Exploring the limits for achieving pathogen inactivation temperatures in small-volume container-based feces composting

ABSTRACT

Conceptual overview of the study. Carbon-to-nitrogen ratio and moisture content are experimentally investigated using a simple insulated compost reactor with forced aeration and temperature monitoring. Experimental results are used to simplify an analytical composting model, which is then applied to define the operational space for achieving pathogen-inactivation temperatures in container-based feces composting systems.

Decentralized technologies, such as dry toilets with feedstock composting, can help alleviate sanitation needs in resource-constrained environments. Using container-based composting systems, this work demonstrates the technical feasibility of achieving pathogen-inactivation temperatures in simple container-based composting systems and provides a framework for identifying operating conditions that support thermophilic composting. Based on an accessible analytical model, this work experimentally explores the influence of the parameters of moisture content (MC) and carbon-to-nitrogen ratio on the compost temperature. The effect of MC on the slope of the initial temperature rise can be explained by an increase in the specific heat capacity of the compost, but the effects of the carbon-to-nitrogen ratio were inconclusive within the useful range for household-scale composting. Given the experimental results, a simplified version of the original model was used to define an operational space for achieving pathogen-inactivation temperatures and help guide the design of household-scale, container-based systems for feces composting.