The cost-effectiveness of using latrine dehydrated and pasteurization pellets and struvite: Experimental evidence from South Africa

The pit latrine paradox in low-income settings: A sanitation technology of choice or a pollution hotspot?

Pit latrines are widely promoted to improve sanitation in low-income settings, but their pollution and health risks receive cursory attention. The present narrative review presents the pit latrine paradox; (1) the pit latrine is considered a sanitation technology of choice to safeguard human health, and (2) conversely, pit latrines are pollution and health risk hotspots. Evidence shows that the pit latrine is a 'catch-all' receptacle for household disposal of hazardous waste, including; (1) medical wastes (COVID-19 PPE, pharmaceuticals, placenta, used condoms), (2) pesticides and pesticide containers, (3) menstrual hygiene wastes (e.g., sanitary pads), and (4) electronic wastes (batteries). Pit latrines serve as hotspot reservoirs that receive, harbour, and then transmit the following into the environment; (1) conventional contaminants (nitrates, phosphates, pesticides), (2) emerging contaminants (pharmaceuticals and personal care products, antibiotic resistance), and (3) indicator organisms, and human bacterial and viral pathogens, and disease vectors (rodents, houseflies, bats). As greenhouse gas emission hotspots, pit latrines contribute 3.3 to 9.4 Tg/year of methane, but this could be an under-estimation. Contaminants in pit latrines may migrate into surface water, and groundwater systems serving as drinking water sources and pose human health risks. In turn, this culminates into the pit latrine-groundwater-human continuum or connectivity, mediated via water and contaminant migration. Human health risks of pit latrines, a critique of current evidence, and current and emerging mitigation measures are presented, including isolation distance, hydraulic liners/ barriers, ecological sanitation, and the concept of a circular bioeconomy. Finally, future research directions on the epidemiology and fate of contaminants in pit latrines are presented. The pit latrine paradox is not meant to downplay pit latrines' role or promote open defaecation. Rather, it seeks to stimulate discussion and research to refine the technology to enhance its functionality while mitigating pollution and health risks.

Why do We Know So Much and Yet So Little? A Scoping Review of Willingness to Pay for Human Excreta Derived Material in Agriculture

Challenges associated with rapid population growth, urbanization, and nutrient mining have seen increased global research and development towards ‘waste to wealth’ initiatives, circular economy models, and cradle-to-cradle waste management principles. Closing the nutrient loop through safe recovery and valorization of human excreta for agricultural use may provide a sustainable method of waste management and sanitation. Understanding the market demand is essential for developing viable waste management and sanitation provision business models. The pathways and processes for the safe recovery of nutrients from human excreta are well-documented. However, only anecdotal evidence is available on the willingness to pay for human excreta-derived material in agriculture. This review closes this gap by identifying and synthesizing published evidence on farmers’ willingness to pay for human excreta-derived material for agricultural use. The Scopus and Web of Science search engines were used to search for the literature. The search results were screened, and the data were extracted, charted, and synthesized using the DistillerSR web-based application. The findings show that understanding willingness to pay for human excreta-derived material is still a nascent and emerging research area. Gender, education, and experience are common factors that influence the farmers’ willingness to pay. The findings show that pelletization, fortification, labeling, packaging, and certification are essential attributes in product development. The wide-scale commercialization can be achieved through incorporation of context-specific socioeconomic, religious and cultural influences on the estimation of willingness to pay. Promoting flexible legislation procedures, harmonization of regional legislations, and creating incentives for sustainable waste recovery and reuse may also promote the commercialization of circular nutrient economy initiatives. More empirical studies are required to validate willingness to pay estimates, especially using the best practice for conducting choice experiments.