Drying of fecal sludge in 3D laminate enclosures for urban waste management

Abstract

Laminated hydrophobic membranes have been proposed as liners for container-based sanitation systems in developing countries. The laminate allows drying of fecal sludge, which might significantly reduce the frequency of container emptying, while containing liquids and solids. While previous laboratory tests demonstrated rapid drying of fecal sludge or water retained in laminates, experiments did not assess the effects of system dimension or scale on performance. In this study fecal sludge drying and water evaporation were evaluated in 3D laminate boxes (decimeter scale) or 3D laminate-lined 40 L and 55 gallon drums (meter scale) that are prototypes of toilet containers for field application. A stagnant film model described fecal sludge drying and water evaporation in the laminate boxes and laminate-lined drums well. The effective diffusion length ( λ ) for the laminate was fitted in all systems and increased with system dimension and scale: λ increased by a factor of 1.4 from 1D decimeter-scale envelopes to 3D decimeter-scale boxes, and by a factor of 1.3–1.7 from 3D decimeter-scale boxes to 3D meter-scale drums. The longer λ with increasing dimension and scale is likely due to nonuniform temperature and relative humidity in the air outside the laminate and nonuniform temperature within the laminate. Using best-fit λ for the laminate-lined 40 L and 55 gallon drum experiments conducted in a controlled laboratory, drying was predicted for an 11-day field experiment. Although the air temperature and relative humidity varied significantly in the field tests from −1 °C to 26 °C and 35% to 97%, respectively, the stagnant film model predicted drying over the 11-day period reasonably well with total error ≤ 13% using 24-h average air temperature and relative humidity. Drying of fecal sludge in laminate-lined drums in the field might be adequately described with a stagnant film model using daily-average weather conditions, if wind speeds are low.

Validation of an Instrument to measure the acceptance of a technology for the self-removal of human excreta adapted to Dry Toilets

“…Para diseñar los componentes apropiados propuestos para este diseño, tomamos como referencia resultados ya desarrollados [15], en el que proponen14 ítems o preguntas para diseñar un instrumento de medición altamente eficiente en la validación de un cuestionario para medir las competencias culturales en trabajadores en salud pública. Se revisó la literatura en el área de las tecnologías de reducción de lodos fecales aplicadas a Inodoros secos y sus respectivos instrumentos de medición publicados previamente [2], [3] y [4]. Así también se consideró los resultados obtenidos [16], puesto que se utilizó el análisis factorial exploratorio con 06 componentes para determinar la satisfacción de los usuarios con respecto a un servicio médico obteniendo altos valores de confiabilidad.…”

“…Desde que apareció el inodoro seco [1], se han ido mejorando a través del tiempo su diseño formal, su funcionamiento y también la percepción que los usuarios tienen de su eficiencia. Existen actualmente prototipos de inodoro seco con mayores ventajas técnicas, las cuales van desde el diseño formal hasta metodologías innovadoras como deshidratación por calentamiento e inmovilización de lodos fecales [2], [3] y [4]. El objetivo de esta investigación es construir un instrumento que permita medir la aceptación de la población hacia una tecnología de eliminación de excretas humanas por auto-remoción adaptada al inodoro seco con separador de orina.…”

A lab-scale study on the influence of the compost-dewatering process on moisture removal and pathogen inactivation in pre-sanitized fecal sludge

“…Fecal sludge management (FSM) is a serious environmental issue that needs awareness and will play a key role in the management of future sanitation issues (Saxena et al 2019). Onsite treatment technologies are usually viewed as temporary solutions until a permanent adequate system can be constructed (Penn et al 2018).…”

Municipal Waste Management in the European Union

“…Due to urban development, there is a need for proper sanitation systems in cities (Burlacu et al, 2020). Thus, the importance of waste management increases (Saxena et al, 2019). Knowledge of the factors that influence waste collection is a component of waste management (Bran et al, 2020).…”