128 results found
Sione L, Bastable A, Ampilan A, et al., 2023, Lessons learned from a Tiger Worm Toilet implementation project in Sierra Leone, Journal of Water, Sanitation and Hygiene for Development, Vol: 13, Pages: 604-609, ISSN: 2043-9083
This paper discusses the implementation of Tiger Worm Toilets (TWTs) as a sustainable alternative to pit latrines in areas with challenging environmental conditions. The study was carried out in Koinadugu, Sierra Leone, where TWTs were installed in 200 households, providing safe sanitation for approximately 1,200 individuals within a 17-month period. The study reveals that TWTs offer several benefits over traditional pit latrines, including higher cost efficiency. Despite some setbacks, TWTs have been well-received by the local communities, resulting in a significant reduction in open defaecation in areas where latrines are not viable. The study presents areas of further research and concludes with recommendations for future TWT designs based on the lessons learned.
Koulouri ME, Templeton MR, Fowler GD, 2023, Source separation of human excreta: effect on resource recovery via pyrolysis, Journal of Environmental Management, Vol: 338, Pages: 1-10, ISSN: 0301-4797
More people globally are now using on-site sanitation technologies than sewered connections. The management of faecal sludge generated by on-site facilities is still challenging and requires an understanding of all sanitation service chain components and their interactions; from source conditions to treatment and resource recovery. This study aimed to improve the current lack of knowledge regarding these interactions, by establishing a quantifiable relationship between human excreta source separation and resource recovery via pyrolysis. The effects of source separation of faeces and urine on biochar quality were investigated for different pyrolysis temperatures (450 °C, 550 °C, 650 °C) and this information was used to assess energy and nutrient recovery. Results quantify the benefits of urine diversion for nitrogen recovery (70% of total N losses during thermal treatment avoided) and show an increase in the liming potential of the produced faecal-based biochars. The quality of produced solid fuels is also improved when source-separated faeces (SSF) are used as a feedstock for pyrolysis, including a 50% increase in char calorific value. On the other hand, biochars from mixed urine and faeces (MUF) are more rich in phosphorus and potassium, and surface morphology investigation indicates higher porosity compared to SSF biochars. The high salinity of MUF biochars should be considered before agricultural applications. For both biochar types (SSF, MUF), the presence of phosphate compounds of high fertiliser value was confirmed by X-ray diffraction analysis, and temperatures around 500 °C are recommended to optimise nutrient and carbon behaviour when pyrolysing human excreta. These findings can be used for the design of circular faecal sludge management systems, linking resource recovery objectives to source conditions, and vice-versa. Ultimately, achieving consistent resource recovery from human excreta can act as an incentive for universal access to safe
Sione L, Templeton MR, Onof C, et al., 2022, Can a citizen science approach to collecting data assist the management of intermittent water supply in low-income and data-scarce settings?, Waterlines, Vol: 41, Pages: 1-19, ISSN: 0262-8104
Intermittent water supplies (IWS) can be both a public health threat and an expensive challenge to address for households, requiring reliance on either costly water storage solutions or alternative water supplies. Despite the fact that IWS are present all over the world, there remains a persistent lack of data on the operation and failures of urban water supply infrastructure in low-income countries. Local government and water utilities tend to be blamed for the poor management of the water supply, and yet there is no established method for reporting or measuring the continuity, reliability, or hours of supply of pipe water delivery. This makes it difficult for water utilities to estimate real economic losses or the investment needed to improve the water supply. Lack of evidence and data on the behaviour of IWS also impedes the development of tailored water management policies, leading to inefficient decision-making from the top down. This paper therefore proposes a method to address the knowledge and data gap on IWS in low-income settings, using citizen science coupled with mobile phone technology to collect data on IWS in a bottom-up approach. The approach was trialled in Kathmandu, Nepal and has since been adopted by the local water supply company.
Ritson JP, Kennedy-Blundell O, Croft J, et al., 2022, High frequency UV-Vis sensors estimate error in riverine dissolved organic carbon load estimates from grab sampling, Environmental Monitoring and Assessment, Vol: 194, Pages: 1-12, ISSN: 0167-6369
High frequency ultraviolet – visible (UV-VIS) sensors offer a way of improving dissolved organic carbon (DOC) load estimates in rivers as they can be calibrated to DOC concentration. This is an improvement on periodic grab sampling, or the use of pumped sampling systems which store samples in-field before collection. We hypothesised that the move to high frequency measurements would increase the load estimate based on grab sampling due to systemic under-sampling of high flows. To test our hypotheses, we calibrated two sensors in contrasting catchments (Exe and Bow Brook, UK) against weekly grab sampled DOC measurements and then created an hourly time series of DOC for the two sites. Taking this measurement as a ‘true’ value of DOC load, we simulated 1,000 grab sampling campaigns at weekly, fortnightly and monthly frequencyto understand the likely distribution of load and error estimates. We also performed an analysis of daily grab samples collected using a pumped storage sampling system with weekly collection. Our results show that: a) grab sampling systemically underestimates DOC loads and gives positively skewed distributions of results, b) this under-estimation and positive skew decreases with increasing sampling frequency, c) commonly used estimates of error in the load value are also systemically lowered by the oversampling of low, stable flows due to their dependence on the variance in the flow-weighted mean concentration, and d) that pumped storage systems may lead to under-estimation of DOC and over estimation of specific ultra50 violet absorbance (SUVA), a proxy for aromaticity, due to biodegradation during storage.
Zhang J, Pitol AK, Braun L, et al., 2022, The efficacy of soap against schistosome cercariae: a systematic review, PLoS Neglected Tropical Diseases, Vol: 16, ISSN: 1935-2727
Background:Schistosomiasis is a parasitic disease that is endemic in 78 countries and affects almost 240 million people worldwide. It has been acknowledged that an integrated approach that goes beyond drug treatment is needed to achieve control and eventual elimination of the disease. Improving hygiene has been encouraged by World Health Organisation, and one aspect of good hygiene is using soap during water-contact activities, such as bathing and doing laundry. This hygiene practice might directly reduce the skin exposure to cercariae at transmission sites. A systematic review was carried out to investigate the efficacy of soap against schistosome cercariae and to identify the knowledge gaps surrounding this topic.Methodology:Six online databases were searched between 5th and 8th July of 2021. Records returned from these databases were screened to remove duplicates, and the remaining records were classified by reading titles, abstracts, and full texts to identify the included studies. The results were categorised into two groups based on two different protective mechanisms of soap (namely, damage to cercariae and protection of skin).Conclusions:Limited research has been conducted on the efficacy of soap against schistosome cercariae and only 11 studies met the criteria to be included in this review. The review demonstrates that soap has the potential of protecting people against schistosome cercariae and there are two protective aspects: (1) soap affects cercariae adversely; (2) soap on the skin prevents cercariae from penetrating the skin, developing into adult worms and producing eggs. Both aspects of protection were influenced by many factors, but the differences in the reported experimental conditions, such as the cercarial endpoint measurement used and the cercaria numbers used per water sample, lead to low comparability between the previous studies. This review indicates that more evidence is needed to inform hygiene advice for people living in schistosomiasi
Sule MN, Mosha J, Soboka TE, et al., 2022, A novel theatre-based behaviour change approach for influencing community uptake of schistosomiasis control measures, Parasites and Vectors, Vol: 15, ISSN: 1756-3305
Background: Appropriate behaviour change with regard to safe water contact practices will facilitate the elimination of schistosomiasis as a public health concern. Various approaches to effecting this change have been trialled in the field but with limited sustainable outcomes. Our case study assessed the effectiveness of a novel theatre-based behaviour change technique (BCT), in combination with cohort awareness raising and capacity training intervention workshops.Methodology: Our study was carried out in Mwanza, Tanzania and Kemise, Ethiopia. We adapted the Risk, Attitude, Norms, Ability, and Self-regulation (RANAS) framework and four phases using a mixed methods approach. Participatory project phase engagement an11 qualitative formative data were used to guide the design of an acceptable, holistic intervention. Initial baseline (BL) data was collected using quantitative questionnaire surveys with 804 participants in Tanzania and 617 in Ethiopia, followed by the theatre-based BCT and capacity training intervention workshops. Post-intervention (PI) survey was carried out after six months, with a participant return rate of 65% in Tanzania and 60% in Ethiopia. Results: The intervention achieved a significant improvement in the knowledge of schistosomiasis transmission being associated with poorly managed sanitation and risky water contact. Participants in Tanzania increased their uptake of preventive chemotherapy (Male: BL:56%; PI:73%, Female: BL:43%; PI:50%). There was a significant increase in the selection of sanitation (Tanzania: BL:13%; PI:21%, Ethiopia: BL:63%; PI:90%), safe water and avoiding/minimising contact with infested waters as prevention methods in Tanzania and Ethiopia. Some of the participants in Tanzania followed on from the study by building their own latrines. Conclusions: This study showed substantial positive behaviour changes in schistosomiasis control can be achieved using theatre-based BCT intervention and disease awareness training. With app
Tetteh JD, Templeton M, Cavanaugh A, et al., 2022, Spatial heterogeneity in drinking water sources in the Greater Accra Metropolitan Area (GAMA), Ghana, Population and Environment, Vol: 44, Pages: 46-76, ISSN: 0199-0039
Universal access to safe drinking water is essential to population health and wellbeing, as recognized in the Sustainable Development Goals (SDG). To develop targeted policies which improve urban access to improved water and ensure equity, there is the need to understand the spatial heterogeneity in drinking water sources and the factors underlying these patterns. Using the Shannon Entropy Index and the Index of Concentration at the Extremes at the enumeration area level, we analyzed census data to examine the spatial heterogeneity in drinking water sources and neighborhood income in the Greater Accra Metropolitan Area (GAMA), the largest urban agglomeration in Ghana. GAMA has been a laboratory for studying urban growth, economic security, and other concomitant socio-environmental and demographic issues in the recent past. The current study adds to this literature by telling a different story about the spatial heterogeneity of GAMA’s water landscape at the enumeration area level. The findings of the study reveal considerable geographical heterogeneity and inequality in drinking water sources not evidenced in previous studies. We conclude that heterogeneity is neither good nor bad in GAMA judging by the dominance of both piped water sources and sachet water (machine-sealed 500ml plastic bag of drinking water). The lessons from this study can be used to inform the planning of appropriate localized solutions targeted at providing piped water sources in neighborhoods lacking these services and to monitor progress in achieving universal access to improved drinking water as recognized in the SDG 6 and improving population health and wellbeing
Webb A, Allan F, Kelwick R, et al., 2022, Specific Nucleic AcId Ligation for the detection of Schistosomes: SNAILS, PLOS Neglected Tropical Diseases, Vol: 16, Pages: 1-19, ISSN: 1935-2727
Schistosomiasis, also known as bilharzia or snail fever, is a debilitating neglected tropical disease (NTD), caused by parasitic trematode flatworms of the genus Schistosoma, that has an annual mortality rate of 280,000 people in sub-Saharan Africa alone. Schistosomiasis is transmitted via contact with water bodies that are home to the intermediate host snail which shed the infective cercariae into the water. Schistosome lifecycles are complex, and while not all schistosome species cause human disease, endemic regions also typically feature animal infecting schistosomes that can have broader economic and/or food security implications. Therefore, the development of species-specific Schistosoma detection technologies may help to inform evidence-based local environmental, food security and health systems policy making. Crucially, schistosomiasis disproportionally affects low- and middle-income (LMIC) countries and for that reason, environmental screening of water bodies for schistosomes may aid with the targeting of water, sanitation, and hygiene (WASH) interventions and preventive chemotherapy to regions at highest risk of schistosomiasis transmission, and to monitor the effectiveness of such interventions at reducing the risk over time. To this end, we developed a DNA-based biosensor termed Specific Nucleic AcId Ligation for the detection of Schistosomes or ‘SNAILS’. Here we show that ‘SNAILS’ enables species-specific detection from genomic DNA (gDNA) samples that were collected from the field in endemic areas.
Moulds S, Chan ACH, Tetteh JD, et al., 2022, Sachet water in Ghana: a spatiotemporal analysis of the recent upward trend in consumption and its relationship with changing household characteristics, 2010-2017, PLoS One, Vol: 17, Pages: 1-22, ISSN: 1932-6203
The consumption of packaged water in Ghana has grown significantly in recent years. By 2017, “sachet water” – machine-sealed 500ml plastic bags of drinking water – was consumed by 33% of Ghanaian households. Reliance on sachet water has previously been associated with the urban poor, yet recent evidence suggests a customer base which crosses socioeconomic lines. Here, we conduct a repeated cross-sectional analysis of three nationally representative datasets to examine the changing demography of sachet water consumers between 2010 and 2017. Our results show that over the course of the study period sachet water has become a ubiquitous source of drinking water in Ghana, with relatively wealthy households notably increasing their consumption. In 2017, the majority of sachet water drinking households had access to another improved water source. The current rate and form of urbanisation, inadequate water governance, and an emphasis on cost recovery pose significant challenges for the expansion of the piped water supply network, leading us to conclude that sachet water will likely continue to be a prominent source of drinking water in Ghana for the foreseeable future. The main challenge for policymakers is to ensure that the growing sachet water market enhances rather than undermines Ghana’s efforts towards achieving universal and equitable access to clean drinking water and sanitation.
Hylton E, Noad L, Templeton MR, et al., 2022, The rate of vermi-compost accumulation within ‘Tiger Toilets’ in India, Environmental Technology, Vol: 43, Pages: 376-385, ISSN: 0959-3330
Tiger Toilets use a worm-based ecosystem to degrade human waste and have recently been demonstrated as a cost-effective innovation in on-site sanitation. The benefits over traditional pit latrines include slower fill rate, fewer odours, and safer emptying. However, a question remains around how to measure the rate of accumulation of vermi-compost and predict the fill rate into the future. In this study, fifteen Tiger Toilets of varying installation ages in the villages of Jejuri, Bhalgudi and Walhe/Adachiwadi, in Maharashtra province, India were investigated to determine the rate of filling. A laser measure was used to define cross-sections of the depth to vermi-compost layers within the Tiger Toilet digesters. Bench-scale column tests were used to estimate liquid infiltration rates from the digesters into the surrounding soils. Changes over time in the interior digester conditions were photographed and a video camera was installed in selected digesters to confirm and observe the worm activity in situ under red light. Calculated fill rates of the Tiger Toilets were significantly lower compared to estimated fill rates of traditional pit latrines of a similar size and usage rate. The infiltration of the liquid fraction of the waste into the surrounding soil was observed to be a key factor in filling.
Sfynia C, Bond T, Kanda R, et al., 2022, Simultaneous prediction of trihalomethanes, haloacetic acids, haloacetonitriles and haloacetamides using simulated distribution system tests, Environmental Science: Water Research and Technology, Vol: 8, Pages: 742-756, ISSN: 2053-1400
This study analysed the spatial and temporal occurrence of 29 disinfection by-products (DBPs) formed by chlorination and chloramination. Four full-scale treatment works, and distribution system locations were sampled, and the results were compared with laboratory-based simulated distribution system (SDS) tests. The DBPs monitored incorporated 4 trihalomethanes (THMs), 9 haloacetic acids (HAAs), 7 haloacetonitriles (HANs) and 9 haloacetamides (HAcAms). For the first time, SDS tests were shown to successfully simulate the levels and speciation of HANs and HAcAms in both chlorinated and chloraminated systems. While THM and HAA concentrations generally increased with water age, HAN and HAcAm concentrations fluctuated and resulted in less pronounced overall increases. To explore the impact of switching the disinfectant in distribution, free chlorine and chloramines were applied in the SDS tests, which showed that chloramination not only reduces the yields of THMs (by 34%) and HAAs (by 49%), but also HANs (by 61%) and HAcAms (by 51%), although it shifts speciation towards more brominated HAAs, HANs and HAcAms species when compared against chlorination. Overall, the aim of the study was to demonstrate that SDS tests can be recommended for the simultaneous estimation of THM, HAA, HAN and HAcAm concentrations in distribution systems and to assess the effect of potential DBP minimisation strategies, such as switching the disinfectant in distribution.
Krueger BC, Fowler GD, Templeton MR, et al., 2021, Faecal sludge pyrolysis: understanding the relationships between organic composition and thermal decomposition, Journal of Environmental Management, Vol: 298, Pages: 1-13, ISSN: 0301-4797
Sludge treatment is an integral part of faecal sludge management in non-sewered sanitation settings. Development of pyrolysis as a suitable sludge treatment method requires thorough knowledge about the properties and thermal decomposition mechanisms of the feedstock. This study aimed to improve the current lack of understanding concerning relevant sludge properties and their influence on the thermal decomposition characteristics. Major organic compounds (hemicellulose, cellulose, lignin, protein, oil and grease, other carbohydrates) were quantified in 30 faecal sludge samples taken from different sanitation technologies, providing the most comprehensive organic faecal sludge data set to date. This information was used to predict the sludge properties crucial to pyrolysis (calorific value, fixed carbon, volatile matter, carbon, hydrogen). Samples were then subjected to thermogravimetric analysis to delineate the influence of organic composition on thermal decomposition. Septic tanks showed lower median fractions of lignin (9.4%dwb) but higher oil and grease (10.7%dwb), compared with ventilated improved pit latrines (17.4%dwb and 4.6%dwb respectively) and urine diverting dry toilets (17.9%dwb and 4.7%dwb respectively). High fixed carbon fractions in lignin (45.1%dwb) and protein (18.8%dwb) suggested their importance for char formation, while oil and grease fully volatilised. For the first time, this study provided mechanistic insights into faecal sludge pyrolysis as a function of temperature and feedstock composition. Classification into the following three phases was proposed: decomposition of hemicellulose, cellulose, other carbohydrates, proteins and, partially, lignin (200–380 °C), continued decomposition of lignin and thermal cracking of oil and grease (380–500 °C) and continued carbonisation (>500 °C). The findings will facilitate the development and optimisation of faecal sludge pyrolysis, emphasising the importance of considering the
Braun L, Sylivester YD, Zerefa MD, et al., 2021, Parameters for effective sand filtration of Schistosoma mansoni cercariae from water, Water Supply
Blyth J, Hazell L, Templeton MR, 2021, Immunological detection of thymine dimers in indigenous genomic DNA from pre-disinfection drinking water as an ultraviolet disinfection dosimeter, Environmental Science: Water Research and Technology, Vol: 7, Pages: 2010-2020, ISSN: 2053-1400
Culture-based methods are the primary methods used for the routine detection and enumeration of bacteria and viruses in water samples. In the context of ultraviolet (UV) disinfection, they are also the basis for reactor validation in drinking water treatment systems. However, the majority of microorganisms in drinking water are not culturable. In UV disinfection, the DNA of both the culturable and non-culturable microbial populations will form pyrimidine dimers in response to UV photon absorbance. In this research an enzyme-linked immuno-sorbent assay (ELISA) was used to detect thymine dimers in the extractable genomic DNA (gDNA) from the total microbial population in pre-disinfection drinking water as a UV disinfection dosimeter. The method was first optimised using “naked” (extracted prior to UV exposure) and in vivo (extracted post UV exposure) Escherichia coli gDNA, and then tested using water samplesfrom UK drinking water treatment plants. Samples were exposed to up to 120 mJ/cm2 of monochromatic (254 nm) UV light using a collimated beam device and an ELISA was applied to the gDNA. This approach, once optimised, resulted in linear relationships between the assay response and UV dose. This shows that ELISA-based enumeration of thymine dimers in total extractable gDNA from a mixed species population has the potential to provide a direct, relatively quick, sampling-based means of monitoring the UV disinfection dose being delivered by operating UV disinfection systems in drinking water treatment plants, without the need to spike a biodosimeter into the water nor take reactors out of service. Molecular techniques 2 measuring dimer formation may also offer the UV disinfection industry a method of demonstrating dose delivery where the culturing of target organisms is problematic.
Kelwick RJR, Webb AJ, Wang Y, et al., 2021, AL-PHA beads: bioplastic-based protease biosensors for global health applications, Materials Today, Vol: 47, Pages: 25-37, ISSN: 1369-7021
Proteases are multi-functional proteolytic enzymes that have complex roles in human health and disease. Therefore, the development of protease biosensors can be beneficial to global health applications. To this end, we developed Advanced proteoLytic detector PolyHydroxyAlkanoates (AL-PHA) beads – a library of over 20 low-cost, biodegradable, bioplastic-based protease biosensors. Broadly, these biosensors utilise PhaC-reporter fusion proteins that are bound to microbially manufactured polyhydroxyalkanoate beads. In the presence of a specific protease, superfolder green fluorescent reporter proteins are cleaved from the AL-PHA beads – resulting in a loss of bead fluorescence. The Tobacco Etch Virus (TEV) AL-PHA biosensor detected the proteolytic activity of at least 1.85 pM of AcTEV. AL-PHA beads were also engineered to detect cercarial elastase from Schistosoma mansoni-derived cercarial transformation fluid (SmCTF) samples, as well as cancer-associated metalloproteinases in extracellular vesicle and cell-conditioned media samples. We envision that AL-PHA beads could be further developed for use in resource-limited settings.
Hazell L, Allan F, Emery AM, et al., 2021, Ultraviolet disinfection of Schistosoma mansoni cercariae in water, PLOS Neglected Tropical Diseases, Vol: 15:7:e0009572, ISSN: 1935-2727
Moulds S, Buytaert W, Templeton MR, et al., 2021, Modeling the impacts of urban flood risk management on social inequality, Water Resources Research, Vol: 57, ISSN: 0043-1397
The exposure of urban populations to flooding is highly heterogeneous, with the negative impacts of flooding experienced disproportionately by the poor. In developing countries experiencing rapid urbanization and population growth a key distinction in the urban landscape is between planned development and unplanned, informal development, which often occurs on marginal, flood-prone land. Flood risk management in the context of informality is challenging, and may exacerbate existing social inequalities and entrench poverty. Here, we adapt an existing socio-hydrological model of human-flood interactions to account for a stratified urban society consisting of planned and informal settlements. In the first instance, we use the model to construct four system archetypes based on idealized scenarios of risk reduction and disaster recovery. We then perform a sensitivity analysis to examine the relative importance of the differential values of vulnerability, risk-aversion, and flood awareness in determining the relationship between flood risk management and social inequality. The model results suggest that reducing the vulnerability of informal communities to flooding plays an important role in reducing social inequality and enabling sustainable economic growth, even when the exposure to the flood hazard remains high. Conversely, our model shows that increasing risk aversion may accelerate the decline of informal communities by suppressing economic growth. On this basis, we argue for urban flood risk management which is rooted in pro-poor urban governance and planning agendas which recognize the legitimacy and permanence of informal communities in cities.
Blyth J, Templeton MR, Court S-J, et al., 2021, Assessment of indigenous surrogate microorganisms for UV disinfection dose verification, Water and Environment Journal, ISSN: 1747-6585
Krueger BC, Fowler GD, Templeton MR, 2021, Critical analytical parameters for faecal sludge characterisation informing the application of thermal treatment processes, Journal of Environmental Management, Vol: 280, ISSN: 0301-4797
Thermal processes for the treatment of faecal sludge such as pyrolysis or combustion offer complete destruction of pathogens, whilst allowing for energy and nutrient recovery. The development of such processes is currently constrained by a lack of knowledge on thermally relevant faecal sludge characteristics. This study investigated thirty faecal sludge samples from three sanitation technologies (ventilated improved pit latrines (VIP), urine diverting dry toilets (UD), septic tanks (ST)) and compared these by non-parametric statistical analysis. A focus was placed on parameters necessary for thermal process development and recoverable nutrient concentrations. The relevant characteristics ranged widely within technology groups. Calorific values and ash concentrations of 2.1–25.7 MJ/kg and 9.5–88.4% were observed for STs, of 9.2–13.9 MJ/kg and 40.9–61.5% for VIPs and of 3.9–18.1 MJ/kg and 18.8–81.3% for UDs. These two parameters show a strong linear inverse correlation and determine the minimum dewatering requirements from which a net energy recovery may be possible. Results suggest that more than 90% of samples can meet these requirements following commonly used dewatering technologies. A comparison across technologies provided strong evidence that the faecal sludge source significantly influences sludge composition, emphasized by higher median ratios of fixed carbon to volatile matter in VIPs (0.23) and UDs (0.23) compared to STs (0.15). The sanitation technology also influenced recoverable nutrient concentrations, with phosphorus and potassium concentrations generally ranging between 5.8–49.2 g/kg and 1.4–26.1 g/kg respectively. Compared to STs, median concentrations of phosphorus and potassium in VIPs were 3.4 and 3.8 times higher respectively, and 3.0 and 8.8 times higher in UDs. The findings highlight the importance of considering the faecal sludge source in the development of thermal treatment processes. This stud
Mayor-Smith I, Templeton MR, 2021, Development of a mercury free ultraviolet high pressure plasma discharge for disinfection, Water and Environment Journal, Vol: 35, Pages: 41-54, ISSN: 1747-6585
Ultraviolet (UV) disinfection is a critical and growing application for the disinfection of water. Current UV systems for disinfection applications are designed around the use of Low Pressure (LP) and High Pressure (HP) mercury based lamps. Increasing demand to reduce and ideally remove the use of mercury requires innovative adaptations and novel approaches to current technology. A potential alternative technology could be Light Emitting Diodes (LEDs) however with current low efficiencies, high costs and low operating powers a development gap for a high power mercury source has been identified. A mercury free tellurium based high pressure plasma was developed and assessed. Although relatively low efficiencies were measured compared to current mercury based technology rapid improvements are likely obtainable. Such an approach enables a novel adaptation to current technology utilising established; manufacturing facilities, approaches of UV system design and validation protocols. As a consequence it offers the potential for a rapid low cost transition to mercury free UV disinfection where no alternative is currently available.
Background:Schistosomiasis is a water-based disease acquired through contact with cercaria-infested water. Communities living in endemic regions often rely on parasite-contaminated freshwater bodies for their daily water contact activities, resulting in recurring schistosomiasis infection. In such instances, water treatment can provide safe water on a household or community scale. However, to-date there are no water treatment guidelines that provide information on how to treat water containing schistosome cercariae. Here, we rigorously test the effectiveness of chlorine against Schistosoma mansoni cercariae.Method:S. mansoni cercariae were chlorinated using sodium hypochlorite under lab and field condition. The water pH was controlled at 6.5, 7.0 or 7.5, the water temperature at 20°C or 27°C, and the chlorine dose at 1, 2 or 3 mg/l. Experiments were conducted up to contact times of 45 minutes. 100 cercariae were used per experiment, thereby achieving up to 2-log10 inactivations of cercariae. Experiments were replicated under field conditions at Lake Victoria, Tanzania.Conclusion:A CT (residual chlorine concentration x chlorine contact time) value of 26±4 mg·min/l is required to achieve a 2-log10 inactivation of S. mansoni cercariae under the most conservative condition tested (pH 7.5, 20°C). Field and lab-cultivated cercariae show similar chlorine sensitivities. A CT value of 30 mg·min/l is therefore recommended to disinfect cercaria-infested water, though safety factors may be required, depending on water quality and operating conditions. This CT value can be achieved with a chlorine residual of 1 mg/l after a contact time of 30 minutes, for example. This recommendation can be used to provide safe water for household and recreational water activities in communities that lack safe alternative water sources.
Sfynia C, Bond T, Kanda R, et al., 2020, The formation of disinfection by-products from the chlorination and chloramination of amides, Chemosphere, Vol: 248:125940, ISSN: 0045-6535
This study examined the potential of six aliphatic and aromatic amides, commonly found in natural waters or used as chemical aids in water treatment, to act as organic precursors for nine haloacetamides (HAcAms), five haloacetonitriles (HANs), regulated trihalomethanes (THMs) and haloacetic acids (HAAs) upon chlorination and chloramination. The impact of key experimental conditions, representative of drinking water, including pH (7 & 8), retention time (4 & 24 h) and bromide levels (0 & 100 μg/L), on the generation of the target DBPs was investigated. The highest aggregate DBP yields upon chlor(am)ination were reported for the aromatic and hydrophobic hydroxybenzamide; 2.7% ± 0.1% M/M (chlorination) and 1.7% M/M (chloramination). Increased reactivity was observed in aliphatic and hydrophilic compounds, acrylamide (2.5 ± 0.2% M/M) and acetamide (1.3 ± 0.2% M/M), in chlorination and chloramination, respectively. The addition of bromide increased average DBP yields by 50–70%. Relative to chlorination, the application of chloramines reduced DBP formation by 66.5% (without Br−) and by 46.4% (with Br−). However, bromine incorporation in HAAs and HAcAms was enhanced following chloramination, of concern due to the higher toxicological potency of brominated compounds.
Braun L, Hazell L, Webb AJ, et al., 2020, Determining the viability of Schistosoma mansoni cercariae using fluorescence assays: an application for water treatment, PLOS Neglected Tropical Diseases, Vol: 14, ISSN: 1935-2727
Background:Schistosome cercariae are the human-infectious stage of the Schistosoma parasite. They are shed by snail intermediate hosts living in freshwater, and penetrate the skin of the human host to develop into schistosomes, resulting in schistosomiasis infection. Water treatment (e.g. filtration or chlorination) is one way of cutting disease transmission; it kills or removes cercariae to provide safe water for people to use for activities such as bathing or laundry as an alternative to infested lakes or rivers. At present, there is no standard method for assessing the effectiveness of water treatment processes on cercariae. Examining cercarial movement under a microscope is the most common method, yet it is subjective and time-consuming. Hence, there is a need to develop and verify accurate, high-throughput assays for quantifying cercarial viability.Method:We tested two fluorescence assays for their ability to accurately determine cercarial viability in water samples, using S. mansoni cercariae released from infected snails in the Schistosomiasis Collection at the Natural History Museum, London. These assays consist of dual stains, namely a vital and non-vital dye; fluorescein diacetate (FDA) and Hoechst, and FDA and Propidium Iodide. We also compared the results of the fluorescence assays to the viability determined by microscopy.Conclusion:Both fluorescence assays can detect the viability of cercariae to an accuracy of at least 92.2% ± 6.3%. Comparing the assays to microscopy, no statistically significant difference was found between the method’s viability results. However, the fluorescence assays are less subjective and less time-consuming than microscopy, and therefore present a promising method for quantifying the viability of schistosome cercariae in water samples.
Krueger BC, Fowler GD, Templeton MR, et al., 2020, Resource recovery and biochar characteristics from full-scale faecal sludge treatment and co-treatment with agricultural waste, Water Research, Vol: 169:115253, ISSN: 0043-1354
Unsafe disposal of faecal sludge from onsite sanitation in low-income countries has detrimental effects on public health and the environment. The production of biochar from faecal sludge offers complete destruction of pathogens and a value-added treatment product. To date, research has been limited to the laboratory. This study evaluates the biochars produced from the co-treatment of faecal sludge from septic tanks and agricultural waste at two full-scale treatment plants in India by determining their physical and chemical properties to establish their potential applications. The process yielded macroporous, powdery biochars that can be utilised for soil amendment or energy recovery. Average calorific values reaching 14.9 MJ/kg suggest use as solid fuel, but are limited by a high ash content. Phosphorus and potassium are enriched in the biochar but their concentrations are restricted by the nutrient-depleted nature of septic tank faecal sludge. High concentrations of calcium and magnesium led to a liming potential of up to 20.1% calcium carbonate equivalents, indicating suitability for use on acidic soils. Heavy metals present in faecal sludge were concentrated in the biochar and compliance for soil application will depend on local regulations. Nevertheless, heavy metal mobility was considerably reduced, especially for Cu and Zn, by 51.2–65.2% and 48.6–59.6% respectively. Co-treatment of faecal sludge with other carbon-rich waste streams can be used to influence desired biochar properties. In this case, the addition of agricultural waste increased nutrient and fixed carbon concentrations, as well as providing an additional source of energy. This study is a proof of concept for biochar production achieving full-scale faecal sludge treatment. The findings will help inform appropriate use of the treatment products as this technology becomes more commonly applied.
Templeton MR, 2019, Achieving real-world impact, Environmental Science: Water Research and Technology, Vol: 5, Pages: 2070-2071, ISSN: 2053-1400
Hazell L, Braun L, Templeton MR, 2019, Ultraviolet sensitivity of WASH (water, sanitation, and hygiene) related helminths: a systematic review, PLOS Neglected Tropical Diseases, Vol: 13:e0007777
Dewhurst RN, Furlong C, Tripathi S, et al., 2019, Evaluating the viability of establishing container-based sanitation in low-income settlements, Waterlines, Vol: 38, Pages: 154-169, ISSN: 1756-3488
Container-based sanitation (CBS) services operate in a number of low-income urban settlements across the globe, providing sanitation services where other on-site and off-site sanitation systems face logistical and environmental restrictions. The viability of each CBS service is influenced by a number of location-specific factors. Drawing on an initial review of existing CBS services, this paper identifies and evaluates these factors in relation to establishing CBS in a new service location. By applying a weighted scoring matrix to these factors, the potential viability of CBS services has been assessed for urban informal settlements in Kathmandu Valley, Nepal. The viability of CBS services in these settlements was found to be most influenced by the current availability of basic sanitation facilities, the unfamiliarity with paying for sanitation services, and the universally adopted practice of anal cleansing with water. The process and scoring matrix developed and subsequently applied in Nepal are recommended as part of the pre-feasibility stage assessment where a CBS service is being considered as a sanitation option in new locations.
Charani E, Cunnington AJ, Yousif AHA, et al., 2019, In transition: current health challenges and priorities in Sudan, BMJ Global Health, Vol: 4:e001723, ISSN: 2059-7908
A recent symposium and workshop in Khartoum, the capital of the Republic of Sudan, brought together broad expertise from three universities to address the current burden of communicable and non-communicable diseases facing the Sudanese healthcare system. These meetings identified common challenges that impact the burden of diseases in the country, most notably gaps in data and infrastructure which are essential to inform and deliver effective interventions. Non-communicable diseases, including obesity, type 2 diabetes, renal disease and cancer are increasing dramatically, contributing to multimorbidity. At the same time, progress against communicable diseases has been slow, and the burden of chronic and endemic infections remains considerable, with parasitic diseases (such as malaria, leishmaniasis and schistosomiasis) causing substantial morbidity and mortality. Antimicrobial resistance has become a major threat throughout the healthcare system, with an emerging impact on maternal, neonatal, and paediatric populations. Meanwhile, malnutrition, micronutrient deficiency, and poor perinatal outcomes remain common and contribute to a lifelong burden of disease. These challenges echo the UN sustainable development goals and concentrating on them in a unified strategy will be necessary to address the national burden of disease. At a time when the country is going through societal and political transition, we draw focus on the country and the need for resolution of its healthcare needs.
Destiani R, Templeton MR, 2019, Chlorination and ultraviolet disinfection of antibiotic-resistant bacteria and antibiotic resistance genes in drinking water, AIMS Environmental Science, Vol: 6, Pages: 222-241, ISSN: 2372-0352
Ritson JP, Croft JK, Clark JM, et al., 2019, Sources of dissolved organic carbon (DOC) in a mixed land use catchment (Exe, UK), Science of the Total Environment, Vol: 666, Pages: 165-175, ISSN: 0048-9697
Many catchment management schemes in the UK have focussed on peatland restoration to improve ecosystem services such as carbon sequestration, water quality and biodiversity. The effect of these schemes on dissolved organic carbon (DOC) flux is critical in understanding peatland carbon budgets as well as the implications for drinking water treatment. In many catchments, however, peatland areas are not the only source of DOC, meaning that their significance at the full catchment scale is unclear. In this paper we have evaluated the importance of different land uses as sources of DOC by combining three datasets obtained from the Exe catchment, UK. The first dataset comprises a weekly monitoring record at three sites for six years, the second, a monthly monitoring record of 25 sites in the same catchment for one year, and the third, an assessment of DOC export from litter and soil carbon stocks. Our results suggest that DOC concentration significantly increased from the peaty headwaters to the mixed land-use areas (ANOVA F = 12.52, p < 0.001, df = 2), leading to higher flux estimates at the downstream sites. We present evidence for three possible explanations: firstly, that poor sampling of high flows may lead to underestimation of DOC flux, second, that there are significant sources of DOC besides the peatland headwaters, and finally, that biological- and photo-degradation decreases the influence of upstream DOC sources. Our results provide evidence both for the targeting of catchment management in peatland areas as well as the need to consider DOC from agricultural and forested areas of the catchment.
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