Research On The Effect Of Pretreatment On Anaerobic Digestion Of Straw

Anaerobic digestion technology has been used widely as an ideal solid organic waste disposal way in recent years. The anaerobic digestion of solid organic waste is a very intricate biochemical process which is imposed by many factors, especially to the property of solid organic waste. Under the same technologic condition, the results of anaerobic digestion are very different with the variety of property. For the solid organic waste containing many fibrin, the efficiency of anaerobic digestion and the gas yield are very low. So, optimizing the anaerobic digestion by pretreatment of solid organic waste has become a very important problem. In this research, the straw with high fibrin content was pretreated by various physical and chemical pretreatments that based on domestic and overseas researches, and the results of anaerobic digestion were analyzed after a complete-mixing anaerobic digestion.It's very obvious that pretreatments can improve the anaerobic digestion of straw based on the results experiments. Solutions of NaOH in different concentration were used to pretreatment the straw. The results showed that: the biogas yield was increased 38.4%～119.2% , the methane content was increased from 46.3% to 59.4% and VS removal rate was improved from 38.3% to 51.1%.As the size of straw reduced from 50mm to 20mm and 10mm by mechanical chop, the biogas yield was increased respectively 37.5% and 47.4%, and the methane content was increased respectively from 43.1% to 46.5% and 44.9%1, and VS removal ratio was improved respectively from 30.6% to 40.2% and 39.3%. Under the same size, the biogas yield of the straw after mechanical grinding was increased 55.9% comparing with the straw only chopped, and the methane content was increased from 46.5% to 51.2%, and VS removal ratio was improved from 40.2% to 49.6% .After the thermal pretreatment at 60℃, 80℃ and 100℃, the biogas yield was increased respectively 61.5%, 90.3% and 121.5% comparing with 20℃, and the methane content was increased respectively from 42.1% to 45.9%, 48.6%1 and 51.5%, and VS removal ratio was improved respectively from 38,6% to 40.3% and 47.2% and 58.3%.The biogas yield was increased 61.9% with the increase of inoculum, and the methane content was increased from 33.5% to 46.1%, and VS removal ratio was improved from 29.3% to47.8%.