Septic Systems

Adegoke, Anthony A.; Stenström, Thor-Axel

doi:10.14321/waterpathogens.59

Cited by 18 publications

(23 citation statements)

References 33 publications

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“…Authors variously suggest a treatment effectiveness of 0-2 log removal of pathogens, with several suggesting 0.5 log removal (Feachem et al, 1983;Stenström et al, 2011). As such, septic tanks alone are not considered to be a significant barrier against pathogen transmission, and it is recommended that they discharge to a properly designed and sited soil absorption system (Adegoke and Stenstrom, 2019). Adegoke and Stenstrom (2019) research also notes that treatment effectiveness assumes that the septic tank is operating as it is designed to, that it has at least two chambers and that it is regularly emptied of sludge to ensure adequate hydraulic retention time.…”

Section: Contaminationmentioning

confidence: 99%

Costs, Climate and Contamination: Three Drivers for Citywide Sanitation Investment Decisions

Mills

Willetts

Evans

et al. 2020

Front. Environ. Sci.

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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.

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Section: Contaminationmentioning

confidence: 99%

Costs, Climate and Contamination: Three Drivers for Citywide Sanitation Investment Decisions

Mills

Willetts

Evans

et al. 2020

Front. Environ. Sci.

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“…Because no centralized sanitation infrastructure exists in Jacó, information about the current on-site sanitation infrastructure was collected in 2014 and 2019 via the aforementioned interviews, as well as local government records for the small-scale commercial wastewater treatment plants in the watershed . The sanitation technologies’ pathogen LRVs were based on the literature (Table S12), ,− and the overall pathogen LRV for each sanitation scenario was calculated by summing the LRVs for all the technologies in the scenario. Pathogen LRVs are the same for each sanitation scenario regardless of population.…”

Section: Methodsmentioning

confidence: 99%

Holistically Managing Pathogens and Nutrients in Urbanizing Tropical Towns: Can Sanitation Technologies Create Safer Conditions for Beach Recreation?

et al. 2021

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Rapidly urbanizing coastal communities are prone to overpopulation and unrestrained growth that result in pathogen and nutrient emissions, which impair beach water quality and jeopardize human and environmental health. Decision makers face complex, context-dependent choices when selecting sanitation technologies with varying abilities to remove pathogens and nutrients. The goal of this study was to identify context-appropriate sanitation solutions that manage pathogens and nutrients to ensure safe beach swimming conditions in an urbanizing coastal town that relies on tourism. Quantitative microbial risk assessment was utilized to determine the pathogen log10 reduction values (LRVs) required for safe swimming. A lack of consensus in the literature about an aggregation parameter in the norovirus dose–response model resulted in predicted LRVs that differed by as much as 3 orders of magnitude. Local experts identified nine context-appropriate infrastructure scenarios, and their ability to reduce pathogen and nutrient loadings was modeled. The model showed that spatially targeted sanitation infrastructure scenarios could effectively meet LRV targets. Seasonal increases in population were predicted to greatly impact pathogen and nutrient loadings. Top-performing scenarios that managed both pathogens and nutrients included centralized treatment with disinfection and integrated resource recovery. Future research is needed to understand the scenarios’ sociocultural feasibility and costs.

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“…Given the initial concentration of total coliforms (3.3 × 10 5 CFU/mL) and their dose response to LP UV light, REDs at these flow rates were more than high enough to meet the WHO irrigation guidelines for fecal coliforms of 1000 CFU/mL for WFMF-treated wastewater [29,37]. Microorganisms of concern for septic tanks, for which outbreaks have been associated with poor septic tank performance, include norovirus, rotavirus, hepatitis A, Salmonella spp., and E. coli [58]. Table 3 estimates the LP UV log-inactivation of these pathogens from these doses given this MS2 RED.…”

Section: Flow-through Uv Reactor Disinfection Efficiencymentioning

confidence: 99%

“…These RED were also high enough for inactivation of Giardia spp. and Cryptosporidium spp., which are not linked to septic tank discharge, but require only 22 mJ/cm 2 for 4-log reduction [37,58]. Similarly, an LP UV dose of 40-50 mJ/cm 2 would completely inactivate SARS-CoV-2, the virus responsible for COVID-19, which requires only 3.7 mJ/cm 2 for 3-log reduction in aqueous solutions.…”

Section: Flow-through Uv Reactor Disinfection Efficiencymentioning

confidence: 99%

Woven-Fiber Microfiltration (WFMF) and Ultraviolet Light Emitting Diodes (UV LEDs) for Treating Wastewater and Septic Tank Effluent

Beck

Suwan

Rathnayeke

et al. 2021

Water

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Decentralized wastewater treatment systems enable wastewater to be treated at the source for cleaner discharge into the environment, protecting public health while allowing for reuse for agricultural and other purposes. This study, conducted in Thailand, investigated a decentralized wastewater treatment system incorporating a physical and photochemical process. Domestic wastewater from a university campus and conventional septic tank effluent from a small community were filtered through a woven-fiber microfiltration (WFMF) membrane as pretreatment for ultraviolet (UV) disinfection. In domestic wastewater, WFMF reduced TSS (by 79.8%), turbidity (76.5%), COD (38.5%), and NO3 (41.4%), meeting Thailand irrigation standards for every parameter except BOD. In septic tank effluent, it did not meet Thailand irrigation standards, but reduced TSS (by 77.9%), COD (37.6%), and TKN (13.5%). Bacteria (total coliform and Escherichia coli) and viruses (MS2 bacteriophage) passing through the membrane were disinfected by flow-through UV reactors containing either a low-pressure mercury lamp or light-emitting diodes (LEDs) emitting an average peak wavelength of 276 nm. Despite challenging and variable water quality conditions (2% < UVT < 88%), disinfection was predictable across water types and flow rates for both UV sources using combined variable modeling, which enabled us to estimate log inactivation of other microorganisms. Following UV disinfection, wastewater quality met the WHO standards for unrestricted irrigation.

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Septic Systems

Cited by 18 publications

References 33 publications

Costs, Climate and Contamination: Three Drivers for Citywide Sanitation Investment Decisions

Costs, Climate and Contamination: Three Drivers for Citywide Sanitation Investment Decisions

Holistically Managing Pathogens and Nutrients in Urbanizing Tropical Towns: Can Sanitation Technologies Create Safer Conditions for Beach Recreation?

Woven-Fiber Microfiltration (WFMF) and Ultraviolet Light Emitting Diodes (UV LEDs) for Treating Wastewater and Septic Tank Effluent

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