Quantities and qualities of fecal sludge: Experiences from field implementation with a Volaser in 7 countries during a pandemic

Abstract

Reasonable estimates for quantities and qualities (Q&Q) of fecal sludge that accumulate in onsite sanitation containments are fundamental for the design of appropriate management and treatment solutions, from community to city-scale. There are increasing attempts to improve Q&Q estimates, but current approaches are still at a conceptual level, and are not yet standardized with confirmed statistical relationships. To reach this level, we will need consistent approaches for planning, measuring, and global collaborations. Hence, the objectives of this study were: (1) to assess and compare Q&Q of fecal sludge from seven cities and communities, and explore statistical relationships that could be used to increase accuracy of Q&Q estimations; (2) to test and launch the Volaser device for measuring in situ volumes of fecal sludge; and (3) to capture lessons learned from field implementation with collaborators in seven countries during a global pandemic when no international travel was possible. The study took place in Ghana, India, Lebanon, Kenya, Sierra Leone, Uganda, and Zambia during the COVID-19 pandemic. Q&Qs were measured in 204 containments with a Volaser, laboratory analysis, and questionnaire. Results indicate that there are differences in Total Solids (TS) and Chemical Oxygen Demand (COD) in fecal sludge based on containment type, toilet type, source, and whether there is a water connection on the premises. Based on the results of this study, together with previously published open-source data, an empirical relationship for Volatile Solids (VS) and TS of 0.49 (R2 = 0.88) was established using 1,206 data points. For COD/TS, no significant relationship was observed. Developing such empirical relationships will be useful for planning and modeling approaches. An external evaluation was conducted to evaluate overall project management, Volaser technology transfer, and effects of collaborating during the COVID-19 pandemic. Success factors for collaborating with new and existing partners without face-to-face meetings included laboratory capacity and experience with analytical methods, study objectives that were relevant for the partner and locality, and a strong quality assurance plan to ensure comparability of results. The lessons learned can be taken forward as ways to reduce carbon footprint, and contribute to resilient, inclusive development research projects.

Urban Sanitation: New Terminology for Globally Relevant Solutions?

“…This is misleading, because when wastewater includes water from pour-or cistern-flush toilets, in addition to cleansing, bathing, cooking, food waste, and rubbish, it is typically <5% total solids. 34,25 It is also a misconception that "fecal sludge" is from only households, and global statistics on sanitation coverage are limited to households, schools, and healthcare facilities. 4 However, a majority of people spend most of their waking time outside the household where they sleep at night, and in urban areas of low-income countries, a majority of meals are eaten on the street.…”

“…By contrast, in urban areas, with very different usage patterns, the filling rates are much higher and the pits require frequent emptying with transport to treatment, as there is no land available to dig a second pit when they become full. Wastewater that accumulates in onsite containment varies from 10 to >1000 L per person per day, , with the amount that is contained and accumulates being much smaller than the total produced. Accumulation rates are so variable due to the range of onsite containment technologies, retention times, differences in household and commercial usage patterns, quality of construction, and collection practices …”

“…In this case, what is normally termed wastewater when it flows in a sewer is suddenly renamed as “fecal sludge”. This is misleading, because when wastewater includes water from pour- or cistern-flush toilets, in addition to cleansing, bathing, cooking, food waste, and rubbish, it is typically <5% total solids. , …”

Fecal Sludge Recycling to Useful Products: Environmental Concerns, Viability and Potential

“…Also, the absence of enough electric vehicle charging station in Bangladesh can be resolved by generating electricity through biogas for electric vehicles charging by employing MSW and HE (Alam et al, 2021). Limited adoption of the biogas system for treating FS will be a thing of the past, if a viable market and business models along the FS management service chain right from toilet provision to emptying/collection and transport to treatment and reuse are developed (Andriessen et al, 2023;Blackett et al, 2014;Harper et al, 2018;Odey et al, 2019). The model must therefore encompass, septage collection vehicle and safety equipment to protect against poisonous gas formation/exposure during clearance as well as a legal enforcement of operating guidelines of septage collection to address overflow and leakages which pollutes the environment (Pasi, 2022).…”