Food waste reduction strategies in composting and recycling centers based on material flow analysis

BACKGROUND AND OBJECTIVES: Food waste has major environmental, economic, and social impacts, contributing to greenhouse gas emissions, soil depletion, global food insecurity, and rising food prices. Addressing the global challenge of food waste necessitates a heightened focus on food waste treatment. This investigation analyzed the extent of food waste reduction achieved at composting and recycling centers in Surabaya. The objective of this study is to evaluate the effectiveness of food waste reduction at composting and recycling facilities. METHODS: The study utilized material flow analysis to assess food waste reduction at the Wonorejo composting and the Jambangan recycling centers. The present analysis examines the quantity and dynamics of food waste, starting with i) the pre-treatment stage that encompasses sorting, shredding, and sieving; ii) the composting process, which involves the generation of compost and the loss of water; and finally, iii) the bioconversion process facilitated by black soldier fly larvae, highlighting the production of larvae biomass and frass. FINDINGS: At the Wonorejo composting and Jambangan recycling centers, composting served as the main approach for the treatment of food waste. At the Wonorejo composting center, over 99 percent of food waste was composted, whereas 0.22 percent was managed through black soldier fly larvae bioconversion. Within this composting center, the conversion rates revealed that 70.71 percent of the food waste was processed into mature compost. Furthermore, 0.03 percent was utilized for larval biomass production, 24.94 percent was lost to moisture, and 4.32 percent remained as residual waste. At the Jambangan recycling center, 85.74 percent of food waste was composted, whereas the remaining 14.26 percent was handled through black soldier fly larva bioconversion. Approximately 40.03 percent was transformed into mature compost, 1.37 percent into larval biomass, 29.26 percent lost as moisture, and the remaining 29.34 percent was landfilled. CONCLUSION: Material flow analysis revealed that compost and recycling center facilities preferred composting over black soldier fly larva bioconversion for food waste reduction. Composting proved to be an effective method for processing over 85 to 99 percent of food waste, while the application of black soldier fly larvae bioconversion resulted in a mere 0.2 to 14 percent of food waste being treated. In light of the significant volume of food waste that continues to be disposed of in landfills, it is imperative for the Surabaya City Government to establish additional composting facilities in various locations. Furthermore, the implementation of supplementary strategies, including the management of surplus food distribution and the encouragement of composting at the household level, is essential for enhancing food waste management throughout the supply chains.