Biodegradation of High Cellulose-Lignin Content Agricultural Wastes in Bioreactors

The bioreactor landfill is a solid waste disposal method that provides rapid solid waste degradation and acquisition of methane. Bioreactors in which leachate circulation is carried out are generally operated anaerobically. The biodegradation of wastes with high lignin and cellulose content is very difficult. Especially under anaerobic conditions (moreover, if there is a lack of moisture), such wastes almost never decompose. In this study, the degradation of the waste sunflower stalks that are difficult to biodegrade and have a high lignin-cellulose content and the production of methane gas in semi-aerobic bioreactors have been investigated. Sunflower stalk, were loaded into the bioreactors in different proportions and mixed with the organic fraction of municipal solid waste (OFSWM). The bioreactors were operated under different operating conditions. The contents of cellulose, hemicellulose, lignin, and initial and final organic matter in the wastes loaded into the bioreactors were examined. Parameters such as pH, COD, BOD5, TKN, NH4-N in leachate were analyzed, and the amounts of total and methane gas were measured. Initially, all bioreactors were operated anaerobically. In the decomposition of the sunflower stalk, while 43% of the organic matter removal was achieved in the anaerobic bioreactor, 60% of the organic matter removal was realised in the semi-aerobic/anaerobic bioreactor. Thereupon, other agricultural wastes were subjected to decomposition under semi-aerobic/anaerobic operating conditions. As a result of the study, it can be said that semi-aerobic pretreatment accelerates the breakdown of agricultural wastes with high lignin and cellulose content, decreases the COD values of leachate, and increases the amount of methane.