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Pilot-scale composting of typical multiple agricultural wastes: Parameter optimization and mechanisms

Bian, Bo, Hu, Xiuren, Zhang, Shaopeng, Lv, Chengxu, Yang, Zhen, Yang, Weiben, Zhang, Limin
Bioresource technology 2019 v.287 pp. 121482
carbon, carbon nitrogen ratio, composting, composts, leaves, organic matter, particle size, poultry manure, rice hulls, vegetables
In this work, pilot-scale (100 kg of mixed wastes each time) composting of typical agricultural wastes, including chicken manure, vegetable leaves and rice husks with a mass ratio of 6:3:1, was studied. Effects of thermal phases and transformation time on performance, including moisture, nutrient, and carbon contents and C/N ratios of compost, were investigated. The optimal parameters were 75 ± 5 °C and 18 h; the compost met the requirements of Chinese National Agricultural Organic Fertilizer Standard (NY525-2012). Mechanisms investigations demonstrated that, Bacillus and Sinibacillus played key roles in degrading high-molecular-weighted organic substances into small-molecular-weighted humic- and fulvic-acid-like matters, resulting in smaller particle size and loose structure of the product; rice husk particles acted as a conditioning agent and remained their originally morphology. The mechanism provided informative guidance for optimizing the process in practical application.