Chinese medicinal herbal residues as a bulking agent for food waste composting

This study aimed to co-compost Chinese medicinal herbal residues (CMHRs) as the bulking agent with food waste (FW) to develop a high value antipathogenic compost. The FW, sawdust (SD) and CMHRs were mixed at three different mixing ratios, 5: 5: 1, 2: 2: 1 and 1: 1: 1 on dry weight basis. Lime at 2.25% was added to the composting mix to buffer the pH during the composting. A control without lime addition was also included. The mixtures were composted in 20-L in-vessel composters for 56 days. A maximum of 67.2% organic decomposition was achieved with 1: 1: 1 mixing ratio within 8 weeks. The seed germination index was 157.2% in 1: 1: 1 mixing ratio, while other ratios showed < 130.0% and the treatment without lime showed 40.3%. Therefore use of CMHRs as the bulking agent to compost food waste at the dry weight ratio of 1: 1: 1 (FW: SD: CMHRs) was recommended for FW-CMHRs composting.