Evaluation of new small-scale composting practices with energy recovery

Abstract

This study involves the evaluation of new composting systems for the treatment of organic solid waste (OSW) that has low environmental impact. Two composting de-vices were developed, with four types of management, and their behavior was analyz-ed regarding temperature, gas production, moisture, leachate and percolated water production, compost maturation, nutrient presence, pH and water heating, which can be seen as an energy gain in addition to the economic viability of the process. The proposed composting techniques kept the waste at thermophilic temperatures for more than 20 days, with no significant emission of CH4, under aerobic conditions by passive aeration, without leachate generation. These results can be partially attribut-ed to the suspension of the compost on pallets, the residue composition chosen in the experiments and the boundary conditions of the compartments. The energy recovery test, through water recirculation inside the compost, presented temperatures that reached 51°C after 24 h of recirculation, and were maintained throughout the process, 20 days, demonstrating its effectiveness. The proposed composting mod-els are environmentally viable, minimizing gas emissions and leachate generation compared to landfill or industrial composting plants. They can be used in industrial kitchens, residential complexes, shopping malls and other small and medium solid waste generators. In addition, the solution presented in this study avoids the trans-portation of waste over medium and long distances, which also brings a significant reduction in energy expenses, and in the case of landfills, it avoids occupation for long periods, thus reducing emissions of gases and leachate, whose control and treatment are expensive.