On site composting of food waste: A pilot scale case study in China

Abstract

Composting is one of the effective strategies to treat excessive amount of food waste (FW). In this study, the mode of source separation by residents – composting in situ with complete equipment (CPEM) was proposed. Pilot scale facility covering 132 m2 was constructed and operated to treat FW (6 t/d). Results showed that the composting CPEM including feeding, breaking, dewatering, spiral boosting, composting reactor, odor biofilter, aeration system, and rotating device units was operated stably over two years. During 10 days drum composting, the temperature of FW experienced three classic phases including heating phase, thermophilic phase, and cooling phase. The concentration of H2S and NH3 in the effluent were as low as 0.0001 and 0.025 mg/m3 after biofiltering treatment. After 20 days subsequent post-maturity, total content of N, P and K in the FW compost was as high as 11.66%. When the compost was applied to pakchoi (Brassica chinensis L.), the content of vitamin C and soluble sugar increased 18.78% and 38.49%, and the content of nitrate and nitrite decreased 46.86% and 51.89%, respectively. As for economical consideration, the average investment and energy consumption of the CPEM were as low as US$ 61.5 and 50.0 kWh/t. The successful case of the pilot scale plant suggested that the mode of source separation-composting in situ with CPEM was feasible to realize the recycling of FW.