Analysis of bacterial community structures in two sewage treatment plants with different sludge properties and treatment performance by nested PCR-DGGE method

The bacterial community structures in two sewage treatment plants with different processes and performance were investigated by denaturing gradient gel electrophoresis （DGGE） of nested polymerase chain reaction （nested PCR） amplified 16S rRNA gene fragments with group-specific primers. Samples of raw sewage and treated effluents were amplified using the whole-cell PCR method, and the activated sludge samples were amplified using the extracted genomic DNA before the PCR products were loaded on the same DGGE gel for bacterial community analysis. Ammonia-oxidizing bacterial and actinomycetic community analysis were also carried out to investigate the relationship between specific population structures and system or sludge performance. The two plants demonstrated a similarity in bacterial community structures of raw sewage and activated sludge, but they had different effluent populations. Many dominant bacterial populations of raw sewage did not appear in the activated sludge samples, suggesting that the dominant bacterial populations in raw sewage might not play an important role during wastewater treatment. Although the two plants had different sludge properties in terms of settleability and foam forming ability, they demonstrated similar actinomycetic community structures. For activated sludge with bad settling performance, the treated water presented a similar DGGE pattern with that of activated sludge, indicating the nonselective washout of bacteria from the system. The plant with better ammonium removal efficiency showed higher ammonia-oxidizing bacteria species richness. Analysis of sequencing results showed that the major populations in raw sewage were uncultured bacterium, while in activated sludge the predominant populations were beta proteobacteria.     

Municipal sludge as landfill barrier material

The aim of this research is to find substitute barrier materials for natural clay from two kinds of municipal sludge: waterworks sludge( Sw ) and dredging sludge( Sd ). Laboratory tests were performed firstly to determine their Atterberg limits and hydraulic conductivity.Based on the results, the use of waterworks sludge was recommended. Then, shear strength tests were performed and it was found the shear resistance property of waterworks sludge is strong enough to maintain slope stability. In order to evaluate the possibility of secondary pollution, the heavy metal contents of waterworks sludge was determined and the results indicated that secondary pollution is unlikely happened. Finally, economic analysis proves that reusing waterworks sludge as barrier will reduce the lost a great for both landfill and waterworks. Based on the results, waterworks sludge was proposed to use and a further long-term simulated landfill test was suggested.     

五里湖淤泥现状及生态清淤

对五里湖淤泥现状进行了调查，表明影响五里湖水质的主要污染是五里湖湖底的淤泥，目前淤泥平均厚度为0.6m-0.8m，淤泥量约360万t。根据淤泥中有机质，TN和TP水平分布，有机质平均为40.37g/kg，TP平均值为2.61g/kg，TN平均值为1.19g/kg，均超过了太湖和梅梁湖底泥中有机质，TN和TP的平均值，五里湖底泥的有机污染已相当严重。指出淤泥是湖体营养盐和污染物的聚集地和储存仓库，不断向水体释放营养物质和污染物质，淤泥所产生的二次污染已成为五里湖湖水富营养化和藻类爆发的主要原因之一。提出为改善五里湖水质，应采用生态清淤治理五里湖淤泥污染，同时将生态清淤与交通，绿化和生态农业建设有机结合起来，合理利用清出的淤泥，提高生态清淤的综合效益。     

Cultivation of aerobic granules for simultaneous nitrification and denitrification by seeding different inoculated sludge

Cultivation of aerobic granules for simultaneous nitrification and denitrification in two sequencing batch airlift bioreactors was studied. Conventional activated floc and anaerobic granules served as main two inoculated sludge in the systems. Morphological variations of sludge in the reactors were observed. It was found that the cultivation of aerobic granules was closely associated with the kind of inoculated sludge. Round and regular aerobic granules were prevailed in both reactors, and the physical charactedstics of the aerobic granules in terms of settling ability, specitic gravity, and ratio Of water containing were distinct wnen the inoculate sludge differe. Aerobic granules formed by seeding activated floc are more excellent in simultaneous nitrification and denitrification than that by aerobic granules formed from anaerobic granules. It was concluded that inoculated sludge plays a crucial role in the cultivation of aerobic granules for simultaneous nitrification and denitrification.     

Changes of Cu, Zn, and Ni chemical speciation in sewage sludge co-composted with sodium sulfide and lime

A batch composting study was performed to evaluate the feasibility of co-composting sewage sludge with sodium sulfide and lime （SSL） mixture （Na2S/CaO= 1：1）, aiming at reducing the availability of heavy metals in the sludge compost. Sewage sludge with sawdust as a bulking agent was amended with SSL at 3% （w/w, dw）, and composted for 15 d in laboratory batch reactors. The four stages of the Tessier sequential extraction method was employed to investigate changes in heavy metal fractions of Cu, Zn, and Ni in sewage sludge composted with SSL. For all the three metals, the mobile fractions, such as, exchangeable and carbonate bound were mainly transformed into low availability fractions （organic matter and sulfide, Fe-Mn oxides bound and residual forms）, and the addition of SSL enhanced this transformation. Therefore, SSL is a suitable material to co-compost with sewage sludge to reduce the availability of heavy metals. According to the cabbage seed germination test, a SSL amendment of ≤3% （w/w, dw） is recommended to co-compost with sewage sludge.     

絮凝浓缩武汉市巡司河底淤泥的研究

目的研究武汉市巡司河底淤泥在不同无机絮凝剂及PAM的助凝作用下淤泥清浑分界面的沉降速率、淤泥浓缩比以及淤泥沉降指数的变化情况。方法采用实验研究的方法,对巡司河底淤泥进行沉降实验,并通过沉降分析找到最佳脱水效果的脱水剂。结果当淤泥质量分数为10%时,Ca(OH)2取得的絮凝脱水效果最好,Ca(OH)2投加比为5 g/L,PAM投加比为0.04 g/L时,淤泥清浑分界面的沉降速率最大可达到3.7 cm/min,淤泥浓缩比为3.94,淤泥沉降指数为24.9%。结论 Ca(OH)2和PAM对巡司河底淤泥的脱水有促进效果,淤泥在Ca(OH)2和PAM共同作用下先后经历了自由沉降、絮凝沉降、区域沉淀和压缩沉降。     

日本利用海绵体活性淤泥处理技术

日本京都水研株式会社利用海绵体活性淤泥进行废水处理时,高浓度淤泥能有效附着在特殊固定床 (生物试管道 )的空隙中而不致于脱落。这种方法使历来的活性淤泥处理法中不为人所发现的多种特殊性能得以发挥,实现了低成本化并节省空间。 　　1.提高单位容积负荷,压缩装置结构 　　保持在高浓度的活性淤泥作为大型颗粒化了的活性淤泥 (即所谓的海绵体活性淤泥 )来利用,它便能发挥前所未有的多种功能。这被称作集团功能,而其海绵体则具有不发生膨胀的优点。另外,将标准活性淤泥法与之比较可知,该技术中只需要通常接触滞留时间约 1/4,便可…     

淤泥开发 化腐朽为神奇

近年来,越来越多的国家发出向淤泥要能源的口号。不少国家已开始利用厌氧细菌将下水道淤泥“消化”,然后收集其中产生的沼气作为燃料,并将下水道污泥制成固体燃料。 一举多得的淤泥开发 对下水道污泥作为固体燃料的开发与实用化研究,欧洲国家目前居领先地位。德国汉堡贝伦化学公司从2002年开始,将工厂下水道排放的废水(其中含10％的普通生活污水)进行处理,所得活性污泥作为燃料。他们在下水道污水中加入有机凝集剂,再用电力脱水机脱去部分水分,加入一定比例的粉煤,最后利用压滤机榨干水分,用这种方法制成的燃料发热量大约是9200～10000千焦/千克,并且将其干燥、粉碎后不影响燃烧性能。 从下水道淤泥中挖掘潜在能源,不仅开辟了能源新途径,还可以从根本上解决城市下水道淤泥污染问题。对改善城市地下水水质有着至关重要的作用。 湖泊、河道和城市下水道淤泥的处理是许多国家共同面临的环境管理问题。通常的做法是,将清理出的淤泥直接送至农村作为肥料使用。由于淤泥未经净化除毒处理,这样不仅影响环境,造成二次污染,而且淤泥使用价值也不能充分发挥。     

高含水率疏浚淤泥混合固化轻质土试验研究

疏浚淤泥EPS颗粒混合轻质土是一种新型的轻质土工材料,具有密度小、强度高等特点,在工程中具有广泛的应用前景。本文对高含水率的白马湖疏浚淤泥进行了室内轻质土配比试验,系统分析了水泥掺量、EPS颗粒掺量以及养护龄期等因素对轻质土的密度及无侧限抗压强度这两个重要参数的影响规律。研究结果表明,轻质土的密度主要由EPS颗粒掺量控制,而水泥掺量和养护龄期对轻质土的密度影响较小;轻质土的强度受水泥掺量、EPS颗粒掺量和养护龄期的影响,其强度随龄期与水泥掺量的变化规律与一般水泥土一致,而强度与EPS颗粒掺量之间存在一个阈值。     

太湖淤泥烧结砖的制备及其性能

以太湖淤泥和粉煤灰为原料,干燥后混合加湿搅拌,压制成40 mm×40 mm×40 mm的试样,经干燥后放入电阻炉中焙烧,测试分析了不同粉煤灰掺量和焙烧温度下淤泥烧结砖的吸水率、抗压强度、腐蚀性及重金属浸出等性能。结果表明:增加粉煤灰掺量,砖体吸水率增大,抗压强度降低;当粉煤灰掺量30%、烧结温度950℃时,淤泥烧结砖强度可达到13.6 MPa,满足国家承重墙(MU10)使用标准。砖体浸出液微偏碱性,但不具有腐蚀性,高温焙烧可使淤泥中重金属得到有效固化。