紫外耦合游离亚硝酸强化剩余污泥厌氧发酵产酸研究

Enhancement of acidification from waste activated sludge via anaerobic fermentation by free nitrous acid(FNA)pretreatment assisted by ultraviolet

为打破传统厌氧发酵过程中污泥破壁溶胞困难和产酸效能低的瓶颈,探究了紫外光(UV)耦合游离亚硝酸(FNA)预处理对污泥发酵产酸的影响,并与热(H)和超声法(US)耦合FNA预处理进行了对比分析.结果表明,UV辅助FNA联合预处理(FNA-UV)对细胞破碎和胞外聚合物的剥离具有协同效应,･OH和･O_(2)^(-)作为反应中间体,其强度远高于其他预处理组(FNA-US和FNA-H),与･NO,･NO_(2)及ONOO^(-)等中间产物共同促进了溶解性有机物的释放,溶解性碳水化合物和蛋白质含量相比FNA组分别提升60%和90%,进而为后续水解产酸过程提供了充足的底物.FNA-UV组短链脂肪酸(SCFAs)浓度于第4d达到峰值,为(201.8±4.8)mg COD/g VSS,相比FNA组提升67%,乙酸占比高达56.8%.通过发酵末期对各体系进行碳平衡分析表明,紫外耦合FNA预处理在污泥减量、溶解性有机物的释放与转化、SCFAs的产生方面具有重要作用.微生物群落分析表明,FNA-UV对功能菌群的富集发挥重要作用,表现为厌氧发酵菌和反硝化菌的有效增强,相比其他各组提升了23.7%~270.6%.

In order to break the bottleneck of the limited hydrolysis performance and low short chain fatty acids(SCFAs)production efficiency from waste activated sludge(WAS)during the traditional anaerobic fermentation,this work investigated the effect of the ultraviolet(UV)assisted free nitrous acid(FNA)pretreatment on WAS disintegration and acidification,and compared with thermal(H)and ultrasonic(US)coupled with FNA pretreatment.Results revealed that UV assisted FNA co-pretreatment(FNA-UV)had a synergistic effect on disruption of both extracellular polymeric substances and cell envelope.･OH and･O_(2)^(-),as the main reaction intermediates,their intensities in FNA-UV group were much stronger than that obtained in other pretreatment groups(FNA-US and FNA-H).Moreover,these two free radicals,with the intermediates such as･NO,･NO_(2)and ONOO^(-),further promoting the release of soluble organics.The contents of soluble carbohydrates and protein were 60%and 90%higher than that obtained in FNA group respectively,which served more soluble substrates for SCFAs generation.Accordingly,SCFAs concentration peaked at 4d in FNA-UV group(201.8±4.8)mg COD/g VSS with 56.8%acetic acid(HAc)),which was 67%higher than that of FNA group.Carbon balance analysis at the final stage of the fermentation showed that UV assisted FNA pretreatment played an important role in sludge reduction,release and transformation of soluble substrates,and finally SCFAs production.The functional microbial consortia analysis indicated the anaerobic fermentation bacteria and nitrate-reducing bacteria were obviously enriched in FNA-UV group,which were 23.7%~270.6%higher than that obtained in other groups.