挥发性有机酸对餐厨垃圾产沼气过程中胞外多聚物影响研究

Effects of Volatile Fatty Acids on Extracellular Polymeric Substances (EPS) During the Biogas Process From Food Wastes

餐厨垃圾的厌氧消化处置被认为是一种高效环保的技术,在减量化的同时还能产生沼气。然而由于餐厨垃圾自身较高的有机物含量,会造成反应体系挥发性有机酸的大量累积,严重抑制产甲烷活性。胞外多聚物作为微生物分泌到胞外的活性物质,其含量和组成会因挥发性有机酸积累导致的反应环境变化而变化明显。实验结果表明:随着物料负荷的升高,反应体系乙酸累积量增加,最高达到17.93 g/L。不同物料负荷下,胞外多聚物总量在反应进行过程中变化不明显,然而主要成分多糖和蛋白质的比例变化较大。反应后期蛋白质质量分数增加,其中S2组蛋白质质量分数最高达到0.038 mg/g,这可能是微生物响应高浓度乙酸环境,缓解挥发性有机酸毒害所引起的。3种类型的胞外多聚物组成随物料负荷的增加变化不同。溶解型和疏松型多糖/蛋白质比例随物料负荷变化明显,12 h时SMP和LB-EPS变化幅度达到70.2%和74.7%,而紧密型多糖/蛋白质比例较为稳定。

Anaerobic digestion is considered to be an efficient way of disposing food wastes,which can not only reduce waste amounts,but also produce biogas. However,the excessive accumulation of volatile fatty acids（VFA） caused by the high organic loads will inhibit anaerobic digestion intensively. Extracellular polymeric substances which are secreted by the microbes,are considered to be influenced intensively on content and composition with the changing of reaction conditions.The results indicated that the amount of acetic acid increased with the increasing of organic load,which achieved by the maximum concentration by 17.93 g/L. There were few impacts on the EPS total amounts in the reaction systems with different organic load. However,the proportions of polysaccharide and protein were changed obviously. The concentration of protein increased at the end of reaction,and obtained maximum value of 0.038 mg/g in S2,which was possiblely due to the response to toxic under high acetic acid concentration conditions.. The trends of proportions between polysaccharide and protein in three EPS types were different. The proportions in soluble microbial products（SMP） and loosely bound EPS（LB-EPS） changed apparently,which reached by 70.2% and74.7%,respectively,of the low values at the 12 h hour,However,the proportion in tightly bound EPS（TB-EPS） kept stable.