Domestic access to water in a decentralized truck-to-cistern system: a case study in the Northern Village of Kangiqsualujjuaq, Nunavik (Canada).

Municipal water supply through truck-to-cistern systems is common in northern Canada. Household satisfaction and concerns about water services likely impact user preferences and practices. This case study explores household perspectives and challenges with regard to domestic access to water in a decentralized truck-to-cistern system. A case study was conducted in the Northern Village of Kangiqsualujjuaq, Nunavik (Quebec, Canada). A paper-based questionnaire was completed by 65 households (one quarter of the population). Many households (37%) reported not drinking tap water from the truck-to-cistern system. Chlorine taste was a frequently reported concern, with those households being significantly less likely to drink water directly from the tap (p = 0.002). Similarly, households that reported a water shortage in the previous week (i.e., no water from the tap at least once) (33%) were more likely to express dissatisfaction with delivered water quantity (rs = 0.395, p = 0.004). Interestingly, 77% of households preferred using alternative drinking water sources for drinking purposes, such as public tap at the water treatment plant, natural sources or bottled water. The study underscores the importance of considering household perspectives to mitigate the risks associated with service disruptions and the use of alternative sources for drinking purposes.

A bibliometric analysis of global research on drinking water and health in low- and lower-middle-income countries.

Heightened interest in drinking water research in recent decades has been aimed at narrowing the knowledge gaps surrounding water and health in a global pursuit to provide safely managed drinking water services to populations who continue to lack access. This study used bibliometrics and network analysis to produce a global overview of publications and groups that have contributed to research on drinking water and health in low- and lower-middle-income countries (LLMICs). The United States and the United Kingdom, which have historically dominated the field based on the production and impact of scientific literature, remain at the center of international collaborative research partnerships with emerging countries. However, in recent years, the volume of publications produced by India has surpassed that of the United States while Bangladesh is ranked third for the strongest international collaborations. Iran and Pakistan are also emerging as major producers of research, yet publications out of these countries and India remain disproportionately restricted behind paywalls. Contamination, diarrheal disease, and water resources are the themes that characterize the majority of research on water and health. These findings may be used to accelerate equitable, inclusive research in the realm of water and health, thereby enabling gaps in global drinking water inequalities to be filled.

Towards globally relevant, small-footprint dewatering solutions: Optimal conditioner dose for highly variable blackwater from non-sewered sanitation.

Globally, the sanitation needs of three billion people are met by non-sewered sanitation. Small-footprint treatment technologies are needed that are appropriate for dense urban areas. Blackwater (BW) (or fecal sludge), contains more than 95% liquid, and dewatering it without conditioning requires large footprints. Chemically-enhanced dewatering with conditioners is a promising option to increase dewatering performance and reduce required footprints. However, before implementation of this solution there is a need for increased knowledge on selection and dosing of conditioners. This study evaluated bio-based and synthetic conditioners (chitosan, tannin-, and starch-based, synthetic with and without poly-acrylamide) with 14 types of BW from five countries. The supernatant after settling with jar-tests was analyzed to quantify optimal dose and dewatering performance. The reduction of total chemical oxygen demand (COD) was >55%, achieved by removal of particulate constituents with mainly soluble COD remaining in the supernatant. A reduction in particulate COD could lead to increased efficiency of soluble COD in supernatant treatment. Bio-based conditioners are as effective as synthetic conditioners, and when performance was variable, it was due to differing properties of TSS, TS, EC and pH. Optimal conditioner dose for synthetic conditioners and chitosan could be predicted using concentrations of total solids (TS) (R2 > 0.7), whereas optimal dose for starch- and tannin-based conditioners could be predicted with electrical conductivity (EC) (R2 > 0.8), and colloid titration (R2 > 0.8). In addition, real-time optical TSS and EC sensors could accurately predict chitosan dose for fresh BW treated at source (R2 = 0.97, R2 = 0.95). This study validates that use of conditioners for dewatering with highly variable BW can be implemented with real-time measurements for optimal dose, in globally relevant implementations.

Trends in access to water and sanitation in Malawi: progress and inequalities (1992-2017).

Billions of people globally gained access to improved drinking water sources and sanitation in the last decades, following effort towards achieving the Millennium Development Goals. Global progress remains a general indicator as it is unclear if access is equitable across groups of the population. Agenda 2030 calling for `leaving no one behind', there is a need to focus on the variations of access in different groups of the population, especially in the context of low- and middle-income countries including Malawi. We analyzed data from Demographic Health Survey (DHS) and Multiple Indicator Cluster Survey (MICS) to describe emerging trends on progress and inequalities in water supply and sanitation services over a 25-year period (1992-2017), as well as to identify the most vulnerable populations in Malawi. Data were disaggregated with geographic and socio-economic characteristics including regions, urban and rural areas, wealth and education level. Analysis of available data revealed progress in access to water and sanitation among all groups of the population. The largest progress was generally observed in the groups that were further behind at the baseline year, which likely reflects good targeting in interventions/improvements to reduce the gap in the population. Overall, results demonstrated that some segments of the population - foremost poorest Southern rural populations - still have limited access to water and are forced to practise open defecation. Finally, we suggest including standardized indicators that address safely managed drinking water and sanitation services in future surveys and studies to increase the accuracy of national estimates.

Dominant decomposition pathways in pit latrines: a commentary.

In a recent article an assessment of decomposition within pit latrines measured with regard to chemical oxygen demand (COD) reductions was reported on. Some fundamental concerns were raised with regard to a key assumption of the study. The alternative perspective that is presented here does not support the study's conclusion that anaerobic processes are the dominant decomposition pathway in pit latrines. Furthermore, it is argued that their analysis and some implications of their data interpretation can be viewed in a different manner.

Evaluation of semidecentralized emergency drinking water treatment.

This study evaluates the potential for a novel semidecentralized approach that uses coagulant disinfectant products (CDPs) for humanitarian water treatment, by testing two commercially available products (CDP-W and CDP-T). Their performances were evaluated against the relevant water quality treatment objectives (The Sphere Project) under laboratory conditions, using a standardized testing protocol with both synthetic and natural surface test waters. Tests indicated a satisfactory performance by one of the products (CDP-W) with respect to humanitarian water quality objectives, (i.e., free chlorine residual, pH, and turbidity) that was dependent on initial water quality characteristics. Adequate bacterial inactivation (final thermotolerant coliform concentration of < 1 cfu/100 mL) was always attained and log reductions of up to 5 were achieved. The other product (CDP-T) did not exhibit any measurable coagulation and disinfection properties, indicating the variability of product quality and the need to conduct evaluations such as the ones presented in this study. Such results are of relevance to relief agencies delivering water supply interventions.

Effects of temperature and pH on reduction of bacteria in a point-of-use drinking water treatment product for emergency relief.

The effects of temperature and pH on the water treatment performance of a point-of-use (POU) coagulant/disinfectant product were evaluated. Cold temperatures (∼5°C) reduced the bactericidal efficiency of the product with regard to Escherichia coli and total coliform log(10) reductions.

pH-Dependent retention changes during membrane filtration of aluminum-coagulated solutions and the effect of precentrifugation.

During jar tests on alum-based drinking water treatment, dissolved Al determinations on solutions coagulated at pH ≥ 6.5 were not reproducible. These determinations were performed by inductively coupled plasma mass spectrometry after syringe filtration (0.45 µm polyethersulfone membrane). In order to better define these anomalies, the filtrates were collected in sequential fractions of 7.5 mL. At coagulation pHs of 6.5 and 7.0, retention changes were demonstrated by large filtrate concentration reductions at all temperatures tested (0.1, 5.0, and 17.0 °C). In all cases, the concentrations converged to levels <50 µg/L within the fourth sequential fraction. In comparison, no retention change was observed for jar tests conducted at the same temperatures but in the low range of the minimum solubility domain, at pHs 5.5 and 6.0. The retention changes were also eliminated by precentrifugation (7000 g for 45 min; pH 6.5-7.2). At weaker precentrifugation conditions, as well as by varying membrane surface area or membrane fouling, the filtrate concentrations behaved according to a barrier buildup at the membrane-solution interface by unsettled flocculation residuals. The influence of flocculation time and temperature emphasized the importance of reaction rates, which could be enhanced at the interface by concentration polarization effects. These phenomena have implications on analytical protocols and on filtration in full-scale treatment.

Assessment of rain event effects on source water quality degradation and subsequent water treatment operations.

Heavy rainfall events can lead to the runoff of large amounts of dissolved and particulate matter into surface water sources that may represents challenges for drinking water treatment, such as membrane fouling, increases in chemical demands, and formation of various disinfection by products (DBPs) after disinfection, such as trihalomethanes (THM) and haloacetic acids (HAA). In this study, a framework is defined for analyzing water quality data in relation to climatic variables (rainfalls). The effects of 22 different rain events were assessed on an organic matter proxy (UV absorbance), and on different key water quality parameters for the coagulation step in a drinking water treatment plant. Extended impacts of rewetting events after long term dry period on source water quality were identified, with significant increases in raw water UV 254 nm that last almost 3 weeks. A significant effect on filtered water quality was also noticed and the potential impacts on finished waters quality was confirmed by HAA modelling results. Future studies could focus on the monitoring and modelling of other regulated DBPs such as THM as well as simulations of different scenarios of climate change to estimate the variability of DBPs and its precursors such as organic matter.

Evaluation and application of chlorine decay models for humanitarian emergency water supply contexts.

Chlorine is a widely used water disinfectant in humanitarian emergency water supply. However, its effective application can be limited by the uncertainty in initial dose determination. The target free chlorine residual in water should achieve both health objectives and aesthetic considerations, but the varying field conditions and changing source water quality may affect the performance of chlorination strategies. A chlorine dose predictive tool could assist in initial dose determination. To this end, an accurate chlorine decay kinetic model can serve as a strong foundation for developing such a tool. In this study, a literature search identified 7 basic chlorine decay kinetic models that were subsequently tested with 610 different chlorine decay test data (from a semi-systematic literature search and laboratory-generated results). The models were then ranked based on their goodness of fit (R2) and root mean square error. An empirical model, power models and parallel models were found able to fit most decay data with more than half of the regressions resulting in R2 value over 0.97. First order models can achieve R2 value above 0.95 when the data points in the rapid phase are excluded from the model fitting. The power models and parallel models can form a strong basis for developing a chlorine dose predictive tool if the power term and the ratio term (model parameters) can be controlled. An essential next step is to evaluate the relationships between easily obtainable water parameters in the field and the decay term in the models to allow rapid model calibration.

Testing specificity and sensitivity of wastewater-based epidemiology for detecting SARS-CoV-2 in four communities on Vancouver Island, Canada.

We report wastewater surveillance of the spread of SARS-CoV-2 based upon 24-h composite influent samples taken weekly from four wastewater treatment plants (WWTP) on Vancouver Island, BC, Canada between January 3, 2021 and July 10, 2021. Samples were analyzed by reverse transcription quantitative polymerase chain reaction targeting the N1 and N2 gene fragments of SARS-CoV-2 and a region of the replication associate protein of the pepper mottle mosaic virus (PMMoV) serving as endemic control. Only a small proportion of samples had quantifiable levels of N1 or N2. Overall case rates are weakly correlated with the concentration (gene copies/L) and with the flux of viral material influent to the WWTP (gene copies/day); the latter accounts for influent flow variations. Poisson multimodal rank correlation accounts for differences between the four WWTP and shows a significant correlation with a significant positive intercept. Receiver operator characteristics (ROC) analysis confirms a cut-off of cases based on amplified/not-amplified experimental data. At the optimal cut point of 19 (N1) or 17 (N2) cases/week/100,000 the sensitivity and specificity is about 75% for N1 and 67% for N2.

Comment on Khairul Zaman et al. Eco-Friendly Coagulant versus Industrially Used Coagulants: Identification of Their Coagulation Performance, Mechanism and Optimization in Water Treatment Process. Int. J. Environ. Res. Public Health 2021, 18, 9164.

In a recent contribution by Zaman and colleagues, a few issues were noted on the justification of their study, which performed a comparative assessment of chitosan as a proposed alternative to aluminum-based coagulants for drinking water treatment applications. We have provided further clarity around such issues, which apply to other studies on the same theme.

Evaluating self-reported measures and alternatives to monitor access to drinking water: A case study in Malawi.

Monitoring access to drinking water is complex, especially in settings where on premises water supply is not available. Although self-reported data are generally used to estimate coverage of access to drinking water, the relationship between self-reported time travelled and true time travelled is not well known in the context of water fetching. Further, water fetching is likely to impact the quantity and quality of water a household uses, but data and measures supporting this relationship are not well documented. The objective of this study was to appraise the validity and reliability of self-reported measurements used to estimate access coverage. A case study was conducted in Malawi to enhance understanding of the self-reported measures and alternatives available to assess and monitor access to drinking water in view of generating global estimates. Self-reported data were compared with objective observations and direct measurements of water quantity, quality and accessibility. Findings from this study highlight the variations between different measures such as self-reported and recorded collection time and raise awareness with regard to the use of self-reported data in the context of fetching water. Alternatives to self-reported indicators such as GPS-based or direct observations could be considered in surveys in view of improving data accuracy and global estimates.

Household practices in accessing drinking water and post collection contamination: A seasonal cohort study in Malawi.

Lack of access to safe drinking water on premises remains widespread in low- and middle-income countries. Interventions to improve access to safe water at the point of collection are essential, but water safety at the point of consumption is also an important consideration. This research aimed to 1) improve understanding of household practices in collecting water with respect to seasonality, and 2) to further assess risk associated with post-collection contamination from the point of collection to the point of consumption. A seasonal cohort study, including 115 households, was conducted in Malawi. Along with household surveys and observations, samples of water were tested for microbial water quality at four different stages of water collection: water source, collection container, storage container, cup of drinking water. Using E. coli as an indicator of contamination (cfu/100 ml), the risk of post-collection contamination was assessed. The results indicate that most water sources were free from contamination; contamination was proportionally lower in the dry season when more sources were found to be classified as having a very low risk of contamination. However, the level of risk of contamination was more likely to increase following collection in water sources that were initially free from contamination. Results show that the degradation in water quality from the point of collection to the point of consumption was more important in the rainy season, which is likely to be driven by the effect of seasonality on the household environment. Filling the collection container at the point of collection and storage at the point of consumption were found to be critical stages for an increased risk of E. coli contamination. Understanding household practices in accessing and handling water during both rainy and dry season is necessary to target appropriate interventions to reduce post-collection contamination.

Assessment of Decontamination and Reuse of Disposable Filter Funnels Used in Microbiological Water Quality Tests.

To monitor safely managed drinking water services, an increasing number of countries have integrated water quality testing for Escherichia coli into nationally-representative household surveys such as the Multiple Indicator Cluster Surveys (MICS). However, plastic waste generated during such water quality testing programs, mostly through the use of pre-sterilized disposable materials, is non-negligible. The objective of this study was to evaluate several re-use protocols for disposable filter funnels used by the MICS water quality test kits. Decontamination and re-use protocols were assessed in centralized laboratory and decentralized field settings and neither yielded positive results. Re-use of 100 mL sterile funnels decontaminated with an alcohol wipe resulted in a higher incidence of false positive results (i.e., positive contamination when processing sterile water), both in the laboratory and field; therefore, a higher proportion of positives tests can be expected if these components are re-used. Further improvements to the decontamination technique and training are needed before material re-use can be reliably adopted. Autoclaving the funnels for re-use is feasible, provided that there is capacity to re-package and distribute funnels in a sterile manner.

Reply to Comment on "Enumeration of Escherichia coli in Probiotic Products. Microorganisms 2019, 7. 437".

We thank Wassenaar and colleagues for their Comment on our recent paper [1] and appreciate the opportunity to address it [...].

Ultraviolet absorbance monitoring for removal of DBP-precursor in waters with variable quality: Enhanced coagulation revisited.

Enhanced coagulation can be an effective way to reduce disinfection by-product (DBP) precursor concentrations. Where turbidity is not extremely high, the natural organic matter concentration evaluated by total or dissolved organic carbon concentration or UV absorbance is known to be the most important factor for determining the adequate coagulant dose. Yet, treatment plant operators are often faced with difficult decisions when it comes to coagulant dosages: Should coagulation efforts and coagulant doses be consistent year-round when water quality changes seasonally? Should the coagulant dose be increased when DBP standards are not met, or has the maximum removal of DBP precursors been reached? The objective and novelty of this study is to revisit the concept of enhanced coagulation and to determine optimal coagulation guidelines based not just on the removal of common indicators such as DOC but on the removal of actual DBP precursors. Jar-tests (for DBP precursor removal evaluation) using alum were conducted under a range of conditions on 8 different natural/synthetic waters with varying physicochemical characteristics for subsequent chlorination over 48 h (for DBP formation potential). A coagulant-dose adjustment strategy based on UV254 monitoring was also implemented at a full-scale facility. Results show that, for the wide range of waters tested, an alum/UV254 stoichiometric dose of 180 ± 25 mg alum cm/L represents a point of diminishing return (i.e. it maximises DBP precursor removal). Another original result of this work is that this dose is applicable and equally efficient in all seasons, despite changes in water quality. For utilities with similar raw waters, this means that coagulation efforts should be proportional to the UV254 of the raw water, regardless of the season.

Occurrence and fate of ozonation disinfection by-products in two Canadian drinking water systems.

The occurrence and the fate of 18 ozonation by-products (OBPs) (17 different aldehydes and bromate) were studied over one year in two Canadian drinking water systems. This is the first and only study reporting the occurrence of all these non-halogenated aldehydes (NON-HALs) and haloacetaldehydes (HALs) simultaneously, based on the multi-point monitoring of water in full-scale conditions from source to distribution network. In general, the application of both post-ozonation and liquid chlorine contributed to the formation of OBPs (aldehydes and bromate). NON-HALs were present in higher concentrations than HALs. Formaldehyde, acetaldehyde, glyoxal and methylglyoxal were the most common forms of NON-HALs in the two water systems that were studied. Chloral hydrate (CH), the hydrated form of trichloroacetaldehyde, was the most dominant HAL observed. The nature of the organic matter and the water temperature proved to be important parameters for explaining the variability of aldehydes. Summer and autumn (warm seasons) were more favorable for the formation of chloral hydrate and bromate. The highest concentrations of NON-HALs were observed in spring.

Rapid Changes in Microbial Community Structures along a Meandering River.

Streams and rivers convey freshwater from lands to the oceans, transporting various organic particles, minerals, and living organisms. Microbial communities are key components of freshwater food webs and take up, utilize, and transform this material. However, there are still important gaps in our understanding of the dynamic of these organisms along the river channels. Using high-throughput 16S and 18S rRNA gene sequencing and quantitative PCR on a 11-km long transect of the Saint-Charles River (Quebec, CA), starting from its main source, the Saint-Charles Lake, we show that bacterial and protist community structures in the river drifted quickly but progressively downstream of its source. The dominant Operational Taxonomic Units (OTUs) of the lake, notably related to Cyanobacteria, decreased in proportions, whereas relative proportions of other OTUs, such as a Pseudarcicella OTU, increased along the river course, becoming quickly predominant in the river system. Both prokaryotic and protist communities changed along the river transect, suggesting a strong impact of the shift from a stratified lake ecosystem to a continuously mixed river environment. This might reflect the cumulative effects of the increasing water turbulence, fluctuations of physicochemical conditions, differential predation pressure in the river, especially in the lake outlet by benthic filter feeders, or the relocation of microorganisms, through flocculation, sedimentation, resuspension, or inoculation from the watershed. Our study reveals that the transit of water in a river system can greatly impact both bacterial and micro-eukaryotic community composition, even over a short distance, and, potentially, the transformation of materials in the water column.

Intestinal Parasites, Anemia and Nutritional Status in Young Children from Transitioning Western Amazon.

Young children are particularly vulnerable to the chronic sequelae of anemia, including poor nutritional status. The aim of this study was to assess intestinal parasitic-infections and nutritional status (anemia and linear growth) in preschool children living in contemporary Amazonian communities. A cross-sectional study measured children's intestinal parasites and hair-Hg (HHg)-biomarkers of fish consumption, hemoglobin levels, and growth (anthropometric Z-scores). Children came from traditional-living families (Itapuã), and tin-mining settlements (Bom Futuro) representing current transitioning populations. It covered 937 pre-school children (from 1 to 59 months of age) from traditional (247) and immigrant tin-mining families (688). There was a high prevalence of intestinal polyparasitic-infection in children from both communities, but mild anemia (hemoglobin concentrations) and moderate (chronic) malnutrition were more frequent in children from traditional families than in children from tin-mining settlers. Children from traditional families ate significantly more fish (HHg mean of 4.3 µg/g) than children from tin-mining families (HHg mean of 2.3 µg/g). Among traditional villagers, children showed a significant correlation (r = 0.2318; p = 0.0005) between hemoglobin concentrations and HHg concentrations. High rates of parasitic infection underlie the poverty and attendant health issues of young children in the Brazilian Amazon. The intestinal parasite burden affecting poor Amazonian children resulting from unsafe water, lack of sanitation and poor hygiene is the most urgent environmental health issue.