Composting food and fishery waste: a feasibility study on system performance and microbial inoculation

Abstract

This study investigates the composting processes for organic waste derived from food and fishery sources, focusing on the feasibility and performance of in-vessel (IV) and static pile (SP) systems for potential application in remote or resource-limited small communities. The research lies in its integrated evaluation of mature compost inoculation effects within an in-vessel system treating a high proportion of fishery waste (13% by weight), a feedstock combination rarely studied under controlled reactor conditions. Given the challenges posed by high moisture and nitrogen contents in such wastes, the research evaluates the effectiveness of mature compost inoculation in enhancing microbial activity, accelerating organic matter degradation, and improving compost quality. Experimental trials involving the use of IV composting reactors, with and without mature compost inoculation, and their comparison with SP composting demonstrated that the IV system with microbial inoculation sustained thermophilic conditions for seven consecutive days and achieved a 44% reduction in the carbon-to-nitrogen ratio. The germination index increased from 20% at the beginning of the process to 260% by the end, indicating excellent compost maturity. Enzyme activity analysis further supported these findings, with β-glucosidase and dehydrogenase levels in the IV system exceeding those in the SP system by 32% and 26%, respectively. Acidic and alkaline phosphatase activities were also consistently higher in the IV system. These advantages highlight the superior decomposition rate, pathogen inactivation potential, and nutrient stabilization offered by the IV system compared to traditional SP composting. Additionally, the study evaluated the operational performance of an IV composting reactor equipped with an axial mixer, demonstrating its potential for efficient waste treatment in remote or resource-limited settings. The findings provide practical applications for decentralized organic waste management in small northern or rural communities and the industrial, commercial, and institutional sectors, enabling environmentally friendly waste diversion, reduced landfill dependency, and production of high-quality compost for agricultural or land restoration use. Overall, the results confirm that combining controlled composting conditions with microbial inoculation significantly enhances process efficiency, compost stability, and product quality, supporting the adoption of IV systems as a sustainable solution for managing organic waste generated by the Industrial, Commercial, and Institutional sector and in small and remote communities.