Mesocosm- and Field-Scale Evaluation of Lignocellulose- Amended Soil Treatment Areas for Removal of Nitrogen from Wastewater

Sara Wigginton,George Loomis,George Heufelder,Brian Baumgaertel,Jose Amador

doi:10.3390/w13152137

Sara Wigginton, George Loomis + Show 3 more

Open Access

https://doi.org/10.3390/w13152137

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Abstract

Non-proprietary N-removal onsite wastewater treatment systems are less costly than proprietary systems, increasing the likelihood of adoption to lower N inputs to receiving waters. We assessed the capacity of non-proprietary lignocellulose-amended soil treatment areas (LCSTAs)—a 45-cm-deep layer of sand above a 45-cm-deep layer of sand and sawdust—to lower the concentration of total N (TN) in septic tank effluent (STE) at mesocosm and field scales. The mesocosm received wastewater for two years and had a median effluent TN concentration of 3.1 mg/L and TN removal of 60–100%, meeting regulatory standards of 19 mg/L or 50% removal. Removal varied inversely with temperature, and was lower below 10 °C. Removal was higher in the mesocosm than in five field sites monitored for 12–42 months. Median effluent TN concentration and removal met the standard in three continuously-occupied homes but not for two seasonally-occupied homes. Sites differed in temporal pattern of TN removal, and in four of five sites TN removal was greater—and effluent TN concentration lower—in the LCSTA than in a control STA containing only sand. The performance of non-proprietary LCSTAs was comparable to that for proprietary systems, suggesting that these may be a viable, more affordable alternative for lowering N inputs to receiving waters.

Highlights

Coastal communities often rely on onsite wastewater treatment systems (OWTS; known as septic systems) to treat residential wastewater
Because temperature affects total N (TN) removal in lignocellulose-amended soil treatment areas (LCSTAs) [13,14,15] (Figure 3), we examined climatic differences between Barnstable and Suffolk County as an explanation for difference in performance
Data from mesocosm–scale testing suggests that the soil treatment area (STA) design we evaluated is highly effective for N removal

Summary

Introduction

Coastal communities often rely on onsite wastewater treatment systems (OWTS; known as septic systems) to treat residential wastewater. Nitrogen pollution in coastal waters can lead to eutrophication, hypoxia, the death of fish and benthic communities [2], and harmful algal blooms [3]. Proprietary, commercially–available advanced OWTS are designed for improved removal of target contaminants associated with conventional OWTS They are used in areas sensitive to contamination of surface and ground water with pathogens, excess organic carbon (C), and/or nitrogen. The latter, referred to as N–removal OWTS, rely on sequential processes similar to those of a wastewater treatment plant with biological N removal (BNR)

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