重金属元素在污泥-蚯蚓-蚯蚓粪中的迁移转化研究

发布时间：2018-01-02 20:36

本文关键词：重金属元素在污泥-蚯蚓-蚯蚓粪中的迁移转化研究　出处：《成都理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,伴随着我国城市规模的快速扩张,城市污水处理厂的污水处理容量大幅增长,生活污水在城市污水处理厂得到了净化,而其中的各自污染物大部分遗留在污泥中,污泥成了污水中各种污染物的“收容所”。作为污水处理的副产品——污泥,正在成为新的环境隐患。科学处理和合理利用污泥是目前城市污水处理的最后一环,也是亟待解决的关键问题。论文依托四川省环境科学研究院承担的《四川省城市生活污水处理厂污泥特性及实用处置技术研究》课题,探索和研究城市生活污泥处理处置工艺技术中利用污泥养殖蚯蚓过程中重金属元素迁移转化规律。利用污泥养殖蚯蚓,此过程不但能饲养出有经济价值的蚯蚓成品,而且蚯蚓具有很强的消化能力,它在酶类和好氧微生物的协同代谢作用下,通过砂囊、消化道对污泥进行分解、转化,消耗污泥中的有机质,排出酸碱中性、水气调和、孔隙率高的具团粒结构的蚯蚓粪,使污泥脱水化、稳定化、除臭化、无害化、资源化。在这个转化过程中,重金属元素在污泥处理前后不同样品中的变化规律对于该项技术的实际应用有重要评价作用。论文在前人研究的基础上,通过实地采样、和实验分析,查明了成都市周边八处生活污水处理厂的污泥样品中重金属元素的特征,对比研究了两处实验区所用污泥样品处理前后的重金属元素变化规律,探讨了蚯蚓在不同生理阶段体内重金属元素含量以及吸收富集规律,并进行了质量评价。通过研究,取得以下成果和认识:1、污泥样品的pH值介于5.62至6.71,有机质平均含量为46%,污泥样品中重金属元素的变异系数大小关系为:ZnCuCrPbNiCdAsHg。各污水处理厂的污泥重金属含量变化较大,与城市规划布局差异和环境背景有关,龙泉驿区的多家电镀企业和双流的皮革染料企业,可能是导致Zn、Cr等重金属元素含量在辖区污水处理厂产生的污泥中偏高的原因。2、参照《城镇污水处理厂污泥处置农用污泥》(CJ/T309-2009)标准,W01(双流1)、W02(双流2)、W04(成都市)、W05(郫县)、W07(德阳)六个样品的污泥可以满足B级农用污泥标准,W03(温江)、W06(金堂)和Ws(双流实验区)样品的污泥重金属含量满足表可以满足A级污泥标准进行农用,Wj(温江实验区)污泥样品重金属含量不满足农用污泥的标准,只能作为园林绿化使用;W08(龙泉驿)污泥Zn含量过高,不能进行土地利用。处理后的蚯蚓粪Fj、Fs的pH值上升,有机质含量下降,重金属元素含量明显降低,两处样品中重金属元素含量都满足农用A级污泥标准,且重金属含量大幅低于标准中的限值。3、污泥样品中重金属元素Hg、Pb、As、Cr的化学形态分布以残渣态为主,生物可利用性差。而Zn、Ni、Cd元素的化学形态中水溶态、碳酸盐结合态、腐殖酸结合态占比较高,生物可利用性较好。在利用蚯蚓处理后,Cd、Pb、Cu的生物可利用性有所增强,As、Hg、Cr、Zn的变化不明显,其中As、Hg、Cr的仍然以残渣态为主,生物可利用性低。4、污泥和蚯蚓粪中各重金属元素的潜在生态风险危害程度从大到小依次为:CdCuHgAsZnPbNiCr。处理前的污泥潜在生态风险危害为很强或中等。处理后蚯蚓粪的潜在生态风险危害降为轻微。对潜在生态危害指数(RI)的值贡献较大的是Cd、Hg。结合重金属元素含量及化学形态特征,污泥和蚯蚓粪中的Cd因其含量高、生物可利用性强、潜在生态危险性大,是最应重视的重金属元素。5、利用蚯蚓处置污泥过程中,相比蚯蚓粪中重金属的含量,蚯蚓对Cd、Pb表现出了生物富集作用,蚯蚓对污泥中各种重金属元素吸收能力从强到弱依次为:CdPbAsHgCuZnNiCr。在蚯蚓的成长过程中(幼蚓-若蚓-成蚓)重金属元素含量总体逐渐升高。若蚓-成蚓期的蚯蚓对Zn吸收速率相比幼蚓-若蚓期增高,而对Pb和Cr的吸收速率略有降低。
[Abstract]:In recent years, with the rapid expansion of city scale, city sewage treatment plant sewage treatment capacity increased significantly, the sewage in the city sewage treatment plant was purified, and most of them left in the respective pollutants in sludge, sewage sludge into various pollutants in the shelter. As for sewage treatment a by-product of sludge, is becoming a new environmental problems. Scientific and reasonable utilization of sludge treatment is currently the city sewage treatment at the end of a ring, it is also a key problem to be solved. Based on the assumed Environmental Science Research Institute of Sichuan province "in Sichuan province city life sludge characteristics and practical disposal technology of the sewage treatment project", explore study on city life and heavy metal sludge sludge treatment and disposal technology in breeding by earthworms in the process of migration. The use of sludge earthworm, this The process can not only raise the economic value of earthworms and earthworm products, has a strong ability to digest it in cooperative metabolism enzymes and aerobic microorganisms, through the digestive tract of gizzard, decomposition, transformation of sludge, consumption of organic matter in the sludge discharge, acid and alkali, water and granular structure, porosity the vermicompost, the sludge dewatering and deodorization, stabilization, harmless, resource. In the process, the variation in heavy metal elements in different samples of sludge before and after treatment for practical applications of this technology have an important role in the evaluation. On the basis of previous studies, through field sampling, and experimental analysis, the characteristics of heavy metal around the city of Chengdu eight sewage treatment plant sludge samples and identify the comparative study of the two experimentation area with heavy metal sludge samples before and after treatment Changes of earthworms in the content of heavy metals in different physiological stages and the law of absorption and accumulation, and the quality evaluation. Through the research, conclusions are as follows: 1. The pH value of sludge samples ranged from 5.62 to 6.71, the average content of organic matter was 46%, heavy metals in sludge samples of the coefficient of variation relationship ZnCuCrPbNiCdAsHg.: the sewage treatment plant sludge heavy metal content varied greatly, and city planning layout difference and background, a number of electroplating enterprises in Longquanyi district and Shuangliu leather dye enterprises, may lead to Zn,.2 Cr and other reasons for the high content of heavy metal elements in the area of sewage treatment plant sludge, reference < factory sludge disposal sludge of urban sewage treatment (> CJ/T309-2009) standard, W01 (double 1), W02 (double 2), W04 (Chengdu), W05 (Pixian), W07 (Deyang) six samples of sludge In order to meet the B standard of agricultural sludge, W03 (Wenjiang), W06 (Jintang) and Ws (double experimentation area) content of heavy metals in sludge samples meet the table can meet the standard of class a sludge farm, Wj (Wenjiang experimentation area) of heavy metals in sludge samples do not meet the standard of agricultural sludge, only as landscaping; W08 (Longquanyi) sludge Zn content is too high, not for land use. The vermicompost after Fj treatment, Fs pH value, organic matter content decreased, the content of heavy metals decreased significantly, the content of heavy metals in the two samples all meet the standard of agricultural grade sludge, and the heavy metal content is significantly lower than in the standard limit of.3, heavy metal sludge the samples of Hg, Pb, As, Cr in the chemical speciation of residual iiifraction bioavailability. Zn, Ni, Cd elements of the chemical form of water soluble, carbonate bound, humic acid bound accounted for a higher bioavailability The better. In the use of earthworms, Cd, Pb, Cu bioavailability increased, As, Hg, Cr, Zn did not change significantly, including As, Hg, Cr are mainly in residual fraction. The low bioavailability of.4, the potential ecological risk of heavy metals harm degree sludge and vermicompost from large to small is as follows: the potential ecological risk of sludge harm before CdCuHgAsZnPbNiCr. treatment for high or medium. After the treatment of the potential ecological risk of vermicompost hazard is reduced slightly. The potential ecological risk index (RI) value of the contribution is Cd, Hg. combined with the contents of heavy metals and chemical morphological characteristics of sludge and vermicompost in Cd because of its high content of bioavailability and potential ecological risk of heavy metals, is the most should pay attention to the.5, sludge disposal by using earthworm, compared the content of heavy metal in vermicompost, earthworm on Cd, Pb showed biological Enrichment of heavy metals in sludge earthworm absorption capacity were from strong to weak CdPbAsHgCuZnNiCr. in the growth process of earthworm (juvenile - earthworm - if the earthworm into) the contents of heavy metals increased gradually. If the overall - Yinqi earthworm on Zn absorption rate compared to juvenile - if the earthworm period increased, and the absorption rate of Pb and Cr decreased slightly.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703;X174

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