Skimmer Could Reduce Toxic Algae And Nitrogen Pollution In Lake Agawam

The international engineering firm that conducted an algae-skimming pilot program at Southampton Village’s ailing Lake Agawam in 2019 presented the results to the Village Board last month and explained how the technology could be used to remove not only toxic blue-green algae from the lake but nitrogen and phosphorus pollution as well.

According to representatives of AECOM, harmful algae blooms are increasing in intensity, lasting longer and becoming more toxic due to climate change, but algae-skimming technology can mitigate the crisis. Daniel Levy, an AECOM vice president specializing in environmental consulting, said Lake Agawam could have “very clear water” within two to three years if an algae harvester is run 180 days per year.

That would mean much faster results than other measures the village is taking, principally creating a sewage district and building a sewage treatment plant.

“The AECOM algal skimmer will have an immediate impact by not only removing some of the toxic algae and microcystin, but it actually removes some of the nutrients from the water, including nitrogen and phosphorus, and those nutrients are what cause the toxic algal blooms,” Mayor Jesse Warren said during the September 18 presentation.

The mayor noted that while the village plans to have its sewer district map and plan complete by the end of the first quarter of 2022, the village is still five to seven years out from fulfilling its infrastructure goals. He added there is also a “legacy load” of nitrogen in the watershed area that could take at least 10 years to move through.

AECOM has been working with the Army Corps of Engineers, the federal Environmental Protection Agency, the federal Department of Energy and agencies in Florida to develop a technology that can be used nationally to address the growing crisis of toxic algae blooms, Mr. Levy said. He explained that the technology that was piloted in Lake Agawam uses a flotation process to separate water from algae. “It creates a slurry, then we can take the slurry out — physically separate that from the water column,” he said.

The process takes out billions of algae cells rapidly, is cost effective and scalable, and can be implemented throughout the nation, according to Mr. Levy, who noted that the removed algae can be used to make jet fuel and fertilizer. It can also be used to make “bio foam” for sneakers, he added.

The pilot took place over 10 consecutive days in October 2019. “During that time of the 10-day test, Lake Agawam, for us, gave us a key point in our research because the lake itself had a consistent level of microcystin,” Mr. Levy said, referring to the toxin produced by blue-green algae.

During 59 hours of operation during the pilot period, the system treated 257,000 gallons of water — just 0.1 percent of the lake volume — and two samples were taken each day.

“What we showed is that we can take out the nitrogen, the phosphorus, the cyanotoxins and the carbon at Lake Agawam in a very effective way, and we can do it rapidly and we can do it in a system that’s scalable,” Mr. Levy said.

Algae is 106 parts carbon, 16 parts nitrogen and 1 part phosphorous, he said. “The algae is doing the homework for us. The algae is picking up the nitrogen, the phosphorus, the carbon. That’s a wonderful thing.”

He also noted that the algal harvester treats water at the surface of the lake because that is where algae accumulate in high concentrations during the day to get sunlight. A series of pumps would be installed around Lake Agawam rather than one high-volume pump.

While a lake for recreational use should have no more than 1,200 parts per billion, or ppb, of nitrogen, Lake Agawam contains 3,460 parts per billion of nitrogen, according to AECOM. The tests showed that treated water contained just 620 ppb of nitrogen. Likewise, phosphorus content was reduced from 220 ppb to 10 ppb, when the goal was 40 ppb or less.

Tammy Karst-Riddoch, a senior aquatic scientist at AECOM, noted that Dr. Chris Gobler of the School of Marine and Atmospheric Sciences of Stony Brook University has found that nitrogen loading into Lake Agawam is 11,542 kilograms per year. It comes from a number of sources, but the biggest contributor is wastewater.

According to AECOM’s presentation, a sewage treatment plant will reduce nitrogen loading by 30 percent. Meanwhile, an algae-skimming system operating at 2 million gallons a day for 180 days would remove 40 percent of the annual nitrogen load. A 3-million-gallon system would achieve 60 percent removal.

For phosphorus, a 2-million-gallon system would remove 27 percent of the annual phosphorus load, and a 3-million-gallon system would remove 41 percent.

For toxins, namely, microcystins and nodularins, Lake Agawam averaged 40 ppb during the 20 tests over 10 days. One test found only 8 ppb, while the highest result was 170 ppb. The goal for EPA recreational guidelines is 8 ppb, and the treatment system got toxins below 2 ppb by day four. Mr. Levy said that further treatment using ozone got the microcystin levels to less than 0.3 ppb, which is the standard for drinking water.

“This Lake Agawam research has really moved the bar on what could be done on toxic algae,” Mr. Levy said.

To drive home the point of why microcystin removal is imperative, he pointed out that microcystin can stay in the air for up to four hours and has been found in the nasal passages of people up to 10 miles away from the water where it originated.

According to the EPA, symptoms of exposure to microcystins include abdominal pain, headache, sore throat, vomiting and nausea, dry cough, diarrhea, blistering around the mouth, and pneumonia.

Mr. Levy said that the cost of AECOM’s first algae harvester was $1 million, though he did not provide a quote for how much one would cost for Lake Agawam specifically. How many years the system would be needed for would depend on continued nitrogen loading, he said. He pointed out that if a hurricane stirred up sediments in the lake, that would increase loading.

Mr. Warren showed interest in purchasing a harvester and said that it could be moved to Old Town Pond in the future after treating Lake Agawam, and could someday be rented to Southampton Town for a return on the village’s investment.