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Keeping disease-causing microorganisms out of groundwater used for drinking water supplies is important to protect human health. This 7-page fact sheet reports the sources of bacteria and protozoa in wastewater, discusses diseases associated with drinking water contaminated with wastewater, and then details their fate in septic systems. Written by...
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... protozoa called microsporidia, 2 such as Encephalitozoon sp., are also a health concern in septic systems. Table 2 includes a few of the protozoa present in wastewater and the diseases and symptoms they can cause in humans. ...Similar publications
Provision of safe drinking water (DW) is one of the major requisites for human health, related to four Sustainable Development Goals (SDGs) of the United Nation 2030 Agenda: SDGs 3 (Good health), 6 (Clean water and sanitation), 11 (Sustainable cities) and 12 (Responsible production and consumption). However, this is hindered by the presence, especi...
Citations
... If your septic system is not prepared for an oncoming storm or if it is damaged during the storm, wastes can back up into your home. This can also increase the risk of pollutants and harmful germs from wastewater entering the environment (Lusk, Toor, and Obreza 2014;Lusk, Toor, and Obreza 2011). The purpose of this guide is to provide tips for how to check, maintain, and use your septic system in the days leading up to a hurricane and immediately after any associated flooding. ...
The purpose of this guide is to provide tips for how to check, maintain, and use your septic system in the days leading up to a hurricane and immediately after any associated flooding. This guide is intended for residents who have a residential septic system connected to their home. Written by Mary G. Lusk, and published by the UF/IFAS Department of Soil, Water, and Ecosystem Sciences, October 2024.
... Potential pollutants from septic systems include nutrients (nitrogen and phosphorus), which, in excess, can cause algal blooms and fish kills in water resources; pathogens; and organic chemicals. Other resources provide a full discussion of the sources, fate, and removal mechanisms in septic systems for nitrogen, phosphorus, bacteria and protozoa, viruses, and organic chemicals Lusk, Toor, and Obreza 2011b;Lusk, Toor, and Obreza 2014;Lusk, Toor, and Obreza 2011a;Toor, Lusk, and Obreza 2011c). Figure 2 provides a brief summary. ...
The purpose of this publication is to explain how septic systems may be affected by floods from hurricanes and other storms and/or by climate change (sea-level rise) that raises the level of the groundwater under septic system soils. Written by Mary G. Lusk, and published by the UF/IFAS Department of Agricultural and Biological Engineering, November 2023.
... Thus, ABR use is an appropriate option for developing countries [13], where it acts as a replacement for septic tank use for onsite domestic wastewater treatment. Septic tanks pose higher potential risks because of their inability to absorb hydraulic shocks, their inferior treatment of sludge, and resultant underground pollution of surface water and the water table [14][15][16]. ...
The present study explored the efficiency of a four-chambered anaerobic baffled reactor (ABR) as a cost-effective and sustainable method of organic pollutant and pathogen removal from domestic wastewater, under a range of environmental conditions. An ABR with a circular additional filter at the outlet pipe was constructed to treat wastewater from a residential colony of 108 households with an average inflow of 110 m³/day and a nominal hydraulic retention time (HRT) of 20 h. Analysis of the chemical oxygen demand (COD), total nitrogen, sulfate and phosphate load, and total coliform removal for 2 years of operation, 2015 and 2017, showed a COD of 46%, sulfate load of 28%, phosphate load of 51% and total nitrogen of 28% for 2015, compared to a COD of 48%, sulfate load of 44%, phosphate load of 58% and total nitrogen of 31% for 2017. The lack of a significant effect of sludge removal suggested a stable process. The overall efficiency of the ABR increased in the summer, including for pathogen removal, which was significantly higher during the summer months of both years. Overall, the ABR was found to be able to consistently treat primary wastewater, although tertiary effluent treatment was still required before water reuse or final discharge.
... Low levels of access to sanitation are associated with an increased prevalence of disease, particularly diseases that continue to inflict a heavy burden in low-income settings, including diarrhea, soil-transmitted helminth infections, trachoma, cholera and schistosomiasis (Speich et al., 2016;Freeman et al., 2017). In locations with high prevalence rates of infectious disease, pathogen concentrations discharged to sanitation systems or into the environment are correspondingly high, particularly during outbreaks (Lusk et al., 2014). The risk to human health is not only driven by pathogen occurrence but also by their persistence in the environment, the presence of vectors or intermediate hosts, and the level of infectivity of individual pathogens (Aw, 2018). ...
... The risk to human health is not only driven by pathogen occurrence but also by their persistence in the environment, the presence of vectors or intermediate hosts, and the level of infectivity of individual pathogens (Aw, 2018). In addition, several diseases such as pathogenic E. Coli, salmonellae, and shigella have low infectious doses (e.g., can cause infection in humans with fewer than 20 organisms), whilst they are present in much higher concentrations in wastewater (e.g., more than 10,000 organisms/L) (Lusk et al., 2014). Pathogens that are discharged across the urban environment can be transmitted through multiple exposure pathways, including through contact with drain water, surface water or flood water during activities such as playing, washing and bathing, and through food pathways (Wang et al., 2017). ...
Significant progress is needed, in both large cities and small towns, to meet the ambitious targets set at international and national levels relating to universal access to safely managed sanitation. There has been increased recognition in the urban sanitation sector that in rapidly growing cities, there is unlikely to be a single centralized sanitation solution which can effectively deliver services to all demographics, and that heterogeneous approaches to urban sanitation are required. At the same time, due to competing investment priorities, there is a greater focus on the need for sanitation investments to address multiple objectives. However, calls for more informed sanitation planning and a more dynamic and disaggregated approach to the delivery and management of sanitation services have had limited impacts. This is in part due to the complexity of the drivers for sanitation investment, and the difficulties involved in identifying and addressing these multiple, often conflicting, goals. This paper examines three potential drivers of citywide sanitation decision-making – public health, sustainability and economic performance – via the three proxies of contamination, climate change and costs. It examines the importance of each driver and proxies, how they are considered in investment decisions, the current state of knowledge about them, and priority aspects to be included in decisions. At present, while public health is a common driver for improving sanitation, there are significant gaps in our understanding of fecal contamination spread and exposure, and how to select sanitation solutions which can best address them. Climate change is sometimes seen as a low priority for the sanitation sector given the immediacy and scale of existing challenges and the uncertainty of future climate predictions. However, potential risks are significant, and uninformed decisions may result in greater costs and increased inequalities. Cost data are sparse and unreliable, and it is challenging to build robust cost-effectiveness analyses. Yet these are needed to compare citywide options based on least-cost over their full life cycle. This paper provides insights into how existing evidence on contamination, climate change and costs can inform decisions on sanitation investments and help chart a sustainable way forward for achieving citywide services.
... Septic tanks are not always designed and sited correctly and often fail (US EPA, 2002;Day, 2004). Failure of STS due to physical damage and poor maintenance increases the risk of contaminants entering stream waters, with several studies linking disease outbreaks with septic tank density and discharges (Borchardt et al., 2003;Katz et al., 2010 andLusk et al., 2011). The potential enrichment factor of STE contaminant concentrations relative to those in stream waters is large for some contaminants, notably, ammonia (NH 4 ), dissolved phosphorus (DP), Escherichia coli (E. ...
Discharges from the widely distributed small point sources of pollutants such as septic tanks contribute to microbial and nutrient loading of streams and can pose risks to human health and stream ecology, especially during periods of ecological sensitivity. Here we present the first comprehensive data on the compositional variability of septic tank effluents (STE) as a potential source of water pollution during different seasons and the associated links to their influence on stream waters. To determine STE parameters and nutrient variations, the biological and physicochemical properties of effluents sampled quarterly from 12 septic tank systems were investigated with concurrent analyses of upstream and downstream receiving waters. The study revealed that during the warmer dryer months of spring and summer, effluents were similar in composition, as were the colder wetter months of autumn and winter. However, spring/summer effluents differed significantly (P < 0.05) from autumn/winter for concentrations of biological oxygen demand (BOD), arsenic, barium (Ba), cobalt, chromium, manganese, strontium (Sr), titanium, tungsten (W) and zinc (Zn). With the exception of BOD, Ba and Sr which were greater in summer and spring, the concentrations of these parameters were greater in winter. Receiving stream waters also showed significant seasonal variation (P ≤ 0.05) in alkalinity, BOD, dissolved organic carbon, sulphate, sulphur, lithium, W, Zn and Escherichia coli abundance. There was a clear significant influence of STE on downstream waters relative to upstream from the source (P < 0.05) for total suspended solids, total particulate P and N, ammonium-N, coliforms and E. coli. The findings of this study found seasonal variation in STE and place effluent discharges as a factor affecting adjacent stream quality and call for appropriate measures to reduce or redirect STE discharges away from water courses.
... The pathogens present in human faeces comprise bacteria, virus, parasitic protozoa and helminths ); according to the USEPA, in just one gram it is possible to find up to 1 trillion different bacteria, as Lusk et al. (2011) quoted. Since it is not feasible to measure all of them, specific indicator bacteria, such as faecal coliforms and faecal streptococci, have been selected to reflect the presence of human pathogens (Lusk et al. 2011). ...
... The pathogens present in human faeces comprise bacteria, virus, parasitic protozoa and helminths ); according to the USEPA, in just one gram it is possible to find up to 1 trillion different bacteria, as Lusk et al. (2011) quoted. Since it is not feasible to measure all of them, specific indicator bacteria, such as faecal coliforms and faecal streptococci, have been selected to reflect the presence of human pathogens (Lusk et al. 2011). ...
The septic tank is considered the most common onsite wastewater treatment technology; although not prioritized by many sanitation agencies, septic tank installations will continue to serve the ever growing peri-urban areas in developing countries as well as isolated small communities all over the world. As a consequence, the generation of septic sludge will continue increasing for years to come. On the other hand, the lack of knowledge in septic sludge management has cause serious pollution to terrestrial and aquatic environments.
The use of VFCW for septage treatment has shown promising results since its first implementation and is of potential interest for developing countries, especially with tropical climates. Nonetheless, further research work in operational strategies and economic post treatment alternatives should be addressed in order to obtain acceptable effluent qualities according to the final disposal and agricultural reuse regulations
In this research, it was evaluated the performance of two different operational strategies in a full-scale sludge drying reed bed system, consisting of two VFCW units (W1 and W2) planted with Cynodon dactylon Pers, for the treatment and post treatment of septic tank sludge. For this reason, it was evaluated the removal of COD, BOD5, TKN, NH4+, TS, TVS and E. coli from the liquid fraction; as well as, the pathogenic contamination of the accumulated sludge layer in terms of Total coliforms (NMP/gTS), Escherichia coli (NMP/gTS) and viable Ascaris Lumbricoides eggs (viable egg/g).
The two operational strategies (OS) were (i) OS2: after sludge application, the percolate from W1 was retained for 6 days inside this unit, after which it was sent to W2 for post-treatment, without any retention in this unit; (ii) OS3: the percolate from W1 was retained for 6 days inside this unit for initial treatment, after which it was sent to W2 for post-treatment, remaining there for another period of 6 days.
The OS2 achieved global removal efficiencies (%), for the percolated fraction, of 89, 98, 78, 82, 56 and 73 for COD, BOD5, NH4+, TKN, TS and TVS respectively, as well as 2.4 log removal units of E. coli. While the OS3 achieved global removal efficiencies (%) for the percolated fraction of 94, 90, 68, 87, 68 and 82 for COD, BOD5, NH4+, TKN, TS and TVS respectively, as well as 4.2 log removal units of E. coli. According to the statistical analysis performed, the OS3 improved significantly the removal efficiencies of COD, TS, TVS and E. coli.
It was concluded that OS3 is not worth it for peri-urban or urban regions where the land area is very expensive or not available at all. Nonetheless, for small remote communities this could be a worthwhile option in order to reuse the percolated effluent in restricted irrigation.
Regarding the accumulated sludge layer, its pathogenic quality was not good enough during the operational stage, considerable concentrations of E. coli and viable eggs of Ascaris lumbricoides were present; therefore, it would require a treatment for reuse in agriculture or as soil conditioning.
