Viral and bacterial contamination of groundwater from on-site sewage treatment systems

1997 ◽  
Vol 35 (11-12) ◽  
pp. 141-146 ◽  
Author(s):  
J. E. Scandura ◽  
M. D. Sobsey
Keyword(s):  
Wastewater Treatment ◽  
Ground Water ◽  
Faecal Coliform ◽  
Coliform Bacteria ◽  
Septic Tank ◽  
Septic Systems ◽  
Coastal Plains ◽  
Hydraulic Residence Time ◽  
Monitoring Wells ◽  
Wastewater Treatment Systems

On-site septic tank-soil absorption systems treating domestic wastewater have contaminated groundwaters with enteric viruses and other pathogens and caused drinking waterborne outbreaks. The factors influencing pathogen transport, survival and fate at on-site wastewater treatment systems remain inadequately characterised. We studied the survival and transport of a model enterovirus (BE-1) and faecal coliform bacteria in four on-site wastewater treatment systems (three conventional and one low pressure, small pipe diameter, pumped system) located in sandy soils typical of the coastal plains. Septic system wastewaters were seeded seasonally with known amounts of BE-1 and the fate of BE-1, faecal coliforms and other wastewater constituents were followed for three months in seeded wastewaters and groundwaters of drainfield monitoring wells. BE-1 levels in seeded wastewaters declined exponentially by kinetics consistent with a 3d hydraulic residence time. BE-1 was detected in ground waters of monitoring wells as early as 1d after seeding and persisted up to two months. Virus detection in ground water was greater in winter than in summer and was positively associated with proximity to septic effluent distribution lines, drainfield soils with the lowest clay content, elevated ground water pH and shallower vadose zones. Viruses were not strongly associated with either distance from septic tank or faecal coliform levels in groundwater. Under optimum conditions, virus reductions were as high as 9 log10, but in systems with the most coarse (sand) soils and highest water tables (most shallow vadose zones), there was extensive ground water contamination by viruses and other wastewater constituents. Under some conditions, septic systems in sandy coastal plains soils can contaminate ground water with viruses and other wastewater constituents.

scholarly journals Effect of alternative on-site wastewater treatment on the viability and culturability of Salmonella choleraesuis

2005 ◽  
Vol 3 (1) ◽  
pp. 1-14 ◽  
Author(s):  
J. W. Pundsack ◽  
R. E. Hicks ◽  
R. P. Axler
Keyword(s):  
Wastewater Treatment ◽  
Cell Viability ◽  
High Strength ◽  
Viable Cell ◽  
Viable Count ◽  
Treatment System ◽  
Test Facility ◽  
Septic Tank ◽  
Salmonella Choleraesuis ◽  
Wastewater Treatment Systems

The objective of this study was to determine how alternative on-site wastewater treatment systems (i.e. subsurface flow constructed wetlands, intermittent sand filters and intermittent peat filters) affect the viability and culturability of Salmonella choleraesuis (serotype typhimurium, ATCC 23567). Influent was a high strength septic tank effluent (BOD5 240–344 mg L−1, TN ∼100 mg L−1, TP ∼ 15 mg L−1) at the Natural Resources Research Institute's (NRRI) alternative treatment system test facility in northern Minnesota. Treatment systems were inoculated with cultures of S. choleraesuis for 5–7 consecutive days in summer and winter during 1998–99. After the seeding, outflow samples were taken until Salmonella counts were sustained at background levels. In addition to culture-based enumeration, S. choleraesuis abundances were also measured using fluorescent in situ hybridization (FISH) alone and in combination with the direct viable count method (DVC) to determine if plate counts underestimated total and viable Salmonella abundances and if the Salmonella cell viability changed after passing through the treatment systems. In most cases, total and viable cell abundances in treatment system effluents were several orders of magnitude higher than cultured cell abundances. Our results indicate that the culture-based method underestimated viable concentrations of the model pathogen, S. choleraesuis. Salmonella cell viability decreased in effluents during the summer but increased during the winter. Using a culture-based enumeration method alone to determine removal efficiencies of bacterial indicators and pathogens for wastewater treatment systems may result in artificially high estimates of effective treatment.

scholarly journals Domestic wells have high probability of pumping septic tank leachate

2012 ◽  
Vol 16 (8) ◽  
pp. 2453-2467 ◽  
Author(s):  
J. E. Bremer ◽  
T. Harter
Keyword(s):  
Wastewater Treatment ◽  
Groundwater Flow ◽  
Mass Balance ◽  
High Probability ◽  
Source Area ◽  
Septic Tank ◽  
Septic Systems ◽  
Septic System ◽  
Onsite Wastewater ◽  
Onsite Wastewater Treatment

Abstract. Onsite wastewater treatment systems are common in rural and semi-rural areas around the world; in the US, about 25–30% of households are served by a septic (onsite) wastewater treatment system, and many property owners also operate their own domestic well nearby. Site-specific conditions and local groundwater flow are often ignored when installing septic systems and wells. In areas with small lots (thus high spatial septic system densities), shallow domestic wells are prone to contamination by septic system leachate. Mass balance approaches have been used to determine a maximum septic system density that would prevent contamination of groundwater resources. In this study, a source area model based on detailed groundwater flow and transport modeling is applied for a stochastic analysis of domestic well contamination by septic leachate. Specifically, we determine the probability that a source area overlaps with a septic system drainfield as a function of aquifer properties, septic system density and drainfield size. We show that high spatial septic system density poses a high probability of pumping septic system leachate. The hydraulic conductivity of the aquifer has a strong influence on the intersection probability. We find that mass balance calculations applied on a regional scale underestimate the contamination risk of individual drinking water wells by septic systems. This is particularly relevant for contaminants released at high concentrations, for substances that experience limited attenuation, and those that are harmful even at low concentrations (e.g., pathogens).

Efficiency of Subsurface Sewage Disposal Systems in Removal of Contaminants From Domestic Sewage

1976 ◽  
Vol 11 (1) ◽  
pp. 1-18
Author(s):  
M. Brandes
Keyword(s):  
Ground Water ◽  
Faecal Coliform ◽  
Septic Tank ◽  
Considerable Part ◽  
Radioactive Phosphorus ◽  
Clayey Silt ◽  
Septic Tank Effluent ◽  
Receiving Waters ◽  
Removal Of Contaminants ◽  
St Lawrence River

Abstract In order to determine the efficiency of subsurface disposal systems in removal of contaminants, fifteen systems located on three lakes and on the St. Lawrence River in Ontario, were under study for about two years. Tritium (3H) , radioactive phosphorus (32p) and fluorescein were used for tracing the subsurface movement of the septic tank effluent and for determining the time taken by the effluent to reach the receiving waters. It was observed that a considerable part (89 to 98%) of the phosphorus from the effluent was fixed in the soil when the soil contained more than 67% silt and clay. When clayey silt was the filtering medium the concentration of the phosphorus in the ground water dropped to a level of less than 0.2 mg/l (as P) in a distance of 17 meters from the disposal systems. A satisfactory removal of faecal coliform organisms by the same uniform undisturbed clayey silt was also observed. The removal of phosphorus and of faecal coliform organisms by disposal systems built on sandy fill was less efficient. The concentration of nitrates, free ammonia and chlorides in the ground water close to receiving waters was lower than concentrations permissible in public surface water supplies.

scholarly journals Treatment of wastewater from service areas at motorways

2016 ◽  
Vol 42 (4) ◽  
pp. 80-89 ◽  
Author(s):  
Małgorzata Makowska ◽  
Jakub Mazurkiewicz
Keyword(s):  
Wastewater Treatment ◽  
Water Use ◽  
Septic Tank ◽  
Effluent Quality ◽  
Aeration System ◽  
Service Areas ◽  
Design Values ◽  
Reed Bed ◽  
Wastewater Treatment Systems

Abstract This paper deals with wastewater treatment systems placed in motorway service areas (MSAs). In the years 2008-2009 eight of such facilities installed on the stretch of the A2 motorway between Poznań and Nowy Tomyśl were examined and analyzed. The system consists of a septic tank, a submerged aerated biofilter and an outflow filter. The volume of traffic on the highway was analyzed, the amount of water use was measured and peak factors were calculated. On this basis it was concluded that the inflows to the wastewater treatment systems in many cases exceeded the nominal design values. Based on the analysis of effluent quality it was found that the effects of plant operation in large part did not meet the requirements. It was found that the bioreactor aeration system and the design of the suspension separator (outflow filter) should be modified. One of the solutions was to use the soil-reed bed for wastewater treatment. The treatment of wastewater from the MSAs is a task that must take into account the unusual character of these facilities and the atypical quality of the effluent.

Factors affecting the performance and risks to human health of on-site wastewater treatment systems

2010 ◽  
Vol 62 (7) ◽  
pp. 1499-1509 ◽  
Author(s):  
K. J. Levett ◽  
J. L. Vanderzalm ◽  
D. W. Page ◽  
P. J. Dillon
Keyword(s):  
Drinking Water ◽  
Wastewater Treatment ◽  
Human Health ◽  
Irrigation Management ◽  
South Australia ◽  
System Size ◽  
Nutrient Concentrations ◽  
Septic Systems ◽  
Septic Tanks ◽  
Wastewater Treatment Systems

Aerobic wastewater treatment systems (aerobic systems) are the preferred choice in a region overlying a karstic aquifer used for drinking water supplies, as they are thought to provide better protection to groundwater and human health than standard septic systems. However, aerobic systems in operation do not always perform to design standard; while this is often blamed on lack of maintenance, few studies have investigated the link directly. This study investigates the performance of domestic on-site wastewater treatment systems in South Australia, and compares effluent quality to maintenance records. Effluent from 29 septic tanks and 31 aerobic systems was analysed for nutrients, physico-chemical parameters and microbiological indicators. Aerobic systems generally provided greater treatment than septic tanks, yet most aerobic systems did not meet regulatory guidelines with high levels of indicator bacteria in 71% of samples. The effect of system size, number of household occupants and maintenance on aerobic system treatment performance was analysed: chlorine levels were positively correlated with time of last service, and nutrient concentrations were positively correlated with the number of occupants. A microbial risk assessment revealed the observed irrigation practices to be high risk; and sufficient residence time in the aquifer cannot be guaranteed for protection of groundwater used for drinking. Additional preventive measures such as irrigation management or post treatment of drinking water supply (such as UV disinfection) are required to meet public health targets.

Bacteriological Pollution in the Drinking-water of Jordan

1976 ◽  
Vol 3 (3) ◽  
pp. 197-199
Author(s):  
Asem Shehabi
Keyword(s):  
Drinking Water ◽  
Ground Water ◽  
Faecal Coliform ◽  
Coliform Bacteria ◽  
Water Supplies ◽  
Chlorinated Drinking Water

The present bacteriological pollution of chlorinated drinking-water supplies in many regions of Jordan gives cause for considerable alarm, especially as it has been ascertained in the work described in this paper that faecal coliform Bacteria have already polluted 37% of the underground wells in the Amman–Zarqa area. Intensive efforts should be launched in order to prevent further pollution of ground-water in Jordan.

Nitrogen and carbon dynamics beneath on-site wastewater treatment systems in Pitt County, North Carolina

2013 ◽  
Vol 69 (3) ◽  
pp. 663-671 ◽  
Author(s):  
Katie L. Del Rosario ◽  
Charles P. Humphrey ◽  
Siddhartha Mitra ◽  
Michael A. O'Driscoll
Keyword(s):  
North Carolina ◽  
Wastewater Treatment ◽  
Surface Water ◽  
Significant Negative Correlation ◽  
Separation Distance ◽  
Septic Tank ◽  
Sample Collection ◽  
Nutrient Analysis ◽  
Total Dissolved Nitrogen ◽  
Wastewater Treatment Systems

On-site wastewater treatment systems (OWS) are a potentially significant non-point source of nutrients to groundwater and surface waters, and are extensively used in coastal North Carolina. The goal of this study was to determine the treatment efficiency of four OWS in reducing total dissolved nitrogen (TDN) and dissolved organic carbon (DOC) concentrations before discharge to groundwater and/or adjacent surface water. Piezometers were installed for groundwater sample collection and nutrient analysis at four separate residences that use OWS. Septic tank effluent, groundwater, and surface water samples (from an adjacent stream) were collected four times during 2012 for TDN and DOC analysis and pH, temperature, electrical conductivity, and dissolved oxygen measurements. Treatment efficiencies from the tank to the groundwater beneath the drainfields ranged from 33 to 95% for TDN and 45 to 82% for DOC, although dilution accounted for most of the concentration reductions. There was a significant positive correlation between nitrate concentration and separation distance from trench bottom to water table and a significant negative correlation between DOC concentration and separation distance. The TDN and DOC transport (>15 m) from two OWS with groundwater saturated drainfield trenches was significant.

scholarly journals The Life Cycle Environmental Performance of On-Site or Decentralised Wastewater Treatment Systems for Domestic Homes

Water ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 2542
Author(s):  
John Gallagher ◽  
Laurence W. Gill
Keyword(s):  
Wastewater Treatment ◽  
Life Cycle ◽  
Environmental Impacts ◽  
Environmental Sustainability ◽  
Environmental Performance ◽  
System Level ◽  
Septic Tank ◽  
Soil Percolation ◽  
Trench Area ◽  
Wastewater Treatment Systems

There is little knowledge regarding the environmental sustainability of domestic on-site or decentralised wastewater treatment systems (DWWTS). This study evaluated six unique life cycle environmental impacts for different DWTTS configurations of five conventional septic tank systems, four packaged treatment units, and a willow evapotranspiration system. Similar freshwater eutrophication (FE), dissipated water (DW), and mineral and metal (MM), burdens were noted between the packaged and conventional system configurations, with the packaged systems demonstrating significantly higher impacts of between 18% and 56% for climate change (CC), marine eutrophication (ME), and fossils (F). At a system level, higher impacts were observed in systems requiring (i) three vs. two engineered treatment stages, (ii) a larger soil percolation trench area, and (iii) pumping of effluent. The evapotranspiration system presented the smallest total environmental impacts (3.0–10.8 lower), with net benefits for FE, ME, and MM identified due to the biomass (wood) production offsetting these burdens. Further analysis highlighted the sensitivity of results to biomass yield, operational demands (desludging or pumping energy demands), and embodied materials, with less significant impacts for replacing mechanical components, i.e., pumps. The findings highlighted the variation in environmental performance of different DWTTS configurations and indicated opportunities for design improvements to reduce their life cycle impacts.

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