Microbial tracers to evaluate an on-site shallow-placed low pressure distribution system

Ijzerman, M. Marian; Hagedorn, Charles; Reneau, R. B.

doi:10.1016/0043-1354(93)90032-d

Cited by 12 publications

(7 citation statements)

References 7 publications

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“…Escherichia coli (ATCC 25922) was the experimental bacterial strain. An antibiotic‐resistant mutant of this strain was used by Ijzerman et al (1993) in a field study of bacterial transport from a septic leach line. E. coli is a well‐characterized, Gram‐negative, typical representative of the coliform bacteria, which are used as indicators of fecal contamination.…”

Section: Methodsmentioning

confidence: 99%

Transport of Escherichia coli in Sand Columns with Constant and Changing Water Contents

Powelson

Mills

2001

J of Env Quality

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Understanding how changes in volumetric water content (theta) affect bacterial adsorption could help reduce transport of pathogenic and indicator bacteria that may be present in infiltrating wastewater. Three flow regimes that simulated infiltration from a household septic system were evaluated: saturated, unsaturated with a constant volumetric water content theta (constant unsaturated flow), and unsaturated with cyclic changes in theta (variable unsaturated flow). Escherichia coli was suspended in artificial sewage (AS) and applied as step inputs to sand columns, with regular interruptions in input for variable unsaturated flow. A transport model was fit to the saturated and constant unsaturated flow breakthrough curves to determine retardation (R), the first-order filtration coefficient (mu), and the maximum outflow relative concentration (Cmax). The total cells transported as a fraction of input (tau) in all three flow regimes was calculated. Constant unsaturated flow resulted in a significantly lower Cmax (0.633) in comparison with saturated flow (0.803, P < or = 0.05), although unsaturated mu (0.0693 h(-1)) was not significantly different from saturated mu (0.0259 h(-1)). Constant unsaturated flow also resulted in a significantly smaller tau (0.617) than saturated (0.806) or variable unsaturated flow (0.734). In variable unsaturated flow, cell concentrations were out of phase with theta--as the column drained, cell concentrations in the outflow increased; and when a pulse of suspension was applied, cell concentrations decreased. Constant unsaturated flow is probably the best for removal of pathogenic bacteria because this regime resulted in lower maximum concentrations of E. coli and greater cell removal, in comparison with saturated and variable unsaturated flow.

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Section: Methodsmentioning

confidence: 99%

Transport of Escherichia coli in Sand Columns with Constant and Changing Water Contents

Powelson

Mills

2001

J of Env Quality

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“…OWS installed in soils with higher percentages of fine-textured materials such as silt and clay, typically are more efficient at reducing microbial concentrations than OWS installed in sandy soils, due to the increased reactive surface area and residence time [7,14,15]. Research has also suggested that higher wastewater loading rates may lead to decreased treatment [8,[16][17][18] and that OWS that utilize low pressure pipe (LPP) distribution can more efficiently treat wastewater constituents such as bacteria relative to gravity flow effluent distribution systems [16,19,20]. LPP systems include a septic tank and pump tank, a pump that delivers effluent to the drainfield trenches via a pressure manifold connected to small diameter (2.54 to 5.08 cm) PVC conveyance pipes (laterals) that extend the length of each trench ( Figure 1).…”

Section: Introductionmentioning

confidence: 99%

“…The conveyance pipes are not capped at the end, and thus often deliver more wastewater to the front of the trenches than an LPP system. Because some of the earlier studies suggested that LPP systems could perform better than conventional OWS [16,19,20], there are less stringent siting requirements for LPP systems relative to conventional systems with distribution boxes in North Carolina. For example, in sandy areas, LPP systems can be installed in soils with 15 cm less soil depth and separation to groundwater than conventional OWS [21], and LPP systems typically require about 25%-30% less overall drainfield area than conventional trench systems with distribution boxes [21].…”

Section: Introductionmentioning

confidence: 99%

Spatial Distribution of Fecal Indicator Bacteria in Groundwater beneath Two Large On-Site Wastewater Treatment Systems

Humphrey

O’Driscoll

Harris

2014

Water

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On-site wastewater treatment systems (OWS) are a common means of wastewater treatment in coastal North Carolina, where the soils are sandy and groundwater is relatively close to the surface (<5 m). Wastewater contains elevated concentrations of pathogenic microorganisms that can contaminate groundwater and surface water if OWS are not operating efficiently and distributing wastewater equally to all drainfield trenches. The objectives of this study were to compare the distribution of fecal indicator bacteria (FIB) in groundwater beneath a large low-pressure pipe (LPP) OWS and a large pump to distribution box system, and to determine the effectiveness of the systems in reducing FIB including total coliform, E. coli, and enterococci. Monitoring wells were installed at the fronts and ends of the drainfields for sample collection. Groundwater beneath the LPP had a more homogeneous spatial distribution of E. coli and enterococci concentrations and the specific conductivity of groundwater was also more uniform relative to groundwater beneath the distribution box system. Both systems were effective (>99%) at reducing FIB concentrations before discharge to groundwater. Results indicate that the LPP did enhance the distribution of FIB in groundwater beneath the drainfield area relative to the pump to distribution box system. Although the LPP system had a vadose zone over 2 m thinner than the pump to distribution box system, FIB treatment was similar. Enterococci was the most resilient FIB of the three tested.

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“…To conclusively determine the effects (if any) of injection well and septic practices on the surface and subsurface waters of Key Largo, a well-designed tracer study was required. Tracer studies have been effectively used to investigate the migration of wastewater and efficiency of sewage treatment (5). Using this approach, we have studied the migration of simulated wastes in the subsurface by seeding a septic tank and a simulated injection well with different bacteriophages and following their fate as a function of time.…”

mentioning

confidence: 99%

Viral tracer studies indicate contamination of marine waters by sewage disposal practices in key largo, Florida

Paul¹,

Rose²,

Brown³

et al. 1995

Appl Environ Microbiol

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Domestic wastewater disposal practices in the Florida Keys are primarily limited to on-site disposal systems such as septic tanks, injection wells, and illegal cesspits. Poorly treated sewage is thus released into the highly porous subsurface Key Largo limestone matrix. To investigate the fate and transport of sewage in the subsurface environment and the potential for contamination of marine surface waters, we employed bacteriophages as tracers in a domestic septic system and a simulated injection well in Key Largo, Florida. Transport of bacteriophage ⌽HSIC-1 from the septic tank to adjacent surface canal waters and outstanding marine waters occurred in as little as 11 and 23 h, respectively. Transport of the Salmonella phage PRD1 from the simulated injection well to a canal adjacent to the injection site occurred in 11.2 h. Estimated rates of migration of viral tracers ranged from 0.57 to 24.2 m/h, over 500-fold greater than flow rates measured previously by subsurface flow meters in similar environments. These results suggest that current on-site disposal practices can lead to contamination of the subsurface and surface marine waters in the Keys.

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Microbial tracers to evaluate an on-site shallow-placed low pressure distribution system

Cited by 12 publications

References 7 publications

Transport of Escherichia coli in Sand Columns with Constant and Changing Water Contents

Transport of Escherichia coli in Sand Columns with Constant and Changing Water Contents

Spatial Distribution of Fecal Indicator Bacteria in Groundwater beneath Two Large On-Site Wastewater Treatment Systems

Viral tracer studies indicate contamination of marine waters by sewage disposal practices in key largo, Florida

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