases over the last several months.
To ensure the treated wastewater meets the Environmental Protection Agency’s standards of cleanliness, it is tested at multiple points in the process for phosphorus, ammonia and nitrogen, pollutants which cause oxygen-leeching bacterial growths.
The wastewater’s pH is tested to ensure neutrality. The presence of E. coli, an indicator of the presence of other pathogens, is tested using a process called fluorescence analysis.
While most of the testing takes place in the plant’s on-site laboratory, the plant uses a third-party company called BioBot to conduct its COVID tests. Neither the EPA nor anyone else sets parameters for COVID levels.
The plant began testing for it in 2020 so Tippecanoe County could have a better understanding of the pandemic in the area.
David Henderson, the plant’s administrator, said BioBot reached out to the plant to offer testing services as part of its goal to test for COVID in as much of the U.S. population as possible.
While the West Lafayette Wastewater Treatment Plant is treating wastewater, BioBot is testing samples for COVID from plants from around the country. Last summer, it provided COVID data to 30% of the U.S. population, BioBot representative Nour Sharana said.
Tippecanoe County has four wastewater treatment plants, but the West Lafayette plant is the only one that sends samples to BioBot, which uses the West Lafayette plant data to represent COVID data for the entire county.
BioBot is the only wastewater testing company contracted by the Centers for Disease Control and Prevention. It reports all results to the CDC.
BioBot uses a process called quantitative polymerase chain reaction to test their samples. Wastewater kills COVID, leaving pieces of its RNA behind. Q-PCR effectively tests for the presence of COVID RNA.
The most common COVID tests are antigen tests. They test for the presence of COVID antibodies which activate a dye, or the line one sees on a positive take-home COVID test.
Antigen tests are cheaply mass produced but can produce false negatives because a subject must have enough antibodies to activate the test. Early in infection, there may not be enough antibodies to produce an accurate result.
Q-PCR testing, on the other hand, requires specialist equipment and can be expensive, but it can detect extremely small quantities of virus. In a Q-PCR test, a small piece of RNA called a “primer” is manufactured to match a segment of COVID RNA.
The sample, including the primer, is combined with a synthetase enzyme and nucleotides, the “builders” and “building blocks” of DNA, respectively. This allows a strand of COVID DNA to be produced. The DNA is split when heated, creating two copies of RNA.
This process is repeated until thousands of copies of COVID DNA exist in the sample. Based on how many are produced, scientists can determine how many copies of RNA were in the original sample.
BioBot genetically maps their samples so it knows which strain of COVID is present. While these results can’t tell testers how many infected individuals are in the community, they can demonstrate whether infections are increasing in number over time.
Tice said this technology gives us the capacity to look for a pandemic before it happens, citing the discovery of polio in a New York county’s wastewater earlier this month. BioBot doesn’t test for diseases other than COVID, but Sharana said the company is researching and developing rapid-result testing for influenza.
While Sharana said BioBot receives samples from over 350 communities in all 50 states, Michael Pollak, an associate professor of economics at Indiana University Northwest, said the company is only able to look at highly populated areas.
“All communities need wastewater testing,” Sharana said. “Even if one community has more disease than another, they all still need testing.”
There are significant differences between the reports sent to plants and the reports BioBot posts on their website. Pollak described their website data as “smoothed,” showing averaged spikes and dips over time instead of virus quantities that regularly fluctuate by hundreds of thousands of copies with every report.
Pollak said their data-smoothing process is “blackboxed” and not available to the public.
Sharana said there is an “undercounting” in official COVID numbers. While hospitals, clinics, labs and states have data-sharing agreements, official COVID testing has reduced as the virus has become less severe with higher vaccination rates.
Pollak said Indiana requires hospitals to share COVID test results, but the state voluntarily reports these results to the CDC.
Greg Loomis, officer of the Tippecanoe County Department of Health, said his department reports numbers of communicable diseases to Indiana Disease Intervention Specialists each year. If there is an outbreak of a disease such as rabies or tuberculosis, they report directly to the CDC.
He said his department immediately reports cases of monkeypox to the DIS.
“A lot of data has to be gathered for epidemiology in reportable cases,” Loomis said. “You have to report case numbers that are out of the ordinary.”
Long before the wastewater treatment plant was testing the water for COVID, it was treating the water.
West Lafayette’s Wastewater Treatment Plant processes 6.13 million gallons of sewage a day. Purdue and West Lafayette have individual pipes of “raw sludge” or “influent” that combine in the plant’s “influent tank.”
“Purdue is its own city,” Steve Tice, the plant’s laboratory manager, said. “We have to shut down an entire tank when school is out.”
Once the wastewater leaves the influent tank, it is pumped through about 15 sets of tanks that remove pollutants using gravity filtration, anaerobic bacteria cleaning, and chlorination. The clean water is pumped into the Wabash River.
“We remove 95% of pollutants, which includes total suspended solids and biochemical oxygen demands, or pollution in the water that could take oxygen away from the fish,” Tice said. “We make sure that we are not putting in pathogens or disease-causing organisms into the wild.”
Less than 1% of influent is pollutants, which means only 0.05% of the water released back into the river contains pollutants. Influent is everything that enters the wastewater treatment plant after being flushed. While it may not be entirely safe to drink, it won’t spread diseases or harm plant and animal life.
Tice collects wastewater samples once a day and mails them to BioBot every three days for testing.
The samples are collected from the “effluent” segment of the plant, the segment where most of the solids, including sand, dirt and anything that gets flushed down toilets, are removed. An automatic sampler fills four large bottles with wastewater over a 48-hour period.
“It sucks out the water on a timer by itself,” Tice said as he pulled the bottles out of the sampler. “It makes it so we can collect it just once a day.”
The sampler is located outdoors beside a deep effluent tank with a maintenance bridge above it. Nearby is a dumpster filled with blackened sand that has been filtered from the wastewater.
Tice removes the bottles from the sampler and pours them into one container to create a “composite” sample. The effluent wastewater is pale green and cloudy.
The excess from Tice’s sample is poured down the drain in a nearby building that is home to a dumpster full of solid waste.
Once the samples are collected, Tice takes them to the lab where they are refrigerated until three days of samples are collected.
Earlier this month, Tice was training the laboratory technician, Chris Speers, 38, to process the samples destined for BioBot.
Speers filled three vials, each representing one day of sampling, with 50 milliliters of wastewater. Then he places the samples in a pool of ice in a FedEx package addressed to the BioBot lab in Cambridge, Massachusetts, and logs them using the BioBot app.
BioBot releases the results of the test in two days, posting a summarized version on their website and sending the plant a detailed report.
Although the plant does not report COVID levels to the EPA or the Indiana Department of Environmental Management, they send the IDM a monthly pollutant report. Tice said their pollutant levels, particularly those of E. coli, are “very low.”
To test E. coli levels, effluent water is placed in a plastic package with a square of plastic bubbles. The package is placed under an ultraviolet light. Bubbles with high E. coli levels “phosphoresce,” or glow blue.
The E. coli level is calculated based on the ratio of phosphorescing bubbles to dark ones. The IDM requires E. coli scores to be lower than 235. If the level ever goes over the requirement, the plant has less than a day to report the result to the IDM.
Tice said he has never seen this happen, the plant usually has a score of 5 or less.
Tice said the wastewater treatment plant has been continuously expanded since it was originally built in the mid-1900s.
In the 1800s, Tice said common diseases such as cholera and typhoid were spread through untreated sewage poured into rivers. He said in the 1940s, people in canoes on the Wabash River had to steer around “islands of sewage.”
The plant’s first treatment tank was built to filter solids out of the wastewater, but it was the only tank in the plant until the Clean Water Act was passed in 1972.
The Clean Water Act established federal regulations surrounding water pollutants. The plant continued to expand in the direction water flowed out of West Lafayette until its infrastructure spread over an uphill slope.
The water is kept flowing by massive underground pumps. If the plant loses power, and its backup generator fails, the pumps will stop working, and the plant will flood with sewage.
Tice said most wastewater treatment is accomplished by gravity. Solids sink to the bottom of tanks called clarifiers.
The leftover solids don’t go to waste. A portion of the sludge is pumped into a machine that removes any excess water.
The dry sludge is then burned to produce electricity for the plant. Tice said this saves the plant about $60,000 a year.
The rest of the sludge is saved to use as crop fertilizer.
Ammonia, phosphorus and nitrogen are removed using anaerobic bacteria. The bacterial tank is filled with brown, bubbling sludge, which is kept supplied with amoebas, rotifers, ciliates and other kinds of bacteria that consume pollutants.
Tice said the wastewater is cycled through the bacterial tank multiple times to keep the massive bacteria culture alive and remove as many pollutants as possible.
After leaving the bacterial tank, the water flows through a chlorine contact system which kills microorganisms. The chlorine is removed with sodium bisulphate. At this point in the process, the flowing water is sparkling clear and ready to be sent to the Wabash.
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