Chlorine Water Taste Threshold and Acceptability among Indigenous and Non-Indigenous Populations in Rural Panama.

Although gains in access to water services over the past two decades have been large, more than two billion people still lack access to safely managed drinking water. This study examines and compares free chlorine taste and acceptability thresholds of rural Indigenous Ngäbe and rural Latino Panamanians to study if taste aversion may be a limiting factor in chlorination of community systems in Panama using the three-alternative forced choice test methodology. This study is the first to establish a best-estimate taste threshold for a rural Indigenous group and the only study in Latin America to report best-estimate taste thresholds using those methods. Median taste thresholds were 0.87 mg/L Cl2 for Indigenous Ngäbe participants (n = 82) and 1.64 mg/L Cl2 for Latino participants (n = 64), higher than both the minimum concentration for biologically safe water (0.2 mg/L) and the recommended concentration range in Panama (0.3-0.8 mg/L). Median acceptability thresholds were established much higher than taste thresholds at 3.45 mg/L Cl2. The results show that the ability to accurately taste chlorine may not be the limiting factor for adoption of safe water initiatives in remote and Indigenous communities.

Rural Sanitation Sustainability Dynamics: Gaining Insight through Participatory and Simulation Modeling.

Improved sanitation provides many benefits to human health and well-being and is integral to achieving Sustainable Development Goal Six. However, many nations, including most of sub-Saharan Africa, are not on track to meeting sanitation targets. Recognizing the inherent complexity of environmental health, we used systems thinking to study sanitation sustainability in Uganda. Our study participants, 37 sanitation actors in three rural districts, were engaged in interviews, group model building workshops, and a survey. The resulting model was parametrized and calibrated using publicly available data and data collected through the Uganda Sanitation for Health Activity. Our simulations revealed slippage from improved sanitation in all study districts, a behavior reflected in real interventions. This implies that systemic changes-changes to the rules and relationships in the system-may be required to improve sanitation outcomes in this context. Adding reinforcing feedback targeting households' perceived value of sanitation yielded promising simulation results. We conclude with the following general recommendations for those designing sanitation policies or interventions: (1) conceptualize sanitation systems in terms of reinforcing and balancing feedback, (2) consider using participatory and simulation modeling to build confidence in these conceptual models, and (3) design many experiments (e.g., simulation scenarios) to test and improve understanding.

Do Sanitation Marketing Activities Increase Households' Likelihoods of Reaching Improved Sanitation or Involving Women in Decision Making?

Poor sanitation causes 30% of diarrheal deaths globally, and much of the world has struggled to finance top-down interventions. Sanitation marketing is a demand-led approach that uses a mixture of social and commercial marketing methods and direct sales to households. However, little is known about its impacts on household decision making. This mixed-methods study uses data from eight focus groups and 86,666 household surveys from participants in a five-year sanitation marketing program in Uganda. Logistic regression models identified 10 variables predicting attainment of improved (limited or basic) sanitation and four variables predicting female involvement in decision making. Triggering session attendance increased chances of reaching improved sanitation by 15-28%, depending on who attended, and by 19% if the household found the session motivational. Although women were engaged in decision-making conversations, they were not viewed as primary decision makers, even in female-headed households. Women were more likely to become involved in decision making if they had attended triggering sessions with men (+70%) or engaged with sales promoters alone (+74%) or with men (+78%). For both outcomes, joint activity engagement was more effective than male or female engagement alone. This work highlights two sanitation marketing activities as pathways to improving latrine coverage and women's decision-making agency.

Reductions in Children's Blood Lead Levels from a Drinking-Water Intervention in Madagascar, Sub-Saharan Africa.

One in three children globally is estimated to have blood lead levels (BLL) at or above the BLL reference value of 5 µg/dL with increased burden falling on low- and middle-income countries (LMIC). Within developed countries, aqueous lead is the predominant exposure route. However, aqueous lead exposure is rarely examined in the LMIC, leaving a gap in the literature that ignores a potentially significant route of exposure. Furthermore, limited lead-based remediation efforts around consumer products have been examined. This study investigates the importance of lead exposure from the water supply through a case study in Toamasina, Madagascar. The project measured aqueous lead and BLL of children pre- and postremediation efforts (i.e., removal of leaded pump components in hand pumps) to verify the impact of aqueous lead exposure within this community. Removal of the leaded pump components (i.e., piston and foot valves) and replacement with nonleaded components decreased aqueous lead levels below the World Health Organization provisional guideline of 10 µg/L in all but 4% of pumps tested. Measured BLL concentrations indicated a statistically significant decrease in BLL from pre- to postremediation. Furthermore, the remediation resulted in a decrease in BLL for 87% of children with the greatest changes in BLL observed for children with the highest preremediation concentrations. These findings point to a need for greater consideration of lead in drinking and cooking waters as an important exposure route in LMIC.

Systems Thinking for Effective Interventions in Global Environmental Health.

Environmental health risks such as household air pollution due to burning solid fuels, inadequate water, sanitation, and hygiene, and chemical pollution disproportionately affect the poorest and most marginalized populations. While billions of dollars and countless hours of research have been applied toward addressing these issues in both development and humanitarian contexts, many interventions fail to achieve or sustain desired outcomes over time. This pattern points to the perpetuation of linear thinking, despite the complex nature of environmental health within these contexts. There is a need and an opportunity to engage in critical reflection of the dominant paradigms in the global environmental health community, including how they affect decision-making and collective learning. These paradigms should be adapted as needed toward the integration of diverse perspectives and the uptake of systems thinking. Participatory modeling, complexity-aware monitoring, and virtual simulation modeling can help achieve this. Additionally, virtual simulation modeling is relatively inexpensive and can provide a low-stakes environment for testing interventions before implementation.

Passive In-Line Chlorination for Drinking Water Disinfection: A Critical Review.

The world is not on track to meet Sustainable Development Goal 6.1 to provide universal access to safely managed drinking water by 2030. Removal of priority microbial contaminants by disinfection is one aspect of ensuring water is safely managed. Passive chlorination (also called in-line chlorination) represents one approach to disinfecting drinking water before or at the point of collection (POC), without requiring daily user input or electricity. In contrast to manual household chlorination methods typically implemented at the point of use (POU), passive chlorinators can reduce the user burden for chlorine dosing and enable treatment at scales ranging from communities to small municipalities. In this review, we synthesized evidence from 27 evaluations of passive chlorinators (in 19 articles, 3 NGO reports, and 5 theses) conducted across 16 countries in communities, schools, health care facilities, and refugee camps. Of the 27 passive chlorinators we identified, the majority (22/27) were solid tablet or granular chlorine dosers, and the remaining devices were liquid chlorine dosers. We identified the following research priorities to address existing barriers to scaled deployment of passive chlorinators: (i) strengthening local chlorine supply chains through decentralized liquid chlorine production, (ii) validating context-specific business models and financial sustainability, (iii) leveraging remote monitoring and sensing tools to monitor real-time chlorine levels and potential system failures, and (iv) designing handpump-compatible passive chlorinators to serve the many communities reliant on handpumps as a primary drinking water source. We also propose a set of reporting indicators for future studies to facilitate standardized evaluations of the technical performance and financial sustainability of passive chlorinators. In addition, we discuss the limitations of chlorine-based disinfection and recognize the importance of addressing chemical contamination in drinking water supplies. Passive chlorinators deployed and managed at-scale have the potential to elevate the quality of existing accessible and available water services to meet "safely managed" requirements.

Meeting the Water and Sanitation Challenges of Underbounded Communities in the U.S.

Water and sanitation (wastewater) infrastructure in the United States is aging and deteriorating, with massive underinvestment over the past several decades. For many years, lack of attention to water and sanitation infrastructure has combined with racial segregation and discrimination to produce uneven access to water and wastewater services resulting in growing threats to human and environmental health. In many metropolitan areas in the U.S., those that often suffer disproportionately are residents of low-income, minority communities located in urban disadvantaged unincorporated areas on the margins of major cities. Through the process of underbounding (the selective expansion of city boundaries to exclude certain neighborhoods often based on racial demographics or economics), residents of these communities are disallowed municipal citizenship and live without piped water, sewage lines, and adequate drainage or flood control. This Perspective identifies the range of water and sanitation challenges faced by residents in these communities. We argue that future investment in water and sanitation should prioritize these communities and that interventions need to be culturally context sensitive. As such, approaches to address these problems must not only be technical but also social and give attention to the unique geographic and political setting of local infrastructures.

Health and Economic Consequences of Lead Exposure Associated with Products and Services Provided by the Informal Economy.

In low- and middle-income countries (LMICs), the presence of an informal economy can lead to human exposure to toxic metals such as lead (Pb). This paper demonstrates the local health and economic benefits of modifying practices within the informal economic sector in Madagascar. Specifically, leaded components in 504 locally manufactured household water pumps were replaced with unleaded components. Prior to the intervention, 32% of the household systems exhibited lead concentrations above the World Health Organization (WHO) provisional drinking water guideline of 10 µg/L, but after the intervention, fewer than 3% of the systems were in exceedance. The reduction of lead concentration is modeled to reduce the fraction of children with elevated BLLs (>5 µg/dL) from 34 to 13%. The reduction in BLLs is estimated to provide an average economic benefit of US$11 800 per child based on predicted increases in lifetime productivity. This corresponds to a total benefit of US$8.7 million for the 730 children aged 1-5 associated with the pumps, representing a return on investment of greater than 1000-to-1. Results demonstrate how the formation of partnerships between public, private, and civil society entities, as suggested by UN Sustainable Development Goal 17, can realize important local economic and health benefits in LMICs.

Moving up the Sanitation Ladder while Considering Function: An Assessment of Indigenous Communities, Pit Latrine Users, and Their Perceptions of Resource Recovery Sanitation Technology in Panama.

As households move up the sanitation ladder, health risks presumably decline but the corresponding technologies may require increasing operation and maintenance costs. One critique of the ladder is that it prioritizes technology and could be improved if it included a functional approach to monitoring, such as including aspects of environmental sustainability that consider resource recovery. Using analyses of data obtained from semi-structured interviews, surveys, and field observations, this study examines the functional transition toward improved sanitation technology as a household moves up the sanitation ladder with the added function of resource recovery (from pit latrines to composting latrines). The study took place in six indigenous Ngäbe communities in Panama. The results reveal that of 103 pit latrines studied, 88% were completed and in use, but only 35% were operated appropriately. Approximately 60% of pit latrine owners reported that they would use composting latrines, with compost as the primary perceived benefit. Barriers to adoption include lack of prior experience, user disgust of working with excrement, and the perceived amount of work required for operation. Overall, these findings indicate the importance of establishing demonstration projects and culturally aligned training for more complex sanitation technologies that enable resource recovery. The results have broad implications for understanding sanitation technology transitions in rural and indigenous settlements in other world regions.

Assessment of nutrient fluxes and recovery for a small-scale agricultural waste management system.

The efficiencies of removing or recovering nitrogen and phosphorus in widely implemented small-scale tubular anaerobic digesters are not well understood, as the technology is primarily promoted for its recovery of energy, not nutrients. The purpose of this study was to use nutrient mass balances to assess the fate of nitrogen and phosphorus in two tubular anaerobic digesters, specifically designed to digest animal manure, that were integrated with a conical batch reactor to precipitate struvite (MgNH4PO4) from the digester effluent. The field study showed that locally available products, bittern and soda ash, can be used as a magnesium source and for pH adjustment (respectively) in the struvite precipitation reactor. Results from the mass balances showed that PO43- and NH4+ were released from the manure during anaerobic digestion, increasing the concentrations of PO43- and NH4+ in the liquid phase (by 130% and 120%, respectively). Despite this increase in liquid-phase concentrations, average removals were 25% for total phosphorus and 4% for total nitrogen via sedimentation in the digesters. The digesters also removed an average of 87% of total suspended solids and 84% of chemical oxygen demand from the influent waste stream. During struvite precipitation, an average of 79% of PO43--P and 14% of NH4+-N was removed from the digester effluent. Harvested precipitate comprised (by mass) 9.9% Mg, 2.4% N, and 12.8% P, consistent with struvite formation. The treatment system offers dual benefits: improved sanitation and recovery of nutrients as a fertilizer that may also indirectly reduce surface water and groundwater degradation. Quantifying nutrient recovery from small-farm-generated agricultural waste and understanding recovery mechanisms can improve environmental management and facilitate progress toward the achievement of multiple Sustainable Development Goals by improving sanitation, promoting sustainable management of wastes and natural resources, improving food security, and supporting the ecological restoration of local agroecosystems.

Seven Approaches to Manage Complex Coupled Human and Natural Systems: A Sustainability Toolbox.

Since the publication of the Report of the World Commission on Environment and Development in 1987, there have been numerous studies on sustainability. These studies created new knowledge and tools for understanding and managing complex coupled human and natural systems. In this Critical Review, we used a topic modeling technique to analyze 12 526 peer-reviewed research articles and identify the research questions and the approaches that were used or developed in each of the studies. These approaches were then classified by function. The analysis revealed twenty-three categories of research questions and seven functional approach classes-design for sustainability, modeling of complexity, sustainability indicators, life cycle sustainability assessment, decision making support, sustainability governance, and engagement-each of which is described here as an individual approach or tool within a larger sustainability toolbox. The article concludes with a discussion about using the sustainability toolbox as an integrated knowledge system to support transdisciplinary study and decision-making.

Can Sanitation Technology Play a Role in User Perceptions of Resource Recovery? An Evaluation of Composting Latrine Use in Developing World Communities in Panama.

There remains a large unmet need for sanitation access throughout the world that compromises both human and environmental health. Opportunities exist to employ sanitation systems that better utilize and recover scarce resources from excreta such as water, energy, and nutrients. However, technologies such as a composting latrine may require more maintenance and close handling of feces compared to other sanitation technologies. This study aims to evaluate how use of on-site composting latrine technology and other demographic characteristics are associated with users' perceptions of excreta for resource recovery. Field observations and interviews of composting latrine users ( N = 201) and 200 perceptions surveys were administered to composting and non-composting latrine users in Indigenous and Latino communities in Panama. Of the completed composting latrines, 78% were in use and 65% of these were used properly. Compost latrine design and operational factors identified to improve were: anal wash capability, desiccant supply, children usage, and clogging urine tubes. Demographic categories associated with positive perceptions toward resource recovery ( p < 0.05) were ethnicity (14 out of 16 total statements) and sanitation type (11) then community origin (7), occupation (5), education (4), age (3), and gender (1).

Accelerating Innovation that Enhances Resource Recovery in the Wastewater Sector: Advancing a National Testbed Network.

This Feature examines significant challenges and opportunities to spur innovation and accelerate adoption of reliable technologies that enhance integrated resource recovery in the wastewater sector through the creation of a national testbed network. The network is a virtual entity that connects appropriate physical testing facilities, and other components needed for a testbed network, with researchers, investors, technology providers, utilities, regulators, and other stakeholders to accelerate the adoption of innovative technologies and processes that are needed for the water resource recovery facility of the future. Here we summarize and extract key issues and developments, to provide a strategy for the wastewater sector to accelerate a path forward that leads to new sustainable water infrastructures.

How Does Scale of Implementation Impact the Environmental Sustainability of Wastewater Treatment Integrated with Resource Recovery?

Energy and resource consumptions required to treat and transport wastewater have led to efforts to improve the environmental sustainability of wastewater treatment plants (WWTPs). Resource recovery can reduce the environmental impact of these systems; however, limited research has considered how the scale of implementation impacts the sustainability of WWTPs integrated with resource recovery. Accordingly, this research uses life cycle assessment (LCA) to evaluate how the scale of implementation impacts the environmental sustainability of wastewater treatment integrated with water reuse, energy recovery, and nutrient recycling. Three systems were selected: a septic tank with aerobic treatment at the household scale, an advanced water reclamation facility at the community scale, and an advanced water reclamation facility at the city scale. Three sustainability indicators were considered: embodied energy, carbon footprint, and eutrophication potential. This study determined that as with economies of scale, there are benefits to centralization of WWTPs with resource recovery in terms of embodied energy and carbon footprint; however, the community scale was shown to have the lowest eutrophication potential. Additionally, technology selection, nutrient control practices, system layout, and topographical conditions may have a larger impact on environmental sustainability than the implementation scale in some cases.

Managing Microbial Risks from Indirect Wastewater Reuse for Irrigation in Urbanizing Watersheds.

Limited supply of clean water in urbanizing watersheds creates challenges for safely sustaining irrigated agriculture and global food security. On-farm interventions, such as riverbank filtration (RBF), are used in developing countries to treat irrigation water from rivers with extensive fecal contamination. Using a Bayesian approach incorporating ethnographic data and pathogen measurements, quantitative microbial risk assessment (QMRA) methods were employed to assess the impact of RBF on consumer health burdens for Giardia, Cryptosporidium, rotavirus, norovirus, and adenovirus infections resulting from indirect wastewater reuse, with lettuce irrigation in Bolivia as a model system. Concentrations of the microbial source tracking markers pepper mild mottle virus and HF183 Bacteroides were respectively 2.9 and 5.5 log10 units lower in RBF-treated water than in the river water. Consumption of lettuce irrigated with river water caused an estimated median health burden that represents 37% of Bolivia's overall diarrheal disease burden, but RBF resulted in an estimated health burden that is only 1.1% of this overall diarrheal disease burden. Variability and uncertainty associated with environmental and cultural factors affecting exposure correlated more with QMRA-predicted health outcomes than factors related to disease vulnerability. Policies governing simple on-farm interventions like RBF can be intermediary solutions for communities in urbanizing watersheds that currently lack wastewater treatment.

Assessing the fate of Ascaris suum ova during mesophilic anaerobic digestion.

There is limited knowledge about the survival of geohelminths, which are soil-transmitted human pathogens, in mesophilic anaerobic digestion processes. This study examined the fate of embryonated and unembryonated Ascaris suum ova in six laboratory-scale mesophilic (35 °C) anaerobic digesters processing swine manure to identify their survival strategies and investigate potential mechanisms to enhance their destruction. There was no significant difference in inactivation of Ascaris suum ova in digesters operated at different solids residence times (SRT) or feeding frequencies. Ova exposed to an anaerobic environment became dormant, or remained unembryonated throughout their residence in the reactors. Approximately 65% of ova were able to retain their viability for up to 16 days, after which the rate of inactivation increased until nearly all ova were nonviable by day 24. In contrast, ova exposed to aerobic conditions did not become dormant and progressed through several developmental stages until day 16, after which nearly all ova were observed to be nonviable. In addition, only 35% of fully developed ova exposed to the anaerobic environment retained their viability by day 16 compared to 65% for dormant ova. Results suggest that some ova are physically destroyed during digestion and ova can be inactivated faster if their development cycle is aerobically triggered before entering the anaerobic digestion process. Results also suggest that transfer of resource recovery technologies such as mesophilic anaerobic digestion to developing world settings must account for local climatic and health conditions so mutually beneficial outcomes can be attained.