Evaluation of Chitosans as Coagulants-Flocculants to Improve Sand Filtration for Drinking Water Treatment.

The World Health Organization (WHO) reports that two billion people worldwide lack access to safely managed water sources, including 1.2 billion who already have access to improved water sources. In many countries, household point-of-use (POU) water-treatment options are used to remove or deactivate microorganisms in water, but not all POU technologies meet WHO performance requirements to achieve safe drinking water. To improve the effectiveness of POU technologies, the use of multiple treatment barriers should be used as a way to increase overall treatment performance. The focus of this research is to evaluate multiple barrier treatment using chitosan, an organic coagulant−flocculant, to improve microbial and turbidity reductions in combination with sand filtration. Bench-scale intermittently operated sand filters with 16 cm layers of sands of two different grain sizes representing slow and rapid sand filters were dosed daily over 57 days with microbially spiked surface water volumes corresponding to household use. E. coli bacteria and MS2 coliphage virus reductions were quantified biweekly (N = 17) using culture methods. Bacteria and virus removals were significantly improved over sand filtration without chitosan pretreatment (Wilcoxon Rank-Sum, p < 0.05). When water was pretreated at an optimal chitosan dose of 10 mg/L followed by sand filtration, log10 reductions in bacteria and viruses met the two-star WHO performance level of effectiveness. Microbial and turbidity reductions generally improved over the filter operating period but showed no trends with filtration rates.

Microbial reductions and physical characterization of chitosan flocs when using chitosan acetate as a cloth filter aid in water treatment.

The World Health Organization (WHO) estimates 2.1 billion people lack access to safely managed water. Cloth filtration is often employed in rural and developing communities of South Asia for point-of-use water treatment, but bacteria and viruses are too small for efficient removal by this filtration method. Chitosan is a biodegradable, cationic, organic polymer derived from the chemical treatment of chitin that acts as a coagulant and flocculant of contaminant of microbes and other particles in water, thereby facilitating filtration of microbes. This research 1) evaluated the use of chitosan acetate as a pre-treatment coagulation-flocculation process followed by cloth filtration for microbial reductions and 2) assessed floc particle size under three stirring conditions. E. coli KO11 bacteria and MS2 coliphage virus removals were quantified using culture-based methods. Chitosan acetate coagulation-flocculation pre-treatment of water, followed by cloth filtration, met or exceeded the protective (2-star) WHO performance levels for bacteria (2 log10 reduction) and viruses (3 log10 reduction), and filtrate turbidity was consistently reduced to < 1 NTU, meeting United States Environmental Protection Agency (EPA) and WHO targets.

Occupational health outcomes among sanitation workers: A systematic review and meta-analysis.

BACKGROUND: Sanitation workers are essential to global public health and societal wellbeing. However, the health risks and outcomes associated with exposure to occupational risk factors among sanitation workers are neither well understood nor well quantified. We undertook a systematic review to (1) identify occupational risk factors among sanitation workers and (2) assess the effect of occupational exposure to human fecal sludge and wastewater on selected health outcomes among these workers. METHODS: We searched four databases (i.e., PubMED, MEDLINE, EMBASE, and LILACS) for eligible studies from inception through to January 01, 2020. The included population was workers ≥15 years engaged, formally or informally, in installing, operating, servicing, cleaning or emptying a sanitation technology at any step of the sanitation chain. The included comparator was workers in other occupations or the general population. Eligible outcomes were: mortality (any or all causes), gastroenteritis, occupational injuries, respiratory diseases, musculoskeletal disorders, and mental and social health conditions. Risk of bias was assessed separately on exposure assessment and health outcome using a modified Liverpool Quality Assessment Tool (LQAT). We pooled sufficiently homogenous studies using inverse variance meta-analysis with random effects. RESULTS: A total of 65 studies (9 cohort studies, 56 cross-sectional studies) met the inclusion criteria. One quarter of studies (n = 15) were from middle-income countries. Few studies assessed occupational risk factor exposures directly; most assigned exposure via proxy of occupation of sanitation worker. We judged nearly all studies to have "high risk of bias" in exposure and outcome assessment. Despite these limitations, the consistency of the overall evidence suggests that sanitation workers are at increased risk of gastroenteritis and respiratory conditions, and may be at increased risk of musculoskeletal disorders and mental/social health conditions. The pooled odds ratio for hepatitis A--the only outcome deemed suitable for meta-analysis--was 2.09 (95% Predicted Interval: 1.39-3.00, 12 studies). There was conflicting evidence from studies of increased risk of mortality; only one study reported on injuries. CONCLUSION: Despite a large number of studies, there is limited evidence to date of the health risks faced by sanitation workers, particularly among groups that may be at particular risk-- women, informal workers and those living in low-income countries. Nevertheless, the research to date provides suggestive evidence of elevated occupational risk among sanitation workers across a range of health condition. More research is needed to improve the current bodies of evidence for all included health outcomes to be able to quantify disease burden among this occupational group.

Chitosan Coagulation Pretreatment to Enhance Ceramic Water Filtration for Household Water Treatment.

Viruses are major contributors to the annual 1.3 million deaths associated with the global burden of diarrheal disease morbidity and mortality. While household-level water treatment technologies reduce diarrheal illness, the majority of filtration technologies are ineffective in removing viruses due to their small size relative to filter pore size. In order to meet the WHO health-based tolerable risk target of 10-6 Disability Adjusted Life Years per person per year, a drinking water filter must achieve a 5 Log10 virus reduction. Ceramic pot water filters manufactured in developing countries typically achieve less than 1 Log10 virus reductions. In order to overcome the shortfall in virus removal efficiency in household water treatment filtration, we (1) evaluated the capacity of chitosan acetate and chitosan lactate, as a cationic coagulant pretreatment combined with ceramic water filtration to remove lab cultured and sewage derived viruses and bacteria in drinking waters, (2) optimized treatment conditions in waters of varying quality and (3) evaluated long-term continuous treatment over a 10-week experiment in surface waters. For each test condition, bacteria and virus concentrations were enumerated by culture methods for influent, controls, and treated effluent after chitosan pretreatment and ceramic water filtration. A > 5 Log10 reduction was achieved in treated effluent for E.coli, C. perfringens, sewage derived E. coli and total coliforms, MS2 coliphage, Qß coliphage, ΦX174 coliphage, and sewage derived F+ and somatic coliphages.

Application of tools to monitor environmental conditions, identify exposures, and inform decision-making to improve infection prevention and control practices in Malawian maternity wards.

Healthcare-acquired infections (HAIs) contribute to maternal and neonatal morbidity and mortality, especially in low- and middle-income countries (LMICs). Deficient environmental health (EH) conditions and infection prevention and control (IPC) practices in healthcare facilities (HCFs) contribute to the spread of HAIs, but microbial sampling of sources of contamination is rarely conducted nor reported in low-resource settings. The purpose of this study was to assess EH conditions and IPC practices in Malawian HCFs and evaluate how EH deficiencies contribute to pathogen exposures and HAIs, and to provide recommendations to inform improvements in EH conditions using a mixed-methods approach. Thirty-one maternity wards in government-run HCFs were surveyed in the three regions of Malawi. Questionnaires were administered in parallel with structured observations of EH conditions and IPC practices and microbial testing of water sources and facility surfaces. Results indicated significant associations between IPC practices and microbial contamination. Facilities where separate wards were not available for mothers and newborns with infections and where linens were not used for patients during healthcare services were more likely to have delivery tables with surface contamination (relative risk = 2.23; 1.49, 3.34). E. coli was detected in water samples from seven (23%) HCFs. Our results suggest that Malawian maternity wards could reduce microbial contamination, and potentially reduce the occurrence of HAIs, by improving EH conditions and IPC practices. HCF staff can use the simple, low-cost EH monitoring methods used in this study to incorporate microbial monitoring of EH conditions and IPC practices in HCFs in low-resource settings.