Erban Laura E, Wigginton Sara K, Baumgaertel Brian, Horsley Bryan, McCobb Timothy D, Crocker Zenas, Horsley Scott, Gleason Timothy R
U.S. Environmental Protection Agency, Office of Research and Development, Narragansett, RI, USA.
Massachusetts Alternative Septic System Test Center, Sandwich, MA, USA.
J Environ Manage. 2024 Nov;370:122737. doi: 10.1016/j.jenvman.2024.122737. Epub 2024 Oct 11.
Onsite wastewater treatment systems (OWTS) are a major source of excess nutrients and co-pollutants in watersheds across the United States. In Barnstable County (Cape Cod), Massachusetts, effluent from septic systems and cesspools contributes approximately 80% of the controllable reactive nitrogen (N) load to numerous impaired estuaries and degrades water quality in the region's sole source aquifer, streams and ponds. In unsewered areas, wastewater N loads could be reduced substantially by Innovative/Alternative (I/A) septic systems designed for enhanced removal. Use, however, has been partly limited by the availability of high performing, cost effective options, while conventional septic systems continue to be installed in watersheds with well documented N impairments. This paper describes the strategic replacement of residential OWTS with two I/A models that incorporate woodchip bioreactors to enhance N removal. Systems were installed at 14 neighboring homes in Barnstable, MA, and monitored for field performance. Influent and effluent were sampled monthly and analyzed for N and phosphorus (P), among other water quality indicators. Flow to each system was continuously metered to estimate nutrient loads. Results from the first 25 months of monitoring for 13 systems with at least a full year of data are presented in terms of 1) reductions in nutrient concentrations and mass loads and 2) reliability of the systems for meeting a performance goal of total N (TN) < 10 mg/L. Discussion supports consideration of where and how these technologies may be successfully used to manage excess N in sensitive watersheds.
现场污水处理系统（OWTS）是美国各地流域中过量营养物质和共污染物的主要来源。在马萨诸塞州的巴恩斯特布尔县（科德角），化粪池系统和污水池的废水对众多受损河口的可控活性氮（N）负荷贡献约80%，并使该地区唯一的水源含水层、溪流和池塘的水质恶化。在没有下水道的地区，通过设计用于强化去除的创新/替代（I/A）化粪池系统，可以大幅减少废水的氮负荷。然而，其应用部分受到高性能、高性价比选项可用性的限制，而传统化粪池系统仍继续安装在氮污染记录完备的流域。本文描述了用两种采用木屑生物反应器以强化氮去除的I/A模型对住宅OWTS进行的战略性替换。这些系统安装在马萨诸塞州巴恩斯特布尔的14户相邻住宅中，并对其现场性能进行监测。每月采集进水和出水样本，分析其中的氮和磷（P）以及其他水质指标。持续计量每个系统的流量以估算营养负荷。对13个至少有一整年数据的系统进行的前25个月监测结果，从以下两方面呈现：1）营养物浓度和质量负荷的降低；2）系统达到总氮（TN）<10mg/L性能目标的可靠性。讨论支持考虑在何处以及如何成功应用这些技术来管理敏感流域中的过量氮。
