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Gurpal S Toor - One of the best experts on this subject based on the ideXlab platform.
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micropollutants in groundwater from Septic Systems transformations transport mechanisms and human health risk assessment
Water Research, 2017Co-Authors: Yunya Yang, Gurpal S Toor, Chris P Wilson, Clinton F WilliamsAbstract:Abstract Septic Systems may contribute micropollutants to shallow groundwater and surface water. We constructed two in situ conventional drainfields (drip dispersal and gravel trench) and an advanced drainfield of Septic Systems to investigate the fate and transport of micropollutants to shallow groundwater. Unsaturated soil-water and groundwater samples were collected, over 32 sampling events (January 2013 to June 2014), from the drainfields (0.31–1.07 m deep) and piezometers (3.1–3.4 m deep). In addition to soil-water and groundwater, effluent samples collected from the Septic tank were also analyzed for 20 selected micropollutants, including wastewater markers, hormones, pharmaceuticals and personal care products (PPCPs), a plasticizer, and their transformation products. The removal efficiencies of micropollutants from Septic tank effluent to groundwater were similar among three Septic Systems and were 51–89% for sucralose and 53–>99% for other micropollutants. Even with high removal rates within the drainfields, six PPCPs and sucralose with concentrations ranging from
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a review of the fate and transport of nitrogen phosphorus pathogens and trace organic chemicals in Septic Systems
Critical Reviews in Environmental Science and Technology, 2017Co-Authors: Mary G Lusk, Yunya Yang, Gurpal S Toor, Sara Mechtensimer, Mriganka De, Thomas A ObrezaAbstract:ABSTRACTA large population living in suburban and rural areas in the world uses Septic Systems, also called onsite wastewater treatment Systems, to dispose of household wastewater. In a conventional Septic system, the wastewater flows from a household to a Septic tank, where solids settle and a clarified effluent is produced. This effluent is dispersed into the soil for further treatment and can be a potential source of various contaminants such as nutrients, pathogens, and a new class of compounds known as trace organic chemicals (TOrCs) in shallow groundwater and surface waters. We review the current state of the science on the fate and transport of three groups of contaminants—nutrients (nitrogen, phosphorus), pathogens, and TOrCs—and water quality impacts associated with these contaminants in conventional Septic Systems. We also discuss alternative technologies that may be employed when site conditions or environmental needs preclude the use of conventional Septic Systems.
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nitrogen transformations in the mounded drainfields of drip dispersal and gravel trench Septic Systems
Ecological Engineering, 2017Co-Authors: Mriganka De, Gurpal S ToorAbstract:Abstract Appropriate drainfield design in Septic Systems can be an effective tool to optimize nitrogen (N) removal and protect public and environmental health. Our objective was to investigate how the conventional drainfield designs affect N transformations in Septic Systems. We investigated the N treatment efficiency of two in-situ drainfield designs (6.1 m long and 0.61 m wide), which were constructed by (1) adding 30.5 cm sand on top of natural soil (referred to as drip dispersal) and (2) adding 30.5 cm gravel layer on top of 30.5 cm of sand and natural soil (referred to as gravel trench). A drip line was placed on top of the sand layer (in drip dispersal) or gravel layer (in gravel trench) to disperse 120 L of effluent before adding another 15.3 cm of sand layer and planting St. Augustine grass. Suction cup lysimeters, installed at 30.5, 61.0, and 106.7 cm depth below the drip lines of both drainfields, were used to collect soil-water samples over 64 events (May 2012–December 2013). Mean total N concentration was 66 mg L −1 in the effluent, which significantly (p x –N in the gravel trench (45.6 ± 1.3 mg L −1 ) than drip dispersal (28 ± 3.1 mg L −1 ) was attributed to the presence of additional 30.5 cm gravel layer that caused greater oxygen diffusion resulting in lower gaseous N loss via coupled nitrification-denitrification. Total organic N was not significantly different between the effluent (7.3 mg L −1 ; n = 61) and drainfields (5.5–6.4 mg L −1 ; n = 192) suggesting that organic N forms remained mobile in the drainfields. We conclude that the drip dispersal was more effective at attenuating NO x –N than gravel trench due to the greater gaseous N loss and should be preferred in areas with shallow groundwater (
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Septic Systems contribution to phosphorus in shallow groundwater field scale studies using conventional drainfield designs
PLOS ONE, 2017Co-Authors: Sara Mechtensimer, Gurpal S ToorAbstract:Septic Systems can be a potential source of phosphorus (P) in groundwater and contribute to eutrophication in aquatic Systems. Our objective was to investigate P transport from two conventional Septic Systems (drip dispersal and gravel trench) to shallow groundwater. Two new in-situ drainfields (6.1 m long by 0.61 m wide) with a 3.72 m2 infiltrative surface were constructed. The drip dispersal drainfield was constructed by placing 30.5 cm commercial sand on top of natural soil and the gravel trench drainfield was constructed by placing 30.5 cm of gravel on top of 30.5 cm commercial sand and natural soil. Suction cup lysimeters were installed in the drainfields (at 30.5, 61, 106.7 cm below infiltrative surface) and piezometers were installed in the groundwater (>300 cm below infiltrative surface) to capture P dynamics from the continuum of unsaturated to saturated zones in the Septic Systems. Septic tank effluent (STE), soil-water, and groundwater samples were collected for 64 events (May 2012-Dec 2013) at 2 to 3 days (n = 13), weekly (n = 29), biweekly (n = 17), and monthly (n = 5) intervals. One piezometer was installed up-gradient of the drainfields to monitor background groundwater (n = 15). Samples were analyzed for total P (TP), orthophosphate-P (PO4-P), and other-P (TP-PO4-P). The gravel trench drainfield removed significantly (p 300 cm in the groundwater, both Systems had similar TP reductions of >97%. After 18 months of STE application, there was no significant increase in groundwater TP concentrations in both Systems. We conclude that both drainfield designs are effective at reducing P transport to shallow groundwater.
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Septic Systems as hot spots of pollutants in the environment fate and mass balance of micropollutants in Septic drainfields
Science of The Total Environment, 2016Co-Authors: Yunya Yang, Gurpal S Toor, Chris P Wilson, Clinton F WilliamsAbstract:Abstract Septic Systems, a common type of onsite wastewater treatment Systems, can be an important source of micropollutants in the environment. We investigated the fate and mass balance of 17 micropollutants, including wastewater markers, hormones, pharmaceuticals and personal care products (PPCPs) in the drainfield of a Septic system. Drainfields were replicated in lysimeters (1.5 m length, 0.9 m width, 0.9 m height) and managed similar to the field practice. In each lysimeter, a drip line dispersed 9 L of Septic tank effluent (STE) per day (equivalent to 32.29 L/m 2 per day). Fourteen micropollutants in the STE and 12 in the leachate from drainfields were detected over eight months. Concentrations of most micropollutants in the leachate were low ( 85% of the added micropollutants except for sucralose were attenuated in the drainfield. We discovered that sorption was the key mechanism for retention of carbamazepine and partially for sulfamethoxazole, whereas microbial degradation likely attenuated acetaminophen in the drainfield. This data suggests that sorption and microbial degradation limited transport of micropollutants from the drainfields. However, the leaching of small amounts of micropollutants indicate that Septic Systems are hot-spots of micropollutants in the environment and a better understanding of micropollutants in Septic Systems is needed to protect groundwater quality.
John A Cherry - One of the best experts on this subject based on the ideXlab platform.
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In Situ Denitrification of Septic‐System Nitrate Using Reactive Porous Media Barriers: Field Trials
Ground Water, 1995Co-Authors: William D. Robertson, John A CherryAbstract:A new alternative Septic-system design is presented utilizing reactive porous media barriers for passive in situ attenuation of NO3−. The reactive material consists of solid organic carbon (sawdust) which promotes NO3- attenuation by heterotrophic denitrification. Four field trials are discussed demonstrating two barrier configurations: as a horizontal layer positioned in the vadose zone below a conventional Septic-system infiltration bed and as a vertical wall intercepting a horizontally flowing downgradient plume. During one year of operation both barrier configurations have been successful in substantial attenuation (60 to 100%) of input NO3- levels of up to 125 mg/1 as N. The horizontal layer configuration can be readily installed during the construction of new infiltration beds, whereas the vertical wall configuration may be more appropriate for retrofitting existing Septic Systems where NO3- contamination has already occurred. The layer configuration allows the flexibility of constructing the barrier in the vadose zone by using coarse silt or fine sand matrix material that has the ability to remain tension-saturated, and thus anaerobic, even when positioned above the water table. Advantages of the barrier system are that it is simple to construct, no surface structures or additional plumbing are necessary, and treatment is passive requiring no energy consumption and little or no maintenance. Mass balance calculations and preliminary results suggest that conveniently sized barriers have the potential to last for decades without replenishment of the reactive material.
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biogeochemical evolution of domestic waste water in Septic Systems 1 conceptual model
Ground Water, 1994Co-Authors: Sheryl R Wilhelm, Sherry L Schiff, John A CherryAbstract:This paper presents a conceptual model, developed by synthesizing the results of many researchers, which describes the geochemical evolution of domestic waste water in conventional on-site Septic Systems as the result of the interactions of a few major constituents. As described by the model, the evolution of waste water is driven by the microbially catalyzed redox reactions involving organic C and N in waste water and occurs in as many as three different redox zones. Anaerobic digestion of organic matter and production of CO2, CH4, and NH4+ predominate in the first zone, which consists mainly of the Septic tank. In the second zone, gaseous diffusion through the unsaturated sediments of the drain field supplies O2 for aerobic oxidation of organic C and NH4+ and a consequent decrease in waste-water alkalinity. The NO3− formed by NH4+ oxidation in this zone is the primary adverse impact of Septic Systems at most sites and is generally an unavoidable consequence of the proper functioning of conventional Septic Systems. If adequate O2 is not available in the drain field, aerobic digestion is incomplete, and the accumulation of organic matter may cause Septic-system failure. In the third redox zone, NO3 is reduced to N2 by the anaerobic process of denitrification. However, this setting is rarely found below Septic Systems due to a lack of labile organic C in the natural setting. Consideration of the changing redox and pH conditions in each zone aids our understanding of the fate of other constituents in Septic Systems.
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stable isotopes of oxygen and nitrogen in source identification of nitrate from Septic Systems
Ground Water, 1993Co-Authors: Ramon Aravena, M L Evans, John A CherryAbstract:Stable isotopes, 15N and 18O, have been used as tracers to differentiate a contaminant nitrate plume emanating from a single domestic Septic system, in a ground-water system characterized by high and similar nitrate content outside and inside of the contaminant plume. A good delineation of the nitrate plume of Septic origin was obtained using 15 N analysis in nitrate. The 15N content ofthe nonplunie nitrate is in agreement with the sources of nitrate: solid cattle manure, synthetic fertilizer (NH4-NO3), and soil organic nitrogen, at the study site. 18O analysis in nitrate did not provide enough isotopic contrast to permit separation of nitrate derived from the Septic system and that in the surrounding ground water, derived from agricultural fertilizer sources. 18O data indicated that nitrification of ammonium is the main process responsible for formation of nitrate at the study site. 18O in ground water clearly delineated the ground-water plume associated with the Septic system and suggest that this tracer should be considered in studies related with contaminant plumes of different origin.
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ground water contamination from two small Septic Systems on sand aquifers
Ground Water, 1991Co-Authors: W D Robertson, John A Cherry, E A SudickyAbstract:Distinct plumes of Septic system-impacted ground water at two single-family homes located on shallow unconfined sand aquifers in Ontario showed elevated levels of Cl−, NO3−, Na+, Ca2+, K+, alkalinity, and dissolved organic carbon and depressed levels of pH and dissolved oxygen. At the Cambridge site, in use 12 years, the plume had sharp lateral and vertical boundaries and was more than 130 m in length with a uniform width of about 10 m. As a result of low transverse dispersion in the aquifer, mobile plume solutes such as NO3− and Na+ occurred at more than 50 percent of the source concentrations 130 m downgradient from the Septic system. At the Muskoka site, in use three years, the plume also had discrete boundaries reflecting low transverse dispersion. After 1.5 years of system operation, the Muskoka plume began discharging to a river located 20 m from the tile field. Almost complete NOs attenuation was observed within the last 2 m of the plume flowpath before discharge to the river. This was attributed to denitrification occurring within organic matter-enriched riverbed sediments. The very weakly dispersive nature of the two aquifers was consistent with the results of recently reported natural-gradient tracer tests in sands. Therefore, for many unconfined sand aquifers, the minimum distance-to-well regulations for permitting Septic Systems in most parts of North America should not be expected to be adequately protective of well-water quality in situations where mobile contaminants such as NOs are not attenuated by chemical or microbiological processes.
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Ground‐Water Contamination from Two Small Septic Systems on Sand Aquifers
Ground Water, 1991Co-Authors: William D. Robertson, John A Cherry, E A SudickyAbstract:Distinct plumes of Septic system-impacted ground water at two single-family homes located on shallow unconfined sand aquifers in Ontario showed elevated levels of Cl−, NO3−, Na+, Ca2+, K+, alkalinity, and dissolved organic carbon and depressed levels of pH and dissolved oxygen. At the Cambridge site, in use 12 years, the plume had sharp lateral and vertical boundaries and was more than 130 m in length with a uniform width of about 10 m. As a result of low transverse dispersion in the aquifer, mobile plume solutes such as NO3− and Na+ occurred at more than 50 percent of the source concentrations 130 m downgradient from the Septic system. At the Muskoka site, in use three years, the plume also had discrete boundaries reflecting low transverse dispersion. After 1.5 years of system operation, the Muskoka plume began discharging to a river located 20 m from the tile field. Almost complete NOs attenuation was observed within the last 2 m of the plume flowpath before discharge to the river. This was attributed to denitrification occurring within organic matter-enriched riverbed sediments. The very weakly dispersive nature of the two aquifers was consistent with the results of recently reported natural-gradient tracer tests in sands. Therefore, for many unconfined sand aquifers, the minimum distance-to-well regulations for permitting Septic Systems in most parts of North America should not be expected to be adequately protective of well-water quality in situations where mobile contaminants such as NOs are not attenuated by chemical or microbiological processes.
W D Robertson - One of the best experts on this subject based on the ideXlab platform.
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review of phosphorus attenuation in groundwater plumes from 24 Septic Systems
Science of The Total Environment, 2019Co-Authors: W D Robertson, Dale R Van Stempvoort, Sherry L SchiffAbstract:Abstract This study reviews phosphorus (P) concentrations in groundwater plumes from 24 on-site wastewater treatment Systems (Septic Systems) in Ontario, Canada. Site investigations were undertaken over a 30-year period from 1988 to 2018 at locations throughout the province that encompass a variety of domestic wastewater types and geologic terrain. The review focuses on P behaviour in the drainfield sediments and in the proximal plume zones, within 10 m of the drainfields, where plume conditions were generally at steady state. At these sites, mean soluble reactive phosphorus (SRP) values in the Septic tank effluent ranged from 1.8 to 13.8 mg/L and averaged 8.4 mg/L. Phosphorus removal in the drainfields averaged 90% at sites where sediments were non calcareous (13 sites) and 66% at sites where sediments were calcareous (11 sites). Removal considering both the drainfields and proximal plume zones, averaged 97% at the non-calcareous sites and 69% at the calcareous sites, independent of the site age or loading rate. At 17 of the 24 sites, mean SRP concentrations in the proximal groundwater plumes (within 10 m) declined to ≤1 mg/L, which is a common treatment level for P at sewage treatment plants. Zones of P accumulation were present in almost all of the drainfields, where sand grains exhibited distinct secondary coatings containing P, demonstrating that mineral precipitation was likely the dominant cause of the P retention observed at these sites. This review confirms the often robust capacity for phosphorus removal in properly functioning Septic Systems. At the majority of these sites (17/24), P retention meets or exceeds removal that would normally be achieved during conventional sewage treatment. This challenges the necessity of avoiding Septic system use in favor of communal sewer Systems, when limiting phosphorus loading to nearby water courses is a principal or major concern.
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phosphorus and nitrogen loading to lake huron from Septic Systems at grand bend on
Journal of Great Lakes Research, 2019Co-Authors: Simon Baer, W D Robertson, John Spoelstra, Sherry L SchiffAbstract:Abstract Groundwater nutrient loading to L. Huron was assessed along a 1.7 km section of beach at Grand Bend, ON, Canada, where Septic Systems are used for wastewater disposal. The artificial sweetener acesulfame (ACE) was detected in all groundwater samples (7–842 ng/L, n = 78), revealing that the entire surficial aquifer was impacted by Septic system wastewater. Nitrate concentrations (3.5 ± 1.4 mg/L, n = 78) were correlated with ACE (r2 = 0.54), indicating that Septic Systems contribute to nitrate loading in the aquifer. Chloride was also elevated (37 ± 11 mg/L, n = 78), but was not correlated with ACE (r2 = 0.008), indicating a non wastewater source was dominant, likely road salt. Soluble reactive phosphorus (SRP) values were low (5.3 ± 9.3 μg/L, n = 77) and were not correlated with ACE (r2 = 0.006). Sediment profiling below two of the Septic system drain-fields, showed that the sand grains had distinct secondary coatings containing P, indicating that mineral precipitation reactions played a role in limiting P concentrations present in the aquifer. Groundwater nutrient loading to the lake was estimated at 13,000 kg N/year from NO3− and 1.9 kg P/year from SRP. These amounts are insignificant compared to nutrient loading from a stream that drains an agricultural catchment and discharges to the lake at the north end of the study site (Parkhill Creek). This calls into question, in some cases, the rationale of decommissioning properly functioning Septic Systems as a mitigation measure for reducing nutrient loading to nearby water courses.
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contribution of phosphorus to georgian bay from groundwater of a coastal beach town with decommissioned Septic Systems
Journal of Great Lakes Research, 2017Co-Authors: John Spoelstra, W D Robertson, Wynona Klemt, Sherry L SchiffAbstract:Abstract Groundwater inputs of phosphorus (P) to the Laurentian Great Lakes are poorly known, but may contribute to eutrophication and algal bloom issues. This study's objective was to assess the contribution of P to Nottawasaga Bay from the surficial sand aquifer at Wasaga Beach, representing a coastal cottage area with decommissioned Septic Systems, and how this might change with time. The first part of the study involved site-scale groundwater sampling beside 4 provincial park public washrooms. Legacy P plumes were detected at two of these sites, with one being > 30 years since decommissioning. P transport calculations including sorption onto aquifer sediments indicate the majority of P plumes from the town's decommissioned Septic Systems have likely not yet reached the shoreline, > 50 years since installation, and will likely contribute P to the bay for many decades. The second part of the study consisted of broader-scale (town-wide) surveys of shallow beach groundwater. Dissolved P concentrations were ~ 50 μg/L for background groundwater (in town and reference area), which is similar to literature values. This P may have been sourced from degrading organic matter, bird droppings, or soil-aquifer minerals. Sporadic elevated concentrations up to 420 μg/L may be from legacy Septic Systems and/or natural sources. A rough calculation suggests groundwater P loading along Nottawasaga Bay's eastern shore (Wasaga Beach, 10-km; adjacent similar beaches, 40-km) is a few percent at most of that from the Nottawasaga River. Thus, it more likely affects localized periphyton and macrophyte growth rather than significantly affecting the Nottawasaga Bay P budget.
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wood based filter for nitrate removal in Septic Systems
Transactions of the ASABE, 2005Co-Authors: W D Robertson, G I Ford, P S LombardoAbstract:The recognition that Septic Systems can generate groundwater plumes with nitrate concentrations exceeding the drinking water limit has led to a need for improved nitrogen removal in Septic Systems. Long-term (3 to 5 year) monitoring results are presented for four full-scale, on-site wastewater treatment Systems using a novel porous media filter (Nitrex filter) for enhanced nitrogen removal. The filter removes nitrogen by denitrification of pretreated, nitrified, Septic tank effluent using a slowly soluble carbon source (wood byproduct material) incorporated into the filter. Results are presented for a house (sewage flow ~1 m3 d-1), a trailer park (7 m3 d-1), a communal residence (18 m3 d-1), and an inn (73 m3 d-1). In each case, the Septic tank effluent was pretreated using a sand filter, then flowed passively through the denitrification filter, and finally was dispersed in a conventional tile bed. Influent (sand filter) NO3-N concentrations, averaging 14.2 to 37.7 mg L-1, were significantly attenuated in the denitrification filters at each site (p < 0.05) by amounts ranging between 87% and 98%. Reaction rates were temperature dependent, ranging from 7 to >10 mg N L-1 d-1, and showed no sign of deteriorating with system age at any of the sites. Results support previous mass balance calculations and pilot-scale field trials, suggesting that such filters have the potential to operate for years without the need for media replenishment. These filters offer a practical solution to nitrate control in small to medium sized on-site wastewater treatment Systems where simplicity of operation and low maintenance are desirable.
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biogeochemical evolution of domestic waste water in Septic Systems 2 application of conceptual model in sandy aquifers
Ground Water, 1996Co-Authors: Sheryl R Wilhelm, Sherry L Schiff, W D RobertsonAbstract:Aqueous geochemical data from unconfined sand aquifers beneath two operating domestic Septic Systems are used to illustrate and evaluate a conceptual model of Septic-system geochemistry. This model emphasizes the changing redox and alkalinity conditions in the Septic system and the subsurface. The Septic-tank effluents flow as distinct plumes downward through the unsaturated zones and then primarily laterally in the ground-water zones. The composition of the effluent was measured at several points in each system. At each site, the Septic-tank effluent underwent aerobic oxidation in the unsaturated zone, which caused conversion of NH4+ to NO3−, organic C to CO2 and organic S to SCh42-. At the first site, calcium carbonate dissolution in the unsaturated zone buffered the acidity released by the redox reactions. In contrast, the second system was poorly buffered and the pH dropped from 6.7 to 4.9 as aerobic oxidation occurred. Below the water table a small amount of aerobic oxidation occurred at each site. Nitrate-N concentrations in the cores of both plumes were above 25 mg/1 as the plumes traveled from the Septic Systems. At the second site, the ground-water plume discharges to a river at the edge of the property. As the effluent flowed through the organic C-rich sediments of the river bed, NO3− disappeared and alkalinity increased, presumably due to denitrification. Differences in sediment composition at the two sites also led to different behaviors of Fe, Al, and possibly PO43-. The conceptual model offers an organized approach to interpreting the major geochemical trends observed in the two Systems, which are determined mostly by the well-aerated unsaturated zones below the drain fields and the amount of buffering material present in the sediments.
Sherry L Schiff - One of the best experts on this subject based on the ideXlab platform.
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Septic Systems contribute artificial sweeteners to streams through groundwater
Journal of Hydrology X, 2020Co-Authors: John Spoelstra, Sherry L Schiff, S J BrownAbstract:Abstract Artificial sweeteners are ubiquitous constituents of sanitary wastewater and are not completely attenuated by wastewater treatment processes. Consequently, artificial sweeteners are increasingly employed as a tool to detect wastewater and help evaluate its impact on aquatic environments. In rural areas, Septic Systems are known point sources of artificial sweeteners to groundwater, however the potential contribution of artificial sweeteners to streams via this pathway is unknown. We analyzed 294 samples from 173 stream sites in Southern Ontario, Canada, for acesulfame, saccharin, cyclamate, and sucralose, and found that 91% had one or more of these compounds present. The stream sites sampled did not have municipal wastewater treatment plants upstream and therefore Septic system effluent was the most likely source of the artificial sweeteners. Acesulfame, which is the most recalcitrant of the four artificial sweeteners, was by far the most ubiquitous in streams, with a 91% detection frequency, compared to 27, 8, and 3% for saccharin, cyclamate, and sucralose, respectively. Stream concentrations ranged from non-detectable to maximum values of 225, 380, 204, and 291 ng/L for acesulfame, saccharin, cyclamate, and sucralose, respectively. We calculated that water from Septic effluent contributed from
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review of phosphorus attenuation in groundwater plumes from 24 Septic Systems
Science of The Total Environment, 2019Co-Authors: W D Robertson, Dale R Van Stempvoort, Sherry L SchiffAbstract:Abstract This study reviews phosphorus (P) concentrations in groundwater plumes from 24 on-site wastewater treatment Systems (Septic Systems) in Ontario, Canada. Site investigations were undertaken over a 30-year period from 1988 to 2018 at locations throughout the province that encompass a variety of domestic wastewater types and geologic terrain. The review focuses on P behaviour in the drainfield sediments and in the proximal plume zones, within 10 m of the drainfields, where plume conditions were generally at steady state. At these sites, mean soluble reactive phosphorus (SRP) values in the Septic tank effluent ranged from 1.8 to 13.8 mg/L and averaged 8.4 mg/L. Phosphorus removal in the drainfields averaged 90% at sites where sediments were non calcareous (13 sites) and 66% at sites where sediments were calcareous (11 sites). Removal considering both the drainfields and proximal plume zones, averaged 97% at the non-calcareous sites and 69% at the calcareous sites, independent of the site age or loading rate. At 17 of the 24 sites, mean SRP concentrations in the proximal groundwater plumes (within 10 m) declined to ≤1 mg/L, which is a common treatment level for P at sewage treatment plants. Zones of P accumulation were present in almost all of the drainfields, where sand grains exhibited distinct secondary coatings containing P, demonstrating that mineral precipitation was likely the dominant cause of the P retention observed at these sites. This review confirms the often robust capacity for phosphorus removal in properly functioning Septic Systems. At the majority of these sites (17/24), P retention meets or exceeds removal that would normally be achieved during conventional sewage treatment. This challenges the necessity of avoiding Septic system use in favor of communal sewer Systems, when limiting phosphorus loading to nearby water courses is a principal or major concern.
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phosphorus and nitrogen loading to lake huron from Septic Systems at grand bend on
Journal of Great Lakes Research, 2019Co-Authors: Simon Baer, W D Robertson, John Spoelstra, Sherry L SchiffAbstract:Abstract Groundwater nutrient loading to L. Huron was assessed along a 1.7 km section of beach at Grand Bend, ON, Canada, where Septic Systems are used for wastewater disposal. The artificial sweetener acesulfame (ACE) was detected in all groundwater samples (7–842 ng/L, n = 78), revealing that the entire surficial aquifer was impacted by Septic system wastewater. Nitrate concentrations (3.5 ± 1.4 mg/L, n = 78) were correlated with ACE (r2 = 0.54), indicating that Septic Systems contribute to nitrate loading in the aquifer. Chloride was also elevated (37 ± 11 mg/L, n = 78), but was not correlated with ACE (r2 = 0.008), indicating a non wastewater source was dominant, likely road salt. Soluble reactive phosphorus (SRP) values were low (5.3 ± 9.3 μg/L, n = 77) and were not correlated with ACE (r2 = 0.006). Sediment profiling below two of the Septic system drain-fields, showed that the sand grains had distinct secondary coatings containing P, indicating that mineral precipitation reactions played a role in limiting P concentrations present in the aquifer. Groundwater nutrient loading to the lake was estimated at 13,000 kg N/year from NO3− and 1.9 kg P/year from SRP. These amounts are insignificant compared to nutrient loading from a stream that drains an agricultural catchment and discharges to the lake at the north end of the study site (Parkhill Creek). This calls into question, in some cases, the rationale of decommissioning properly functioning Septic Systems as a mitigation measure for reducing nutrient loading to nearby water courses.
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contribution of phosphorus to georgian bay from groundwater of a coastal beach town with decommissioned Septic Systems
Journal of Great Lakes Research, 2017Co-Authors: John Spoelstra, W D Robertson, Wynona Klemt, Sherry L SchiffAbstract:Abstract Groundwater inputs of phosphorus (P) to the Laurentian Great Lakes are poorly known, but may contribute to eutrophication and algal bloom issues. This study's objective was to assess the contribution of P to Nottawasaga Bay from the surficial sand aquifer at Wasaga Beach, representing a coastal cottage area with decommissioned Septic Systems, and how this might change with time. The first part of the study involved site-scale groundwater sampling beside 4 provincial park public washrooms. Legacy P plumes were detected at two of these sites, with one being > 30 years since decommissioning. P transport calculations including sorption onto aquifer sediments indicate the majority of P plumes from the town's decommissioned Septic Systems have likely not yet reached the shoreline, > 50 years since installation, and will likely contribute P to the bay for many decades. The second part of the study consisted of broader-scale (town-wide) surveys of shallow beach groundwater. Dissolved P concentrations were ~ 50 μg/L for background groundwater (in town and reference area), which is similar to literature values. This P may have been sourced from degrading organic matter, bird droppings, or soil-aquifer minerals. Sporadic elevated concentrations up to 420 μg/L may be from legacy Septic Systems and/or natural sources. A rough calculation suggests groundwater P loading along Nottawasaga Bay's eastern shore (Wasaga Beach, 10-km; adjacent similar beaches, 40-km) is a few percent at most of that from the Nottawasaga River. Thus, it more likely affects localized periphyton and macrophyte growth rather than significantly affecting the Nottawasaga Bay P budget.
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Artificial Sweeteners Reveal Septic System Effluent in Rural Groundwater.
Journal of Environmental Quality, 2017Co-Authors: John Spoelstra, Natalie D. Senger, Sherry L SchiffAbstract:It has been widely documented that municipal wastewater treatment plant effluents are a major source of artificial sweeteners to surface waters. However, in rural areas, the extent to which Septic Systems contribute these same compounds to groundwater aquifers is largely unknown. We examined the occurrence of four commonly used artificial sweeteners in an unconfined sand aquifer that serves as a water supply for rural residents, as a receptor of domestic wastewater from Septic Systems, and as a source of baseflow to the Nottawasaga River, ON, Canada. Groundwater from the Lake Algonquin Sand Aquifer in the southern Nottawasaga River Watershed was collected from private domestic wells and as groundwater seeps discharging along the banks of the Nottawasaga River. Approximately 30% of samples had detectable levels of one or more artificial sweeteners, indicating the presence of water derived from Septic system effluent. Using acesulfame concentrations to estimate the fraction of Septic effluent in groundwater samples, ∼3.4 to 13.6% of the domestic wells had 1% or more of their well water being derived from Septic system effluent. Similarly, 2.0 to 4.7% of the groundwater seeps had a Septic effluent contribution of 1% or more. No relationship was found between the concentration of acesulfame and the concentration of nitrate, ammonium, or soluble reactive phosphorus in the groundwater, indicating that Septic effluent is not the dominant source of nutrients in the aquifer. It is expected that the occurrence of artificial sweeteners in shallow groundwater is widespread throughout rural areas in Canada.
G M Baumer - One of the best experts on this subject based on the ideXlab platform.
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statewide gis census data assessment of nitrogen loadings from Septic Systems in pennsylvania
Journal of Environmental Quality, 1996Co-Authors: Egide Nizeyimana, Gary W Petersen, M C Anderson, Barry Michael Evans, James M Hamlett, G M BaumerAbstract:Despite the role of Septic Systems in surface and groundwater N contamination, little statewide information has been collected or is available on the amount of N pollution from Septic Systems. This study reports on the development of a methodology to assess N released from Septic Systems at the state level and presents results of N loading estimates in Pennsylvania watersheds. The methodology describes steps to compute N loadings per watershed unit area within a Geographic Information System (GIS) framework based on (i) information on Septic Systems and population from the 1990 Census data, (ii) soil limitations to proper purification of Septic system effluent acquired from the State Soil Geographic (STATSGO) data base, and (iii) daily N estimates per capita in Septic system effluent from the literature. In this study, watersheds were ranked from 1 to 104 and grouped into three significantly different classes (high, medium, and low) according to their N loadings. The N loading ranges corresponding to these classes were 1.16 to 0.71 kg ha -1 yr -1 , 0.66 to 0.41 kg ha -1 yr -1 , and 0.38 to 0.03 kg ha -1 yr -1 , respectively. High-producing watersheds were generally located in suburbs adjacent to larger metropolitan areas. The watershed ranking, groups, and N loading results provided by this methodology can be combined with similar information from agriculture, atmospheric deposition, etc. in the attempt to account for all sources of nonpoint N pollution in a state or region.
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Statewide GIS/Census Data Assessment of Nitrogen Loadings from Septic Systems in Pennsylvania
Journal of Environmental Quality, 1996Co-Authors: Egide Nizeyimana, Gary W Petersen, M C Anderson, Barry Michael Evans, James M Hamlett, G M BaumerAbstract:Despite the role of Septic Systems in surface and groundwater N contamination, little statewide information has been collected or is available on the amount of N pollution from Septic Systems. This study reports on the development of a methodology to assess N released from Septic Systems at the state level and presents results of N loading estimates in Pennsylvania watersheds. The methodology describes steps to compute N loadings per watershed unit area within a Geographic Information System (GIS) framework based on (i) information on Septic Systems and population from the 1990 Census data, (ii) soil limitations to proper purification of Septic system effluent acquired from the State Soil Geographic (STATSGO) data base, and (iii) daily N estimates per capita in Septic system effluent from the literature. In this study, watersheds were ranked from 1 to 104 and grouped into three significantly different classes (high, medium, and low) according to their N loadings. The N loading ranges corresponding to these classes were 1.16 to 0.71 kg ha -1 yr -1 , 0.66 to 0.41 kg ha -1 yr -1 , and 0.38 to 0.03 kg ha -1 yr -1 , respectively. High-producing watersheds were generally located in suburbs adjacent to larger metropolitan areas. The watershed ranking, groups, and N loading results provided by this methodology can be combined with similar information from agriculture, atmospheric deposition, etc. in the attempt to account for all sources of nonpoint N pollution in a state or region.
