Browsing by Subject "Sand filters"
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Item Performance of a Recirculating Sand Filter Wastewater Treatment System Servicing the Iron Range Resources and Rehabilitation Agency(University of Minnesota Duluth, 2003-07) McCarthy, Barbara J; Monson Geerts, Stephen DApproximately 470,000 Minnesota residences rely on the use of onsite wastewater treatment systems and 27% of these systems may be in noncompliance with state rules or are failing to the surface. As part of a demonstration project to test new technologies in the region, a recirculating sand filter with shallow dispersal trenches was constructed and monitored at the Iron Range Resources and Rehabilitation Agency (IRRRA) office building near Eveleth, Minnesota in 1998 for a flow of 600 g/d. During the study period, flow averaged 520 g/d in summer and 492 g/d in winter, or 82-87% of design flow. Approximately 750,000 gallons of septic tank effluent (STE) have passed through the system to date, with the following STE quality: 166-178 BODs, 30 mg/L TSS, 10 mg/L TP, 64-80 mg/L TN, and 1,600,000 cfu/l00mL fecal coliform bacteria (pathogen indicator organisms). After only 3 years of operation, the septic tank was nearly full (80-90% ), presumably due to a significant loading of toilet paper, since the wastewater is largely human/toilet waste. The recirculating sand filter (RSF) performed well over the nearly 3 years tested at reducing wastewater contaminants before dispersed back into the environment. Average seasonal removal rates for the RSF were 92% removal of BOD5 (15 mg/L BOD5), 84% removal of TSS (5 mg/L TSS), 82-88% removal of fecal coliform bacteria (50,000-290,000 cfu/l00mL), 13-28% removal of phosphorus (8 mg/L TP), and 20-34% removal of nitrogen (42-64 mg/L TN). Secondary treatment standards for BOD5 and TSS were routinely achieved by the RSF, although pathogen levels were elevated in the effluent. Nitrogen removal (TN) was better in summer than winter, and the effluent was also more highly nitrified during the warmer season. Nitrate levels in RSF effluent, summer and winter, were similar (20-23 mg/L NO3). Temperature of the effluents were 15°C in summer, while winter temperatures averaged 9.5°C for STE and 7.5°C for RSF effluent. During the first 3 years, a single trench (120 fl:2) was used to disperse ~518,000 gallons of RSF effluent, at a loading rate of 4g/fl:2/day, with minimal ponding in the trench. Average daily flow to the soil dispersal trench was 500 g/d, but it varied from 187 g/d to 975 g/d. During the winter 2002-2003, both the forcemain from the pump tank to the soil dispersal system and the pressure line in each trench froze. To overcome this problem, a temporary forcemain was used to route RSF effluent into the old drainfield, which had drained almost entirely after resting for 21 months.Item Performance of a Textile Filter, Polishing Sand Filter and Shallow Trench System for the Treatment of Domestic Wastewater at the Northeast Regional Correction Center(University of Minnesota Duluth, 2001-11) McCarthy, Barbara J; Monson Geerts, Stephen D; Axler, Richard P; Henneck, JeraldAn estimated half million households in Minnesota are not connected to public sewer systems. Along with the growing use and expansion of lakeshore cabins and resorts, many have the potential to degrade surface and groundwater resources as they depend primarily on individual sewage treatment systems (ISTSs) for the treatment and dispersal of domestic wastewater. Unfortunately, many are in noncompliance with state standards or are hydraulically failing to the surface. Effective treatment options are needed for the thousands of locations with restrictive soil and site conditions. Many of these sites occur along lakes and streams, creating a potential health hazard to swimmers and others using surface water for drinking water and recreation, leading to increased algal blooms, aesthetic nuisances and degraded fish habitat. Packed bed textile filters, coupled with a site-specific soil dispersal system, were one of several options evaluated in Minnesota. Other systems tested in northeast Minnesota have included sand filters (single pass and recirculating), peat filters (in-ground and module), subsurface flow constructed wetlands, aerobic treatment unit, standard trenches, gravel filter and drip distribution (McCarthy et al., 1997, 1998, 1999, 2001; Anderson and Gustafson, 1998; Henneck et al., 1999, 2001; Axler et al., 1999, 2000; Monson Geerts et al., 2000, 2001; Pundsack et al., 2001; Christopherson et al., 2001). This paper provides an overview of the operation and performance of a recirculating packed bed textile filter, polishing sand filter and shallow gravelless trenches at the northern Minnesota research facility.Item Performance of a Textile Filter, Polishing Sand Filter and Shallow Trench System for the Treatment of Domestic Wastewater at the Northeast Regional Correction Center(University of Minnesota Duluth, 2001-11) McCarthy, Barbara J; Monson Geerts, Stephen D; Axler, Richard P; Henneck, JeraldAn estimated half million households in Minnesota are not connected to public sewer systems. Along with the growing use and expansion of lakeshore cabins and resorts, many have the potential to degrade surface and groundwater resources as they depend primarily on individual sewage treatment systems (ISTSs) for the treatment and dispersal of domestic wastewater. Unfortunately, many are in noncompliance with state standards or are hydraulically failing to the surface. Effective treatment options are needed for the thousands of locations with restrictive soil and site conditions. Many of these sites occur along lakes and streams, creating a potential health hazard to swimmers and others using surface water for drinking water and recreation, leading to increased algal blooms, aesthetic nuisances and degraded fish habitat. Packed bed textile filters, coupled with a site-specific soil dispersal system, were one of several options evaluated in Minnesota. Other systems tested in northeast Minnesota have included sand filters (single pass and recirculating), peat filters (in-ground and module), subsurface flow constructed wetlands, aerobic treatment unit, standard trenches, gravel filter and drip distribution (McCarthy et al., 1997, 1998, 1999, 2001; Anderson and Gustafson, 1998; Henneck et al., 1999, 2001; Axler et al., 1999, 2000; Monson Geerts et al., 2000, 2001; Pundsack et al., 2001; Christopherson et al., 2001). This paper provides an overview of the operation and performance of a recirculating packed bed textile filter, polishing sand filter and shallow gravelless trenches at the northern Minnesota research facility.Item Performance of Pre-engineered Modular Peat Filters for the Treatment of Domestic Wastewater at the Northeast Regional Correction Center(University of Minnesota Duluth, 2001-11) Monson Geerts, Stephen D; McCarthy, Barbara J; Axler, Richard P; Henneck, JeraldApproximately 500,000 Minnesota residences rely on the use of onsite wastewater treatment systems and >50% of these systems may be in noncompliance with state rules or are failing to the surface. A research site at the Northeast Regional Correction Center near Duluth was established in 1995, involving~ 50 private and public sector partners, to design, construct, and monitor the performance of advanced onsite treatment systems. The systems were generally designed to treat 250 gal/day of septic tank effluent from single family homes to meet secondary treatment standards; 25 mg/L total suspended solids (TSS), 30 mg/L biochemical oxygen demand (BOD5), and 200 cfu/lOOmL fecal coliform bacteria. In 1998, pre-engineered peat filters (Puraflo®, Bord Na M6na, Inc.) were installed to compare the performance of a standard Irish peat to a Bord Na M6na specified Minnesota peat. Initially, the peat filters were operated in the recirculating mode for enhanced nitrogen removal, but were changed to single-pass mode after ponding occurred. Hydraulic failure likely resulted due to cold temperatures (since the modules were not insulated) coupled with high strength waste. With minor design modifications, including foam-insulated covers, the single-pass peat filters have operated without problems. In the recirculating mode, seasonal removal rates for both types of peat ranged 86-97% TSS, 94- 97% BOD5 96-99% fecal coliform bacteria, 6-20% total phosphorus (TP), and 31-45% total nitrogen (TN). As single-pass filters, removal rates were comparable at 89-96% TSS, 95-98% BOD5 >99% fecal coliform bacteria, 94-99% coliphages, 0-20% TP, and 24-37% TN for both peat types. The module Puraflo® peat filter systems, using both the standard Irish peat and a Minnesota peat, performed comparably and generally exceeded secondary treatment standards.