Synergistic Composting of Urban and Rural Multi-Source Organic Waste and Product Quality Evaluation: A Case Study of a Treatment Center in the Taihu Lake Region

• • The coupled bio-drying and aerobic composting process reduced kitchen waste moisture from 77.70% to 58.69% after 1 day of bio-drying, and further to 23.22% after 7 days of silo reactor composting, demonstrating rapid dewatering efficiency critical for high-moisture waste streams. • • Aerobic composting achieved a peak temperature of 68.1°C with >55°C sustained for over 5 days, satisfying the harmless treatment requirements of CJJ 52—2014, ensuring pathogen reduction. • • After 20 days of maturation, the product met NY/T 525—2021 standards: organic matter 51.22%, total nutrients 5.61%, EC <4.00 mS·cm−1, and heavy metals (As 0.23 mg/kg, Hg 0.05 mg/kg, Pb 13.92 mg/kg, Cr 44.28 mg/kg, Cd 0.30 mg/kg) all below regulatory limits. • • High recycle ratios of compost return caused salt accumulation, inhibiting microbial activity and delaying maturation, highlighting the need for optimized bulking agent strategies to balance salinity and structure.