Mechanisms of Ammonium Transformation and Loss in Intermittently Aerated Leachfield Soil

Richard, John T.; Potts, David A.; Amador, José A.

doi:10.2134/jeq2014.02.0046

Cited by 9 publications

(7 citation statements)

References 21 publications

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“…Most of the N in the STE was present as NH 4 –N (83.7% of TN), followed by TON (15.7% of TN), and NO x –N (0.6% of TN). The distribution of N forms in the STE was consistent with the literature values (70–90% NH 4 –N and 10–30% TON) of typical residential wastewater (McCray et al, 2005; Heatwole and McCray 2007; Robertson, 2012; Richard et al, 2014; Siegrist et al, 2014).…”

Section: Resultssupporting

confidence: 89%

“…This decrease in NH 4 –N is attributed primarily to nitrification in the drainfield, as is discussed in the next paragraph. Other secondary processes may include NH 4 adsorption and coupled nitrification–denitrification as STE was dosed every 4 h, creating alternative aerobic and anaerobic conditions (Richard et al, 2014).…”

Section: Resultsmentioning

confidence: 99%

“…Effluent‐borne N can be attenuated in the OWTS drainfields due to dilution with infiltrating rainfall and gaseous loss of N (Hinkle et al, 2008; Meeroff et al, 2008; Katz et al, 2010; Richard et al, 2014). The cyclic aerobic and anaerobic conditions in the drainfield due to the intermittent effluent dosing cause soil moisture to fluctuate, which, in turn, affects mineralization, nitrification, and denitrification (McKinley and Siegrist, 2010).…”

mentioning

confidence: 99%

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Fate of Effluent‐Borne Nitrogen in the Mounded Drainfield of an Onsite Wastewater Treatment System

2015

Vadose Zone Journal

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Core Ideas Water filled porosity (WFP) controlled N dynamics in the drainfields. Sand layer was hotspot for nitrification due to 0.07–0.32 WFP. Soil layer was hotspot for denitrification due to 0.55–0.91 WFP. Organic N was mobile in the vadose zone and leached below drainfields. Onsite wastewater treatment systems (OWTS), commonly known as septic systems, are increasingly recognized as a potential source of nitrogen in the shallow groundwater. Our objective was to investigate the effect of hydrological and biogeochemical factors in the vadose zone on the fate of effluent‐borne N in the drainfields of a drip‐dispersal OWTS. Three lysimeters (152.4 cm long, 91.4 cm wide, and 91.4 cm high) were constructed using pressure‐treated wood to mimic OWTS drainfields. Each lysimeter had three distinct layers of gravel–sand mixture, soil, and commercial sand. A drip tube, which was covered with commercial sand before planting St. Augustine grass (Stenotaphrum Trin.) on the top and sides of the lysimeters, dispersed 9 L of septic tank effluent (STE) per day on top of the stacked layers. Each lysimeter was instrumented with 10 multi‐probe sensors to determine the water content, electrical conductivity (EC), and temperature in the center and sides of sand and soil layers. Leachate samples were collected over 67 events, which consisted of one sample every 24 h for 15 d (n = 15) and weekly flow‐weighted composite samples (n = 52). In all events, the pH, EC, and chloride were lower in the leachate than STE. Daily multi‐probe data showed that EC was greater in the center than sides of the lysimeters due to more STE interaction. Sensor water content data were used to calculate water filled porosity (WFP), which was greater in the soil (0.55–0.9) than sand (0.07–0.32) due to the textural differences. Mean total N was 70 mg L−1 in the STE, which reduced to 27.4 mg L−1 in the leachate likely due to the denitrification in the soil layer. The dominance of NOx–N in the leachate (61%) as compared to STE (0.6%) was attributed to the nitrification in the sand layer. Higher proportion of organic N in the leachate (39%) than STE (16%) suggests that organic N was mobile in the vadose zone and leached below the drainfields. We conclude that hydrological and biogeochemical controls in the vadose zone play an important role in N transformations and transport of NOx–N and organic N below OWTS drainfields.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Fate of Effluent‐Borne Nitrogen in the Mounded Drainfield of an Onsite Wastewater Treatment System

2015

Vadose Zone Journal

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“…Denitrification processes that do not require an organic C source may also be active in the mesocosms. For example, Thiobacillus denitrificans can reduce NO 3 to N 2 , oxidizing reduced S compounds under anaerobic conditions instead of organic C (Robertson and Kuenen, 1991; Kanter et al, 1998), which could contribute to N removal in all drainfield types. This process has been observed under acidic conditions in soil (Germida et al, 1991).…”

Section: Resultsmentioning

confidence: 99%

Evaluation of Water Quality Functions of Conventional and Advanced Soil-Based Onsite Wastewater Treatment Systems

et al. 2015

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Shallow narrow drainfields are assumed to provide better wastewater renovation than conventional drainfields and are used for protection of surface and ground water. To test this assumption, we evaluated the water quality functions of two advanced onsite wastewater treatment system (OWTS) drainfields-shallow narrow (SND) and Geomat (GEO)-and a conventional pipe and stone (P&S) drainfield over 12 mo using replicated ( = 3) intact soil mesocosms. The SND and GEO mesocosms received effluent from a single-pass sand filter, whereas the P&S received septic tank effluent. Between 97.1 and 100% of 5-d biochemical oxygen demand (BOD), fecal coliform bacteria, and total phosphorus (P) were removed in all drainfield types. Total nitrogen (N) removal averaged 12.0% for P&S, 4.8% for SND, and 5.4% for GEO. A mass balance analysis accounted for 95.1% (SND), 94.1% (GEO), and 87.6% (P&S) of N inputs. When the whole treatment train (excluding the septic tank) is considered, advanced systems, including sand filter pretreatment and SND or GEO soil-based treatment, removed 99.8 to 99.9% of BOD, 100% of fecal coliform bacteria and P, and 26.0 to 27.0% of N. In contrast, the conventional system removed 99.4% of BOD and 100% of fecal coliform bacteria and P but only 12.0% of N. All drainfield types performed similarly for most water quality functions despite differences in placement within the soil profile. However, inclusion of the pretreatment step in advanced system treatment trains results in better N removal than in conventional treatment systems despite higher drainfield N removal rates in the latter.

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“…[5] in Table 1). Both nitrification and denitrification contribute to N 2 O emissions due to alternating oxic/anoxic conditions in the leach field and possible microsites (Richard et al, 2014).…”

Section: Key Biogeochemical Transformations In Septic Systems That Comentioning

confidence: 99%

Greenhouse Gas Emissions from Septic Systems in New York State

et al. 2016

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Onsite septic systems use microbial processes to eliminate organic wastes and nutrients such as nitrogen; these processes can contribute to air pollution through the release of greenhouse gases (GHGs). Current USEPA estimates for septic system GHG emissions are based on one study conducted in north-central California and are limited to methane; therefore, the contribution of these systems to the overall GHG emission budget is unclear. This study quantified and compared septic system GHG emissions from the soil over leach fields and the roof vent, which are the most likely locations for gas emissions during normal septic system operation. At each of eight septic systems, we measured fluxes of CH, CO, and NO using a static chamber method. The roof vent released the majority of septic system gas emissions. In addition, the leach field was a significant source of NO fluxes. Comparisons between leach field and vent emissions suggest that biological processes in the leach field soil may influence the type and quantity of gas released. Overall, our results suggest that (i) revisions are needed in USEPA guidance (e.g., septic systems are not currently listed as a source of NO emissions) and (ii) similar studies representing a wider range of climatic and geographic settings are needed. The total vent, sand filter, and leach field GHG emissions were 0.17, 0.045, and 0.050 t CO-equivalents capita yr, respectively. In total, this represents about 1.5% of the annual carbon footprint of an individual living in the United States.

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Mechanisms of Ammonium Transformation and Loss in Intermittently Aerated Leachfield Soil

Cited by 9 publications

References 21 publications

Fate of Effluent‐Borne Nitrogen in the Mounded Drainfield of an Onsite Wastewater Treatment System

Fate of Effluent‐Borne Nitrogen in the Mounded Drainfield of an Onsite Wastewater Treatment System

Evaluation of Water Quality Functions of Conventional and Advanced Soil-Based Onsite Wastewater Treatment Systems

Greenhouse Gas Emissions from Septic Systems in New York State

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