Changes of organic matter content during aerobic co-composting of sewage sludge with straw

【Objective】Changes of organic matter content during aerobic co-composting of sewage sluge with straw were studied to provide reference for the improvement of the efficiency and quality of the sewage sludge compost fertilizer.【Method】Aerobic co-composting of sewage sludge mixed with wheat straw and maize straw,lasting 35 d,was carried out.Wheat straw bran(d5 mm),wheat straw chip(3 cmd5 cm),maize straw bran(d5 mm) and maize straw chip(3 cmd5 cm) were amendments in treatment 1～4 respectively.The following parameters were measured at different composting stages:total organic carbon(TOC),dissolved organic carbon(DOC),humic substances content(humic and fulvic acid),H/F and fiber.The role and relevance of DOC,H/F and temperature,used as parameters of compost maturity,were analyzed.【Result】TOC decreased during composting process constantly,Dec of TOC reached 31.30%,27.09%,54.87% and 48.97% respectively;DOC concentration declined to 9.48,7.15,9.10 and 11.07 g/kg gradually;humus content didn't increase significantly;H/F,increased to 1.54,2.21,1.56 and 1.90 respectively in the four treatments;Fiber was degraded slowly.【Conclusion】The results showed Maize straw bran is the best amendment in composting.H/F,temperature and dissolved organic carbon can be used as indicators of compost maturity.