Measurement and Modelling of Moisture Sorption Isotherm and Heat of Sorption of Fresh Feces

Abstract

The drying (or dewatering) of fresh feces and fecal sludge is a productive step in the management of sanitation, waste treatment, and resource recovery services. An improved understanding of fresh feces and fecal sludge drying would contribute to the development and deployment of fecal sludge management services. However, there is a lack of available literature on the fundamental drying characteristics of fresh feces. In response to this gap, this work shares experimental results for equilibrium moisture content of fresh feces at different water activity levels (aw) and proposes the use of the Guggenheim, Anderson, and de Boer (GAB) model for predicting aw, calculating the heat of sorption, and estimating the corresponding energy requirements for drying of fresh feces. This is the first time this work has been done with fresh feces. The total heat of evaporation was significant up to a moisture content of about 0.2 kg water per kg dry solids. In addition to informing drying process design, the sorption isotherm can be used to predict microbial activity, which could improve the management of feces and fecal sludge from a public health perspective. These data in turn will be used to promote access to dignified, safe, and sustainable sanitation.

Synthesis of Activated Carbon from Agricultural Wastes and Its Application in Adsorption of Dyes

“…where C e is the equilibrium aqueous phase concentration of adsorbate (mg L −1 ), q e is the equilibrium adsorbent phase concentration of adsorbate (mg L −1 ), q o is the adsorption capacity (mg g −1 ), and b is the constant related to the free adsorption energy and the reciprocal of the concentration at which half saturation of the adsorbent is reached (L mg −1 ) 21, 23–25, 35, 37–39.…”

“…This crucible was put into an oven at 105 °C for 2 h. The variance between the initial mass ( m i ) and final mass ( m f ) of samples represents the moisture content according to Eq. 1 23. …”

Hygrothermal performance of cool roofs with reflective coating material subjected to hot, humid and dusty climate

“…Additionally, for most porous materials, there is hysteresis between the adsorption and desorption isotherms. Due to the complexity of sorption processes, the isotherms cannot be determined explicitly by calculation, but must be measured experimentally for each porous material (e.g., see Kumaran et al, 2004;Mukhopadhyaya et al, 2007;Remington et al, 2020). For a given water content value, the sorption isotherm provides the corresponding RH value.…”

In situ treatment technologies for pit latrines to mitigate groundwater contamination by fecal pathogens: a review of recent technical advances

“…However, the study did not check for pathogen retention or die-off inside the laminate-lined container. Since most pathogenic bacteria are inactivated by moisture reduction to a threshold water activity (Remington et al 2020), pit latrines with commercial hydrophobic laminate liners have been proposed in order to mitigate fecal contamination of groundwater (Figure 2).…”