Effectiveness of Advanced Nitrogen-Removal Onsite Wastewater Treatment Systems in a New England Coastal Community
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Effectiveness of Advanced Nitrogen-Removal Onsite Wastewater Treatment Systems in a New England Coastal Community Bianca N. Ross & Kevin P. Hoyt & George W. Loomis & Jose A. Amador
Received: 12 June 2020 / Accepted: 26 October 2020 # Springer Nature Switzerland AG 2020
Abstract Wastewater is a major source of nitrogen (N) to groundwater and coastal waterbodies, threatening both environmental and public health. Advanced Nremoval onsite wastewater treatment systems (OWTS) are used to reduce effluent N concentration; however, few studies have assessed their effectiveness. We evaluated the total N (TN) concentration of effluent from 50 advanced N-removal OWTS in Charlestown, Rhode Island, USA for 3 years. We quantified differences in effectiveness as a function of N-removal technology and home occupancy pattern (seasonal vs. year-round use), and examined the relationship between wastewater properties and TN concentration. RX30 systems produced the lowest median TN concentration (mg N/L) Supplementary Information The online version contains supplementary material available at https://doi.org/10.1007 /s11270-020-04911-5. B. N. Ross (*) : K. P. Hoyt : J. A. Amador Laboratory of Soil Ecology and Microbiology, University of Rhode Island, 1 Greenhouse Rd., Kingston, RI 02881, USA e-mail: [email protected]
K. P. Hoyt e-mail: [email protected] J. A. Amador e-mail: [email protected] G. W. Loomis New England Onsite Wastewater Training Center, University of Rhode Island, 102 Coastal Institute, 1 Greenhouse Rd., Kingston, RI 02881, USA e-mail: [email protected]
(13.2), followed by FAST (13.4), AX20 (14.9), and Norweco (33.8). Compliance with the state’s regulatory standard for effluent TN concentration (19 mg N/L) was highest for RX30 systems (78%), followed by AX20 (73%), FAST (67%), and Norweco (0%). Occupancy pattern did not affect effluent TN concentration. Variation in TN concentration was driven by ammonium and nitrate for all technologies, and also by temperature for FAST and pH for Norweco. Median daily (g N/day) and annual (kg N/yr) N loads were significantly higher for year-round (5.3 and 2.3) than for seasonal (3.7 and 0.41) systems, likely due to differences in volume of wastewater treated. Our results suggest that advanced Nremoval OWTS vary in their compliance with the state regulatory standard for effluent TN and can withstand long periods of non-use without compromising effectiveness. Nevertheless, systems used year-round do produce a higher daily and annual N load than seasonallyused systems. Keywords Onsite wastewater treatment systems . Wastewater . Nitrogen . Biological nitrogen removal
1 Introduction Effluent from onsite wastewater treatment systems (OWTS) is an important source of nitrogen (N) to coastal watersheds (Valiela et al. 2010). Because N is a limiting nutrient in coastal ecosystems, increased inputs of N to groundwater and poorly flushed coastal systems promote eutrophication, which results in anoxia that
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kills fish and shellfish. Eutrophication can also boost the growth of t
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