Effect of Bulking Agent on Composting and Greenhouse Gas (GHG) Emissions of Organic Fraction of Municipal Solid Waste

Abstract

Solid waste generation is increasing day by day globally. Similarly, in Pakistan more than 50% of the municipal solid waste is biodegradable and contributes to greenhouse gas (GHG) emissions if not managed properly. To address this issue there’s a need to use a waste management technique that is economically feasible, environmentally friendly, and practically possible. Composting of organic fraction of municipal solid waste is one of the promising techniques for converting waste into a resource. This study was aimed to convert waste (organic fraction of municipal solid waste) into a resource (compost) using three different bulking agents (wood shavings, dry leaves, and corn stalks) in three different reactors. The composting mixture was monitored for its characteristics like temperature, moisture content, TS, VS, TOC, TKN, C/N ratio, TP, and pH. Secondly, the GHG emission potential of compost was determined at different stages of compost formation. The final compost using three different bulking agents had C/N ratio of 20.6, 15 and 12.4 for wood shavings, dry leaves, and corn stalks respectively that is considered an ideal value for mature and stable compost. The results of GHG emission potential showed that raw waste had maximum GHG potential of 3114, 2926 and 2833 g CO₂eq/kg compost for wood shavings, dry leaves and corn stalks respectively as compared to final compost having GHG emission potential of 934, 832 and 736 g CO₂eq/kg compost for wood shavings, dry leaves and corn stalks respectively. Moreover, the net GHG emissions were found to be minimum and almost similar for all the three bulking agents in the final compost. Together, the results showed that composting of waste with bulking agents can produce a stable compost and can significantly reduce the GHG emissions.