<i>In situ</i> treatment technologies for pit latrines to mitigate groundwater contamination by fecal pathogens: a review of recent technical advances

Saxena, Shray; Den, Walter

doi:10.2166/washdev.2021.184

Cited by 13 publications

(5 citation statements)

References 46 publications

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“…This study aimed to determine the alkali dosage and contact time required for virus inactivation in faecal sludge and wastewater with high solid loading. Since alkaline treatment is widely used for sludge treatment, we identified several reviews aimed at evaluating the pathogen inactivation efficacy of alkaline treatment (e.g., (57)(58)(59)). However, previous reviews have provided little quantitative data on viruses and bacteriophage.…”

Section: Discussionmentioning

confidence: 99%

Estimation of alkali dosage and contact time for treating human excreta containing viruses as an emergency response: a systematic review

Oishi,

Sano

2023

Front. Public Health

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Water, sanitation, and hygiene provisions are essential during emergencies to prevent infectious disease outbreaks caused by improper human excreta management in settlements for people affected by natural disasters and conflicts. Human excreta disinfection is required when long-term containment in latrines is not feasible on-site. Alkali additives, including lime, are effective disinfectants for wastewater and faecal sludge containing large amounts of solid and dissolved organic matter. The aim of this study was to determine the minimum dose and contact time of alkali additives for treating virus-containing human excreta in emergency situations. We used literature data collected by searching Google Scholar and Web of Science. The date of the last search for each study was 31th May 2023. Only peer-reviewed articles that included disinfection practices in combination with quantitative data for the physicochemical data of a matrix and viral decay were selected for data extraction. Two reviewers independently collected data from each study. We extracted datasets from 14 studies that reported quantitative information about their disinfection tests, including viral decay over time, matrix types, and physicochemical properties. Three machine learning algorithms were applied to the collected dataset to determine the time required to achieve specified levels of virus inactivation under different environmental conditions. The best model was used to estimate the contact time to achieve a 3-log10 inactivation of RNA virus in wastewater and faeces. The most important variables for predicting the contact time were pH, temperature, and virus type. The estimated contact time for 3 log inactivation of RNA virus was <2 h at pH 12, which was achieved by adding 1.8 and 3.1% slaked lime to wastewater and faeces, respectively. The contact time decreased exponentially with the pH of the sludge and wastewater. In contrast, the pH of the sludge and wastewater increased linearly with the slaked lime dosage. Lime treatment is a promising measure where long-term containment in latrine is not feasible in densely populated areas, as 1 day is sufficient to inactivate viruses. The relationship we have identified between required contact time and lime dosage is useful for practitioners in determining appropriate treatment conditions of human waste.

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Section: Discussionmentioning

confidence: 99%

Estimation of alkali dosage and contact time for treating human excreta containing viruses as an emergency response: a systematic review

Oishi,

Sano

2023

Front. Public Health

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“…Pit-latrines are assumed to be not being emptied, based on estimates that approximately 1% of pit-latrines are undergoing emptying in Malawi (Hinton et al, 2024). Similarly, pit-latrines were assumed to be unlined, around 10-15% of pit-latrines are estimated to be lined nationally (Chiposa et al, 2017, Hinton et al, 2024, where lining is used, interwoven logs and bamboo sticks are commonplace and can provide limited capacity to minimise contamination (Namwebe et al, n.d;Saxena and Den, 2022). Assumptions regarding lining and emptying of pit-latrines are therefore deemed to be justified.…”

Section: Methodological Limitationsmentioning

confidence: 99%

Spatial model of groundwater contamination risks from pit-latrines under multiple sanitation scenarios in a low-income country

Hinton,

Kalin,

Kanjaye

et al. 2024

Preprint

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Pit-latrines are central to achieving UN Sustainable Development Goal 6 (SDG6) of ensuring “clean water and sanitation for all”. Unless safely managed, pit-latrines result in groundwater contamination, which increases morbidity and mortality. Despite this, there have been no long-term spatial projections of future pit-latrine contamination risks. National survey data of over 100,000 water-points and 260,000 pit-latrines in Malawi was used to generate a novel, high-resolution model of pit-latrines from 2020-2070 under five population and three stakeholder informed sanitation policy scenarios. The ‘business as usual’ model predicts a three-fold increase in the number of current water-points at risk of microbial pit-latrine contamination between 2020-2070, with a seven-fold increase in number at the highest risk of contamination. Current nitrogen loading into pit-latrines is comparable to national fertiliser application. The model predicts 8.2 mega-tonnes of faecal nitrogen will be disposed of into subsequently abandoned pit-latrines between 2020-2070. Guided intervention is necessary to prevent SDG6’s push for sanitation undermining its goal of clean water.

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“…The result showed that the turbidity of all the well water sampled is not within the permissible limits of 5 NTU except in January 2021 (SON, 2007;WHO, 2014;. The measurement of pH is one of the most frequently used tests in water chemistry (Saxena, 2021). In Figure 5, the mean seasonal pH variation was recorded to be highest in September during rainy season) at 7.5 and lowest in January during dry season at 7.3.…”

Section: ) Statistical Analysesmentioning

confidence: 96%

“…Studies also showed that shallow wells, being a relatively more costeffective and accessible source of water for an average household in developing countries, including Nigeria are frequently used without regard for their potability. This is attributed as the consumption of untreated water source, thus, a cause of waterborne diseases (Ale et al, 2015;Malla et al, 2018;Ogeleka & Emegha, 2021;Saxena, 2021). Fagerli et al (2017); Pal et al (2018); Adnani et al (2020); Bastaraud et al (2020) and Afolabi et al (2021) strongly viewed that the prevalence of gastrointestinal diseases (such as cholera, diarrhoea, dysentery typhoid and viral hepatitis) is caused by consumption of contaminated water.…”

Section: Introductionmentioning

confidence: 99%

Physico-chemical and bacteriological assessments of shallow well water samples during the dry and rainy seasons

Ayeni,

Oyegoke,

Ndububa

et al. 2023

Nig. J. Technol. Dev.

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There is need to study the impact of seasonal variations on well water quality especially in Ado – Ekiti metropolis as this will assist in creating awareness on groundwater quality for domestic consumption. The quality of groundwater obtained during dry and rainy seasons from 60 privately utilized hand-dug closed wells in Ado Ekiti metropolis were assessed. Physicochemical and bacteriological investigations were carried out according to required standards. The temperature, colour, turbidity, pH, total solids, chlorides, sulphate, calcium, magnesium, nitrate, and iron, which are physico-chemical parameters of the well water samples ranged from 24.7 to 25.6 °C, 4.1 to 7.3 HU, 3.7 to 6.9 NTU, 7.3 to 7.5, 95.7 to 211.1 mg/L, 38.6 to 74.6 mg/L, 34.3 to 64.9 mg/L, 24.3 to 49.4 mg/L, 48.1 to 89.0 mg/L, 0.4 to 0.8 mg/L and 0.05 to 1.0 mg/L respectively. Despite the fact that the parameters were within the acceptable ranges, bacteriological studies showed the presence of E. coli (ranged from 19.5 to 81.6 CFU) throughout the seasons, thus, individuals who rely on groundwater for their health are exposed to disease-causing organisms. Deductions from the correlation matrix equally, demonstrated the relative dependence of the parameters on one another as they variate according to the change in weather. Mostly during the rainy seasons, higher concentrations of the physicochemical and bacteriological parameters were observed than during the dry seasons, proving that the rainy seasons aid anthropogenic activities from the surface to transmit dissolved harmful waste materials to the subsurface which eventually finds its paths into the groundwater. Improper disposal of faeces, faulty soak-pits, latrines, dumpsites and burial grounds are part of the factors that contribute to bacteriological pollutants in the groundwater source.

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In situ treatment technologies for pit latrines to mitigate groundwater contamination by fecal pathogens: a review of recent technical advances

Cited by 13 publications

References 46 publications

Estimation of alkali dosage and contact time for treating human excreta containing viruses as an emergency response: a systematic review

Estimation of alkali dosage and contact time for treating human excreta containing viruses as an emergency response: a systematic review

Spatial model of groundwater contamination risks from pit-latrines under multiple sanitation scenarios in a low-income country

Physico-chemical and bacteriological assessments of shallow well water samples during the dry and rainy seasons

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