Evaluation of different natural additives effects on the composting process of source separated feces in resource-oriented sanitation systems

Abstract

In most resource-oriented sanitation (ROS) systems, the composting process has been a sustainable treatment method for source separated feces. Nonetheless, a slow and low degradation efficiency—combined with hygienic concerns, especially for the high amount of waste produced —makes the selection of the composting bulk additives a critical decision for the process. This study presents the efficiency improvement of adding different natural additives to enhance the composting process of the source separated feces in ROS systems. Three different natural additives, including sawdust, rice husk, and rice husk charcoal were utilized for the composting process of fresh feces with an additive w/w ratio of 2:1. To evaluate the impact of additives on compost properties, chemical, physical, and biological characteristics of composting materials were measured. Results indicated that using rice husk charcoal as an additive of the process was effective and generated a degradation of more than 40% of total organic carbon (TOC), reduced the nitrogen loss to less than 0.2%, and improved the germination index (GI) to more than 80%. Moreover, in terms of fecal indicators, the Escherichia coli (E. coli) stains were totally removed after five weeks. The efficacy of utilizing rice husk charcoal as a composting matrix in resource oriented sanitation systems can be, therefore, demonstrated as a nature-based treatment for source separated feces.