On Wednesday, February 24, Civil and Environmental Engineering Professor David Reckhow was one of four speakers invited to participate in a forum on Cape Cod wastewater treatment and contaminants. Professor Reckhow is one of the country’s leading researchers in this field. The forum was attended by 70 people at the Unitarian Universalist Fellowship in East Falmouth and was entitled “Wastewater and Emerging Toxic Contaminants of Concern,” sponsored by Cape Cod & the Islands Group – Sierra Club, the Silent Spring Institute, and the Green Sanctuary Committee.
The meeting was designed to initiate a dialog on how to address emerging contaminants, such as personal care products, endocrine disruptors, pharmaceuticals, and household cleaning products associated with wastewater.
The discussion focused on detection of some of these chemicals in our surface and ground water on Cape Cod, as well as potential treatment options as the wastewater infrastructure is upgraded.
A groundbreaking study by the U.S. Geological Survey in 2002, and another published by the Associated Press in 2008, found significant concentrations of pharmaceuticals and other chemicals in drinking water across the country. Other compounds topping the list were DEET, the main ingredient in bug spray; caffeine; flame retardant; and an active ingredient found in soaps, fertilizers, and detergents.
A report published on the Capenews.net website, maintained by The Enterprise newspaper group of Cape Cod, included the following coverage of Professor Reckhow’s remarks:
Greater understanding of the issues posed by endocrine disruptors in drinking water will lead to better wastewater treatment planning, said Professor Reckhow.
“If we knew which [chemicals] were most important to remove, that would make our lives a lot easier. We’d know which treatment method to pick,” he said.
Some treatment processes work better than others at breaking down the compounds, reverting them to harmless carbon dioxide and water, he said. “Large treatment plants tend to be more successful at removal. It seems that, the older the bacteria, the more effective they are. Just like us, the older you are, the better you get,” he said, eliciting laughter from around the room.
Bacteria are an essential process in wastewater treatment, and are recycled as biomass at the end of the treatment cycle. “Recycling allows them to become more diverse and biodegrade a greater range of compounds,” Dr. Reckhow said. In studies, 5-day-old bacteria were able to break down chemicals found in sunscreen. More complex chemicals, such as galaxolide, a component of fragrances, required bacteria over 15 days old to biodegrade.
The researchers also found that ultraviolet light, often used to disinfect wastewater at the tertiary treatment stage, is able to destroy the chemicals that escaped biological breakdown.
Dr. Reckhow outlined the benefits of various advanced treatment methods, analyzed in a recent study of wastewater in the Puget Sound area. There are four levels that are able to break down increasing numbers of chemical compounds. The most advanced system includes, after secondary treatment, coagulation and filtration, bionutrient removal and membrane filtration, and chemical coagulation.
Due to the combination of both aerobic and anaerobic breakdown processes, as well as chlorine treatment, close to 100 percent of the chemicals were removed from the wastewater stream, Dr. Reckhow said. However, they were found concentrated in the sludge, a byproduct of wastewater treatment that is usually disposed of by incineration.
Gerald C. Potamis, the Falmouth wastewater superintendent, asked the speakers if they thought treatment for total organic carbon (TOC) is an appropriate surrogate for capturing endocrine disruptors and other contaminants. In Falmouth, the wastewater treatment facility treats water to a standard of three TOC per liter.
Dr. Reckhow said that using the TOC standard is “a blunt tool” for removing potentially harmful compounds. Carbon comes from a variety of natural sources, including tree leaves, he said. In some places, boron is used as a tracer for pharmaceuticals, making them easier to identify. However, using boron would be problematic on the Cape, where most of the disposed wastewater winds up eventually in the ocean. Dr. Schraider added that even if the TOC content is reduced, it would not necessarily remove all the chemicals.
Jonathan R. Todd, president of John Todd Ecological Design in Woods Hole, asked if decentralized wastewater treatment plants could be just as effective in removing nutrients and chemicals. “If we could more rapidly deploy decentralized systems, wouldn’t it make just as much sense [as a central facility], and be much cheaper?” he asked.
Dr. Reckhow said he thinks decentralized systems have a lot of merit, but they require constant monitoring. One benefit, he said, is that the discharge would also not be centralized, resulting in lower concentrations of contaminants.
Mr. Todd pointed out that there could be natural attenuation in the soil as well, to which a member of the audience asked if that possibility has been studied. George R. Heufelder, director of the Barnstable County Department of Health and Environment, said that he is about to begin a study of the chemical breakdown of wastewater through soil and air dispersal systems.
A woman in the audience asked if her Brita water filter would be able to remove endocrine disruptors from her tap water. Dr. Reckhow said that the charcoal filter could be very effective, provided that it is new. As the filter ages, he said, it could actually release the concentrated contaminants right into the glass.
State Representative Matthew C. Patrick (D-Falmouth) asked if boiling water would work, to which Dr. Reckhow responded with a negative.