【作者】 田锁霞；

【导师】 孙振钧； 胡林；

【作者基本信息】 中国农业大学 ， 环境工程， 2014， 博士

【摘要】 厌氧发酵液具有悬浮固体含量高、有机负荷高、可生化性差、处理难度大的特点,单一的处理技术处理效果差,复合处理的方法越来越受到重视。本研究把蚯蚓引入湿地系统,构建蚯蚓生态湿地系统,利用蚯蚓的物质消化与分解特性,通过蚯蚓的活动,提高人工湿地处理厌氧发酵液的效果。本研究的主要内容包括：探索蚯蚓对氨氮的耐受性及在模拟湿地环境下的适应机理；研究蚯蚓生态湿地系统中蚯蚓活动对污染物去除和转化的影响及缓解堵塞的效果；研究蚯蚓生态湿地系统与其他处理方式联合处理厌氧发酵液的效果与参数优化,确定蚯蚓在同步处理污水污泥的潜力和可行性,为处理厌氧发酵液等难处理废液提供一种新的途径。主要研究结果如下：(1)氨氮是污水中常见的污染物控制指标,本研究采用滤纸接触法(OECD标准)测试了氨氮在48h暴露期内对蚯蚓的存活影响,在模拟湿地环境中研究了蚯蚓耐氨氮胁迫的生化机理,结果表明氨氮对蚯蚓的半致死浓度LC50=343.1mg/L,属于低毒。蚯蚓在耐受氨氮负荷及适应湿地环境的过程中,蚯蚓体内过氧化氢酶(CAT)、谷胱甘肽硫转移酶(GST)、总抗氧化能力(T-AOC)的活性被显著激活,蚯蚓体内抗氧化体系维持了机体自由基的动态平衡,发挥了抵御氨氮胁迫的功能。(2)通过在无机滤料体系,有机-无机滤料体系研究蚯蚓对厌氧发酵液的适应性,确定了滤料的组成,获得了驯化蚯蚓适应厌氧发酵液的参数。在水力负荷10cm/d、间歇进水的条件下,以氨氮为控制指标,建议在初期将厌氧发酵液进水稀释使氨氮控制在120-150mg/L内驯化蚯蚓后再进一步提高进水有机负荷。(3)采用模拟废水研究了蚯蚓在蚯蚓生态湿地系统中的分布与活动规律,蚯蚓对污染物去除和转化的影响及缓解堵塞的效果,结果显示蚯蚓主要分布在垂直流湿地的0-10cm层,蚯蚓活动能提高系统氧含量,缓解湿地堵塞情况。提高了系统对氨氮的硝化作用,但是使系统缺乏反硝化环境而不利于总氮的去除。(4)采用蚯蚓生态湿地-水平潜流湿地混流系统处理厌氧发酵液,在进水平均有机负荷达到1.82kg/m2·d,水力负荷10、20cm/d的条件下,对COD、TP、SS的去除率达到了90%以上,氨氮去除率达80%以上,总氮去除率也维持在60%以上。提高水力负荷对污染物的消减量更有优势,水平潜流湿地对总氮的消减优于蚯蚓生态湿地。两种水力负荷下,混流湿地出水COD、氨氮、总磷、SS均能达到《畜禽养殖业污染物排放标准》要求。蚯蚓使混流系统对COD、氨氮的去除分别提高了2%、17%,同时具有同步处理污水污泥,缓解湿地堵塞的效果。(5)氧化塘-蚯蚓生态湿地复合系统处理厌氧发酵液的参数研究：在进水有机负荷达到2.5kg/m2·d,水力负荷100cm/d的条件下,复合系统处理出水水质稳定,蚯蚓生态湿地系统中硝化作用显著,处理出水COD、氨氮、总磷含量能达到《畜禽养殖业污染物排放标准》要求,结果进一步优化了蚯蚓生态湿地的进水负荷及应用范围。(6)综合分析了蚯蚓生态湿地处理厌氧发酵液的应用潜力及限制性,对工程应用提出相应的优化措施。更多还原

【Abstract】 Anaerobic digestion slurry is a kind of wastewater whose characteristical is high solid content, high organic loading and hard for biodegradation.In this paper, Earthworm-constructed wetland was designed based on the ecological functions of earthworms, the aim of this research was to investigate the potential of integrating earthworms into the constructed wetlands, in order to realize whether they could mitigate clogging problems as well as to improve the treatment performances. Research of this paper was divided into the following three parts:Study on earthworms’ tolerance and adaptation mechanism of ammonium under simulated wetland environment; Earthworm-constructed wetland was applied to treat synthetic sewage, the purpose of the study was to clarify the role of earthworms in the removal and transformation of pollutants, its impacts on mitigation clogging was also investigated. Earthworm-constructed wetland was applied to treat anaerobic digestion slurry combined with other treatment, in order to make sure whether earthworms could mitigate clogging problems as well as to improve the treatment performances. So that this study would provide a new approach to treat anaerobic digestion slurry. The main research results are summarized as follows:(1) Ammonium is a common pollutant in sewage,this study used the filter paper contact method (OECD Standard Methods)to test the survival of earthworms in48h exposure period,and also studied the adaptation mechanism in earthworms of resistance to ammonium stress in simulated wetland environment, the results showed that a relatively low toxicity of ammonium with ammonium chloride having an LC50=343.1mg/L. Ammonium activated catalase (CAT), glutathione S-transferase (GST), total antioxidant capacity (T-AOC) activity in earthworms, the antioxidant system maintained the homeostasis of free radicals in earthworm body, playing an important role in resisting ammonium stress.(2) The adaptability of earthworms subjected anaerobic digestion slurry in inert and inert-orgnic filler were studied, and the treatment efficiency was also assessed. So the composition of the media was determined, and gained the parameters getting earthworms acclimated to anaerobic digestion slurry. In the conditions of10cm/d hydraulic loading and intermittent feeding mode, it was recommended that anaerobic digestion slurry should be diluted,so that ammonium was controlled at120-150mg/L, then increased the organic loads after earthworms acclimating the anaerobic digestion slurry.(3) Earthworm-constructed wetland was applied to treat synthetic sewage to study the effect of the movement and feeding behavior of earthworms on pollutant removal and mitigation clogging. Results showed that:earthworms mainly live in vertical flow wetland0-10cm layer, Earthworms could mitigate clogging of wetland and increase the oxygen content in the effluent. Earthworms contributed to improve the nitrification of ammonia. However, they made the wetland lack denitrification environment to remove total nitrogen.(4) The earthworm-constructed wetland followed by horizontal ones were determined to process anaerobic digestion slurry. When the average influent organic load reached1.82kg/m2.d, hydraulic loading werel0,20cm/d, COD, TP, SS removal efficiency reached90%, ammonium removal rate reached more than80%, and the total nitrogen removal efficiency is also maintained above60%. Improving the hydraulic load reduced greater amount of pollutants, the performance of horizontal subsurface flow wetlands in mitigatiing TN and TP is better than earthworm-constructed wetland. Adding earthworms increased removal of COD, NH4-N by2%,17%respectively. Earthworms had the effect of synchronous treatment of sewage sludge and slurry to mitigating clogging.(5) The integrated system of oxidation pond and earthworm-constructed wetland to treat anaerobic digestion slurry was undertaken, when the influent COD loading reached2.5kg/m2.d, the hydraulic loading was100cm/d, The removal performance of the integrated system was stable. Nitrification in earthworm-constructed wetland was significantly strong, COD, ammonium, and TP in the effluent met the standard for swine wastewater effluent. The results further optimized the hydraulic load and applications of the earthworm-constructed wetland.(6) Comprehensive analysis was made about the potential appliying earthworm-constructed wetland to treat anaerobic digestion slurry and its restriction, the solutions corresponding engineering applications were proposed at the same time.更多还原