城市污水处理厂剩余污泥的物化性质及其对脱水性的影响研究
文献类型：学位论文
| 作者 | 刘园园 |
| 学位类别 | 硕士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 王东升 |
| 关键词 | 城市污水处理厂 污泥物化性质 脱水性 污泥调理 有机物组成 wastewater treatment plant physicochemical characteristics of sludge dewaterability sludge conditioning organic composition |
| 其他题名 | Physico-chemical characteristics of full scale sewage sludges in relation to dewaterability |
| 学位专业 | 环境工程 |
| 中文摘要 | 本课题对北京市四个污水处理厂的剩余污泥进行了历时8个月的调查研究，污水厂的处理工艺分别为厌氧-缺氧-好氧脱氮除磷工艺（A2O）、膜生物反应器（MBR）、氧化沟和传统活性污泥法。采用超声-离心法将污泥分为溶解性胞外聚合物（slime）、疏松型胞外聚合物（LB-EPS）、紧密型胞外聚合物（TB-EPS）和细胞相（pellet）四层，结合三维荧光（EEM）技术深入研究污泥胞外聚合物（EPS）组成。通过长期监测污泥的物理化学性质，观察了污泥特性动态变化特征，剖析了污水处理工艺与污泥特性之间的联系，探索了污泥物化性质之间的相互关系，并且研究了物化性质对脱水性的影响。此外，本课题还研究了阳离子型聚丙烯酰胺（PAM）、聚合氯化铝（PAC）和氯化铁的调理过程，分析了几种混凝剂调理机制的异同，以期对污泥调理技术提供理论支撑。 污泥样品的荧光光谱图中都存在225/330 nm和275/330 nm两个峰，分别代表芳香类蛋白质和微生物代谢产物（SMP）；由荧光区域整合（FRI）结果可知，污泥主要由SMP、蛋白类物质组成，类腐殖质物质所占比例也比较高。污泥性质在夏季发生显著变化：脱水性达到最佳，6月各污水厂污泥的毛细吸水时间（CST）最低，均值为1.929 s∙L/g；EPS浓度降至最低，可能是环境压力和微生物种群变化共同作用的结果；蛋白类物质含量减少，减少的幅度大于SMP等物质。从5月至12月，污泥的VSS/TSS、pH都呈现下降的趋势，污泥中多糖、蛋白质、腐殖酸的含量以及各荧光物质所占比例都有变化，但变化规律比较复杂。 本研究中，污水处理工艺对污泥特性影响不大，只有粒径和VSS/TSS与处理工艺有一些联系。污泥粒径分布受到pH的影响，酸性条件下污泥粒径较大；VSS/TSS与pH呈负相关(R= -0.41, p<0.05)，可能与微生物代谢活动有关。蛋白质与多糖的含量呈负相关，与腐殖酸含量呈正相关，多糖与腐殖酸的含量的关系不显著，蛋白质与多糖的负相关可能与裂解酶有关。分析FRI结果发现，SMP与其它有机组分都有很好的正相关性。此外，DOC与粒径、zeta电位等表观性质有较好的相关性，表明有机组成会影响污泥表观性质。 污泥脱水过程中，微小颗粒可能起到了重要的作用。脱水性（以CST衡量）与d0.1 (R=0.48, p<0.05)及d0.5 (R=0.40, p<0.05)都有较好的相关性，但与d0.9的相关性较差。此外，CST与slime层DOC的相关性较好(R= 0.583, p<0.01)，与pellet层DOC有一定相关性(R= 0.449, p<0.05)，与L、T层DOC的相关性不显著。与CST相关性较好的还包括slime层蛋白质含量（R=0.719, p<0.01），LB-EPS层多糖含量(R= 0.464, p<0.01)，slime层DOC (R= 0.583，p<0.01)。脱水性是有机负荷率、污水有机物组成、剪切力水平等多种复杂条件共同作用的结果，所以脱水性与单一的物化指标（如污泥粒径、EPS等）之间很难找到显著的相关性。 PAC和氯化铁的投加量远高于PAM，而且二者的调理效果比PAM差。PAM调理形成的污泥粒径非常大，最高达到845.561 μm，是污泥原始粒径的8.6倍，远大于PAC或氯化铁调理后的污泥粒径。当使用PAM和PAC调理时，各层有机物含量变化不大，氯化铁调理可有效减少污泥slime层有机物。PAM分子量相同时，阳离子度越高，调理效果越好。投加混凝剂后slime、LB-EPS 和TB-EPS 中有机物含量都降低，有效提高了污泥的脱水性能。 |
| 英文摘要 | In this paper, an investigation of excess sludge from four wastewater treatment plants(WWTPs) in Beijing has been proceed for 8 months. The treatment process of these four WWTPs is anaeroxic-anoxic-oxic(A2O), membrane bio-reactor(MBR), oxidation ditch, and traditional activated sludge process, respectively. Excess sludge is divided into slime, loosely bounded extracellular polymeric substances(LB-EPS), tightly bounded extracellular polymeric substances(TB-EPS) and pellet, using an ultrasonic-centrifugation method. Three-dimensional fluorescence excitation emission spectrum technology(EEM) has been used to study the composition of extracellular polymers(EPS). Through the long-term monitoring of physicochemical properties of sludge, dynamic characteristics of sludge properties, the link between physicochemical properties, and their impact on the dewaterability have been studied. Besides, sludge conditioning process using cationic polyacrylamide(PAM), poly aluminium chloride(PAC) and ferric chloride has also been studied, by analyzing the differences of conditioning mechanism between these coagulants, aiming at providing theoretical support for sludge conditioning. Two peaks are shown in the fluorescence spectra of sludge samples, which are located in 225/330 nm and 275/330 nm, representing aromatic protein and solube microbial products(SMP) respectively. According to the fluorescent regional integration(FRI), sludge is mainly composed of SMP, protein-like and humic acid-like organics. Physicochemical characteristics of sludge changes significantly in summer. Dewaterability achieves the best state as the average value of capillary suction time(CST) is 1.929 s∙L/g. Meanwhile, concentration of EPS and protein-like organics decreased significantly. From May to December, VSS/TSS and pH have declied a little. Meanwhile, the content of polysaccharide, protein, humic acid and the proportion of fluorescent matter changes irregularly. In this study, wastewater treatment processes have little effects on sludge characteristics because only particle size and VSS/TSS are connected with treatment processes. Particle size is bigger under acidic condition, indicating that sludge particle size distribution is affected by pH. VSS/TSS is negatively correlated with pH(R= -0.41, p<0.05), probably due to microbial metabolic activity. Protein is negatively correlated with polysaccharide and positively correlated with humic acid, while no significant relationship is observed between humic acid and polysaccharides. Negative correlation of protein and polysaccharide may due to lyase. FRI results shows that SMP and other organic components have good positive correlations. Besides, DOC shows good correlation with physical properties such as particle size and zeta potential. so organic composition may affect the sludge apparent properties. Small particles may play an important role in the process of sludge dewatering. Dewaterability, which is measured by CST, shows good correlations with d0.1(R=0.48, p<0.05) and d0.5(R=0.40, p<0.05), but poor correlation with d0.9. Besides, CST has good correlations with DOC of slime(R= 0.583, p<0.01) and pellet(R= 0.449, p<0.05), but poor correlations with DOC of LB-EPS and TB-EPS. Those properties which can effect CST include protein content in slime(R=0.719, p<0.01), polysaccharide content in LB-EPS(R= 0.464, p<0.01) and DOC content of slime(R= 0.583, p<0.01). Dewaterability is the result of organic loading rate, organic matter in wastewater, shear stress level and other complicated condition, hence it’s hard to find a significant correlation between dewaterability and a single physicochemical indicator. Comparing to PAM, PAC and ferric chloride require larger doses and show poorer conditioning effect. The sludge flocs become very large after adding PAM. d0.5 can get 845.561 μm,which is 8.6 times of the original size and is much larger than the sludge flocs formed after adding PAC or ferric chloride. When conditioning by PAM or PAC, organic matter content of each layer changed a little, while ferric chloride can effectively reduce organic matter in slime. PAM with higher degree of cation has better conditioning effect, when molecular weight is at the same time. The improvement of dewaterability after conditioning may due to damage of EPS, as decrease of organics in slime, LB-EPS and TB-EPS has been observed. |
| 公开日期 | 2015-07-08 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/15611]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 刘园园. 城市污水处理厂剩余污泥的物化性质及其对脱水性的影响研究[D]. 北京. 中国科学院研究生院. 2014. |
入库方式： OAI收割
来源：生态环境研究中心
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