MBR中污泥的内源消化性能及EPS转化特征解析

Variation characteristics of EPS and endogenous digestion performance of surplus sludge from MBR process

膜生物反应器(MBR)具有污泥产量少等众多优点,同时也存在着污泥沉降性能及脱水性能差、剩余污泥难于处理的问题.为此,采用2种生物技术(好氧消化和好氧/缺氧消化)处理MBR工艺剩余污泥,研究污泥的内源消化性能及胞外聚合物(EPS)的转化特征.结果表明:在常温条件下,好氧/缺氧消化20d时MLVSS降解率可达到50%,比好氧速率(SOUR)降低到1.5mgO2/gMLVSS·h以下,完全能够满足污泥稳定处理的要求,同时比好氧消化节约曝气能耗.EPS的组分化学分析发现污泥消化后EPS中蛋白质、多糖和DNA的含量明显增加,表明消化过程中活性污泥的裂解导致胞内物质的释放,促进了EPS含量的增加与转化.同时,红外光谱、三维荧光光谱及凝胶渗透色谱的分析结果认为,溶解性胞外聚合物(SEPS)与结合性胞外聚合物(BEPS)均以蛋白质、多糖、富里酸和腐植酸等组成,随着污泥的消化,BEPS增加且逐渐转化为SEPS,并导致类富里酸、类腐植酸等难降解有机物的积累和类蛋白质的降解;污泥消化前后SEPS分子量分布变化明显,呈现分子量减小的趋势,而BEPS分子量分布范围变化不大,主要表现为有机物浓度的显著增加.

MBRs show many advantages over conventional activated sludge system, including less excess sludgeproduction, but also face some problems, such as hard to dispose of the surplus sludge due to its poor settling anddewatering ability. With this in mind, two sludge treatment technologies, namely aerobic digestion reactor andaerobic/anoxic intermittent digestion reactor were applied for the digestion of sludge from the MBR system toinvestigate the performance of the biological digestion processes and EPS variation characteristics during batchtests. The results indicated MLVSS removal efficiency could reach 50% and SOUR （specific oxygen utilizationrate） decreased to below 1.5 mg/g. h after 20 days~ aerobic/anoxic digestion, which meant that the aerobic/anoxicdigestion could meet the requirement of sludge stabilization and save more energy cost compared to aerobicdigestion. Through chemical analysis of EPS components content, it was found that the content of proteins,polysaccharides and DNA showed significant increase, indicating large amount of biomass decay and the release ofcellular substances after sludge digestion. The infrared spectroscopy （IR）, three dimensional excitation-emissionmatrix （EEM） fluorescence spectroscopy and gel permeate chromatography （GPC） were used to characterize EPS.SEPS and BEPS both consisted of proteins, polysaccharides, fulvic acid and humic acid. With the digestion ofsludge and cell lysis, BEPS increased and transformed to SEPS, which induced the accumulation of fulvic acid andhumic acid and the degradation of proteins. After digestion, the change of molecular weight distribution of SEPSwas more obviously than BEPS, and the molecular weight of SEPS showed a decrease tendency.