Enhanced onsite wastewater treatment for significant nitrogen removal: a neighborhood-scale demonstration study in Barnstable, MA (Cape Cod)
Citation:
Erban, L., S. Wigginton, E. Olmsted, B. Horsley, T. Gleason, AND B. Baumgaertel. Enhanced onsite wastewater treatment for significant nitrogen removal: a neighborhood-scale demonstration study in Barnstable, MA (Cape Cod). NEWEA Spring Meeting 2024, Newport, RI, May 19 - 22, 2024.
Impact/Purpose:
Nitrogen in onsite wastewater effluent is a concern in watersheds throughout country and particularly in the Northeast. The New England Water Environment Association (NEWEA) is a group of more than 2,000 water and wastewater professionals with a task force dedicated to Innovative and Alternative (I/A) onsite wastewater treatment systems (OWTS). This presentation will discuss current performance results and operational lessons learned from a field demonstration underway in Massachusetts of I/A OWTS designed for enhanced removal of nitrogen in effluent. The audience is uniquely suited to receive the findings and respond with future directions for research and implementation.
Description:
Onsite wastewater treatment systems are a major source of excess nutrients and co-pollutants in groundwater. The high density of septic systems in New England’s coastal watersheds has degraded the quality of drinking and recreational freshwater resources and led to collapse of estuarine ecosystems. The estuarine Total Maximum Daily Loads (TMDLs) for nitrogen (N) for more than half of watersheds in Cape Cod, Massachusetts, are prompting sewer expansion, wastewater treatment plant upgrades, and complementary interventions to reduce N loading. Enhanced Innovative and Alternative (I/A) septic systems that incorporate a lignocellulosic carbon source to augment denitrification can remove most N from influent and have the potential to exceed a recently established state regulatory goal of 10 mg/L TN for best available N-reducing technologies (310 CMR 15.002). The field performance of carbon-based technologies installed at 14 neighboring homes in Barnstable, MA, is being evaluated by EPA’s Office of Research and Development and the Massachusetts Alternative Septic System Test Center, in partnership with the Barnstable Clean Water Coalition. More than a year of high-frequency sampling for nutrients (N, P), ancillary water quality parameters and flow show it is possible to achieve >90% reduction in N concentrations and total loads and reliably exceed the new performance goal. This cohort currently shows long-run mean effluent TN of 9.8 mg/L (median: 3.2 mg/L) when used as designed. In-progress results will be discussed in the context of operations, monitoring and maintenance. Findings support consideration of where and how enhanced I/A septic systems can contribute to water quality goals in vulnerable watersheds.
