Food waste and montmorillonite contribute to the enhancement of green waste composting

Abstract

Composting is currently the best strategy to dispose of green waste (GW) containing substantial quantities of lignocelluloses that prolongs composting time and yields unstable compost. This study aimed to evaluate the effects of food waste (FW, at 0%, 35%, and 55%) and montmorillonite (M, at 0%, 10.5%, and 15.5%) as the composting amendments on the physicochemical and microbial characteristics of compost in two-stage composting of GW. Changes in temperature, bulk density, C/N ratio, carbon dioxide emission, organic matter, humic substances, lignocellulosic substances, microbial numbers, and phytotoxicity were assessed during GW composting. The results demonstrated that combining FW and M exhibited positive effects, and 35% FW and 15.5% M obtained the best results in all compost characteristics. The optimum extended thermophilic period, enhanced lignocellulose decomposition, and generated a stable and mature product in only 21 days. Consequently, the best final compost was mature (C/N ratio: 7.01, HAs/FAs ratio: 3.14, and NH4+-N/NO3–-N ratio: 0.10), nutrient-rich (N: 4.89%, P: 2.01%, and K: 0.92%), and no phytotoxic (germination index: 145%). This study unveils the effects of FW, M, or a combination of FW and M on compost characteristics. The study therefore increases the understanding of the sustainable disposal of an important solid waste.