Effects of solution conditions on the physicochemical properties of stratification components of extracellular polymeric substances in anaerobic digested sludge

The composition and effects of solution conditions on the physicochemical properties of the stratification components of extracellular polymeric substances （EPS） in anaerobic digested sludge were determined. The total EPS in anaerobic digested sludge were extracted by the cation exchange resin method. Another EPS extraction method, the ceutrifugation and sonication technique was employed to stratify the EPS into three fractions： slime, loosely bound （LB）-EPS, and tightly bound （TB）-EPS from the outside to the inside of the anaerobic digested sludge. Proteins and polysaccharides were dispersed uniformly across the different EPS fractions, and humic-like substances were mainly partitioned in the slime, with TB-EPS second. Protein was the major constituent of the LB-EPS and TB-EPS, and the corresponding ratios ranged from 54.0% to 65.6%. The hydrophobic part in the EPS chemical components was primarily comprised of protein and DNA, while the hydrophilic part was mainly composed of polysaccharide. In the slime, the hydrophobic values of several EPS chemical components （protein, polysaccharide, humic-like substances and DNA） were all below 50%. The protein/polysaccharide ratio had a significant influence on the Zeta potentials and isoelectric point values of the EPS： the greater the protein/polysaccharide ratio of the EPS was, the greater the Zeta potential and the higher the isoelectric point value were. All Zeta potentials of the EPS showed a decreasing trend with increasing pH. The corresponding isoelectric point values （pH） were 2.8 for total EPS, 2.2 for slime, 2.7 for LB-EPS, and 2.6 for TB-EPS. As the ionic strength increased, the Zeta potentials sharply increased and then gradually became constant without charge reversal. In addition, as the temperature increased （〈 40℃）, the apparent viscosity of the EPS decreased monotonically and then gradually became stable between 40 and 60℃.

高含固率污泥厌氧消化系统的启动方案与试验

高含固污泥厌氧消化技术是目前国内外的研究热点。该文以上海市白龙港污水处理厂脱水污泥稀释而成的含固率为10％的污泥作为研究对象，对高含固污泥厌氧消化技术进行了初步的探讨。试验结果表明，厌氧消化系统的进泥含固率升高至10％后，每投入1m3的污泥产气约16～18m3沼气，远高于现有浓缩污泥厌氧消化系统的产气率（8～10m3沼气／m3污泥）。高含固率污泥厌氧消化系统推荐采用清水启动策略，即消化罐内介质的初始状态为清水（二沉池出水），之后以不同投配率投加原污泥，避免系统启动过程中的VFA的积累，尤其是丙酸含量的积累。该研究成果不仅可为该污水处理厂现有污泥厌氧消化系统未来的扩建改造服务，而且可为国内同类工程提供借鉴和示范。

微生物制剂在污水处理中的应用研究

本文采用由氨氧化细菌和硝化细菌组成的微生物制剂投加到污泥厌氧消化液中,可降解较高浓度的氨氮,亚硝酸盐和硝酸盐的积累受污泥厌氧消化液pH的影响,pH低于6时硝化活性基本受抑制,pH在8~9之间可实现短程硝化。

磷酸盐缓冲液初始pH值对高含固污泥厌氧消化性能影响

在高含固污泥厌氧反应器中投加浓度为20 mmol·L-1(以P元素计)的磷酸盐缓冲溶液,考察不同pH值的缓冲溶液对污泥厌氧消化效果的影响。结果表明,投加pH为7.0的缓冲溶液后,总甲烷产量达到最大值61.08 L,较对照提高了38.1%,而投加pH为7.5和8.0的缓冲溶液后对产甲烷过程产生了抑制。投加缓冲溶液的各组厌氧消化至45 d,污泥的VS去除率均高于对照组。动力学研究表明,蛋白质和多糖的降解符合一级反应动力学,投加缓冲溶液有利于加速蛋白质的降解,而对多糖的降解无明显影响。