Co-composting of livestock manure with rice straw: Characterization and establishment of maturity evaluation system

• Published in: Waste management (Elmsford) 2014-02, Vol.34 (2), p.530-535
• Main Authors: Qian, Xiaoyong, Shen, Genxiang, Wang, Zhenqi, Guo, Chunxia, Liu, Yangqing, Lei, Zhongfang, Zhang, Zhenya
• Format: Article
• Language: English
• Subjects: Animals; Applied sciences; Co-composting; Dairy manure; Exact sciences and technology; Hydrogen-Ion Concentration; Kinetics; Livestock; Manure - microbiology; Maturity evaluation index system; Nitrogen - analysis; Oryza; Other wastes and particular components of wastes; Plant Stems - microbiology; Pollution; Rice straw; Soil - chemistry; Species Specificity; Swine manure; Temperature; Wastes
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2013.10.007

•The maturation process of co-composting of livestock manures and rice straw was characterized.•Swine manure exhibited faster maturation than dairy manure when co-composted with rice straw.•A comprehensive maturity evaluation index system including C/N ratio, GI and PGI was established.•GI>120% and PGI>1.00 signal mature composts from livestock manure and rice straw. Composting is considered to be a primary treatment method for livestock manure and rice straw, and high degree of maturity is a prerequisite for safe land application of the composting products. In this study pilot-scale experiments were carried out to characterize the co-composting process of livestock manure with rice straw, as well as to establish a maturity evaluation index system for the composts obtained. Two pilot composting piles with different feedstocks were conducted for 3months: (1) swine manure and rice straw (SM–RS); and (2) dairy manure and rice straw (DM–RS). During the composting process, parameters including temperature, moisture, pH, total organic carbon (TOC), organic matter (OM), different forms of nitrogen (total, ammonia and nitrate), and humification index (humic acid and fulvic acid) were monitored in addition to germination index (GI), plant growth index (PGI) and Solvita maturity index. OM loss followed the first-order kinetic model in both piles, and a slightly faster OM mineralization was achieved in the SM–RS pile. Also, the SM–RS pile exhibited slightly better performance than the DM–RS according to the evolutions of temperature, OM degradation, GI and PGI. The C/N ratio, GI and PGI could be included in the maturity evaluation index system in which GI>120% and PGI>1.00 signal mature co-composts.