【作者】 陈蕾；

【导师】 刘和； 陈宇；

【作者基本信息】 江南大学 ， 环境工程（专业学位）， 2021， 硕士

【摘要】 目前环境领域关心的新兴污染问题,特别是疏水性的新兴污染物,由于其较高的生物毒性且易在污水处理厂的污泥中富集,导致难以被传统污水处理工艺去除。厌氧消化是实现污泥稳定化、无害化和减量化的技术,同时可以通过沼气等形式回收资源,因此在国内外被广泛应用。研究污泥厌氧消化过程中疏水性新兴污染物（选取典型抗菌剂三氯生（Triclosan,TCS）为代表）在固相和液相中的迁移规律对于该类污染物的去除意义重大。本文探究了TCS对污泥厌氧消化性能的影响并通过研究污泥溶液中关键因素、污泥性质和污泥吸附位点对TCS吸附的影响,借助主成分分析法（Principal component analysis,PCA）找寻TCS在消化过程中迁移的规律。主要研究结论如下:（1）考察了有机质浓度、pH、氨氮（NH₄⁺-N）浓度和温度这几种溶液中关键因素对TCS固液分配的影响。结果表明溶液中的蛋白质通过疏水作用、氢键作用与TCS结合促使液相中TCS的富集,使固液分配系数（K_d）由12645.92 L/kg显著降低至56.02L/kg。多糖浓度升高使K_d由16026.44 L/kg降低至8444.06 L/kg。腐殖酸（Humic acid,HA）浓度升高使K_d由9034.31 L/kg降低至7244.75 L/kg。多糖和HA主要通过氢键作用力与TCS结合来增大TCS在液相中的浓度。挥发性脂肪酸（Volatile fatty acids,VFAs）既可作为有机质参与液相中TCS的吸附,也可以改变溶液p H值,继而改变TCS在污泥固液两相中的分配,使K_d由10957.66 L/kg降低至7833.15 L/kg。在4-6的p H变化范围内,K_d由5404.01 L/kg增大至8946.43 L/kg;而在6-9范围内,K_d又降低至5404.01L/kg。p H除了可以通过改变污泥与TCS间的静电作用力外,还能间接影响溶液中的有机质浓度以及改变TCS在溶液中的溶解度来影响TCS在污泥固液两相中的浓度分布。NH₄⁺-N通过降低污泥固相部分与TCS间的静电力并促进污泥与TCS间的氢键形成,使K_d由8865.13 L/kg增大至12264.93 L/kg。温度可通过直接影响在溶液中的溶解度、间接影响溶液中的有机质浓度来改变TCS在污泥两相中的分布,使K_d由3858.03 L/kg降低至1876.32 L/kg。（2）关于不同性质的污泥对TCS在污泥固液两相分配的影响以及不同污泥结构对TCS吸附影响的分析结果表明,污泥中有机质浓度对TCS固液分配系数变化的影响较大,且有机质含量的差异是导致污泥吸附位点对TCS吸附能力不同的主要原因。初级处理污泥的总固体含量（Total solid,TS）与TCS的K_d成正相关。活性污泥、厌氧消化污泥TS的增加使K_d分别由9971.43 L/kg降低至4676.87 L/kg以及由3220.39 L/kg降低至748.08 L/kg。而浓缩污泥和脱水污泥TS的增加使K_d分别由6285.56 L/kg增大至20130.12L/kg以及由11409.27 L/kg增大至14837.02 L/kg。另一方面,受到各吸附位点中有机质浓度的影响,TCS主要吸附在微生物细胞内和残余沉淀物,而在溶解型胞外聚合物（Soluble extracellular polymer substance,S-EPS）、松散结合型胞外聚合物（Loosely bound extracellular polymer substance,LB-EPS）、紧密结合型胞外聚合物（Tightly bound extracellular polymer substance,TB-EPS）中的分布较少。此外,S-EPS、LB-EPS和TB-EPS对TCS的吸附能力也存在差异,其中TCS在厌氧消化污泥S-EPS中的占比最多,而在其他类型的污泥中的TB-EPS中的占比最大。（3）通过将添加0、100、200和500 mg/kg TCS的剩余活性污泥（Waste activated sludge,WAS）在中温（35±2℃）条件下分别进行厌氧消化来探究TCS对WAS厌氧消化过程有机质消耗、产酸和产甲烷的影响。结果表明,TCS可促进污泥厌氧消化过程中有机质的释放以及产酸过程,但抑制产甲烷过程。添加500 mg/kg TCS反应器的VFAs浓度最大为2.51 g/L,而200、100和0 mg/kg TCS反应器中的VFAs浓度分别为2.13、1.80和1.65 g/L。与0 mg/kg TCS空白对照反应器相比,浓度为100、200和500 mg/kg TCS的反应器中的甲烷抑制率分别为11.11%,21.14%和28.71%。其中,TCS通过增强乙酸激酶（Acetate kinase,AK）、一氧化碳脱氢酶（Carbon monoxide dehydrogenase,CODH）的活性促进产酸,同时抑制了产甲烷过程中辅酶F₄₂₀活性以抑制产甲烷过程。基于16S r RNA基因测序分析微生物群落结构,发现添加TCS增大了典型产酸微生物Romboutsia、Terrisporobacter（土孢杆菌属）、Clostridium sensu stricto 13（梭菌属）和Petrimonas（理研菌属）等的相对丰度,但是降低了产甲烷微生物Euryarchaeota（广古菌门）的相对丰度。（4）通过PCA对WAS厌氧消化过程中影响TCS固液分配的因素（pH、SCOD、NH₄⁺-N、多糖、蛋白质、VFAs和挥发性固体（VS）降解率）进行分析。TCS在厌氧消化0-2天由于上清液中有机质的消耗以及在p H和NH₄⁺-N的复合作用下使得TCS倾向于从液相迁移至固相中;2-6天范围内,K_d主要在p H、VS降解率、TS和VS的作用下逐渐降低;消化6天以后在有机质消耗和NH₄⁺-N浓度的增大进一步增强了污泥对TCS的结合力,使TCS再次迁移至固相中。消化10天后厌氧消化过程中的关键指标变化幅度减缓,使得K_d在10天至厌氧消化结束期间保持相对稳定。更多还原

【Abstract】 With the consumption increase of medicines,cosmetics,and health products in China,more and more emerging organic matters enter the municipal wastewater treatment systems,causing problems of emerging containments pollution concerned by current environmrnt field.In particular,hydrophobic emerging containments are difficult to be removed by traditional wastewater treatment technologies due to their high biological toxicity and easy accumulation in the sludge.Anaerobic digestion can realize the stabilization,harmlessness and reduction of sludge and can recover resources through biogas and other forms.Study the migration of hydrophobic emerging containments（the typical antibacterial agent triclosan（TCS）as a representative）in solid and liquid phases is of great significance to the removal of such containments in the process of anaerobic digestion of sludge.This work explored the impact of TCS on the performance of anaerobic digestion,investigated the effects of key factors in the solution of the sludge,properties of the sludge and adsorption sites of sludge on TCS adsorption,and analyzed the rule of TCS migration in anaerobic digestion by using principal component analysis（PCA）.（1）The influences and mechanisms of organic matters,p H,ammonia nitrogen（NH₄⁺-N）and temperature on the distribution of TCS between the solid and liquid phases were evaluated and analyzed.The results showed that protein in the solution combined with TCS through hydrophobic interaction and hydrogen bonding to promote the enrichment of TCS in the liquid phase,and the solid-liquid partition coefficient（K_d）was significantly reduced from 12645.92L/kg to 56.02 L/kg.The increase of polysaccharide concentration reduced K_d from 16026.44L/kg to 8444.06 L/kg.The increase in the concentration of humic acid（HA）reduced the K_dfrom 9034.31 L/kg to 7244.75 L/kg.Polysaccharides and HA were combined with TCS through hydrogen bonding force to increase the concentration of TCS in the liquid phase.Volatile fatty acids（VFAs）can not only be used as organic matter to participate in the adsorption of TCS in the liquid phase,but also can change the p H value of the solution to reduced K_d from 10957.66L/kg to 7833.15 L/kg.K_d increased from 5404.01 L/kg to 8946.43 L/kg in the range of 4-6 of p H,but decreased to 5404.01 L/kg in the range of 6-9.In addition to changing the electrostatic force between the sludge and TCS,p H can also indirectly affect the concentrations of organic matters and the solubility of TCS to affect the distribution of TCS.NH₄⁺-N reduced the electrostatic force between the solid of the sludge and TCS and promotied the formation of hydrogen bonds between the sludge and TCS to increase K_d from 8865.13 L/kg to 12264.93L/kg.Temperature affected the solubility of TCS in the solution directly and affected the concentrations of organic matters in the solution indirectly to reduce K_d from 3858.03 L/kg to1876.32 L/kg.（2）The influence of sludge characteristic on the solid-liquid distribution of TCS and the influence of different sludge structures on TCS adsorption were analyzed,and the results showed that the concentration of organic matters in the sludge had a great influence on the change of TCS solid-liquid partition coefficient,and the difference of organic matter content was the main reason for the different adsorption capacity of sludge adsorption sites on TCS.The total solid content（TS）of primary sludge had positively correlated with the K_dof TCS.The increase in TS of activated sludge and anaerobic digested sludge reduced K_d from 9971.43 L/kg to 4676.87 L/kg and from 3220.39 L/kg to 748.08 L/kg,respectively.The increase in TS of concentrated sludge and dewatered sludge increased K_d from 6285.56 L/kg to 20130.12 L/kg and from 11409.27 L/kg to 14837.02 L/kg,respectively.Additionly,affected by the concentration of organic matter in each adsorption site,TCS was mainly adsorbed in the microbial cells and residuals of sludge,and relative lower in EPSs.The TCS adsorption capacity of S-EPS,LB-EPS and TB-EPS was also different.TCS accounted for the largest proportion in S-EPS of digested sludge,but for the largest proportion in TB-EPS in actavited sludge,concentrated sludge and dewatered sludge.（3）The waste activated sludge（WAS）added with 0,100,200 and 500 mg/kg TCS was anaerobic digested at medium temperature（35±2℃）to investigate the influence of TCS on the organic matter consumption,acid production and methane production.The results showed that TCS can promote the release of organic matter and the process of acid production in the anaerobic digestion of sludge,but inhibit the process of methane production.The maximum VFAs accumulation was recorded in the 500 mg/kg with concentration of 2.51 g/L,while the VFAs concentrations in the 200,100,and 0 mg/kg TCS reactors were 2.13,1.80,and 1.65 g/L,respectively.Compared with the 0 mg/kg TCS control reactor,the methane suppression rates in the reactors with concentrations of 100,200 and 500 mg/kg TCS were 11.11%,21.14%and28.71%,respectively.TCS promoted acid accumulation by enhancing the activities of acetate kinase（AK）and carbon monoxide dehydrogenase（CODH）,but inhibited the activity of coenzyme F₄₂₀ in the process of methanogenesis to inhibit the production of methane.Based on16S r RNA gene sequencing analysis of the microbial community structure,it was found that the addition of TCS increased the relative abundance of typical acid-producing microorganisms such as Romboutsia,Terrisporobacter,Clostridium sensu stricto 13 and Petrimonas.However,it reduced the relative abundance of the methanogenic microorganism such as Euryarchaeota.（4）PCA was used to analyze the factors（p H,SCOD,NH₄⁺-N,polysaccharide,protein,VFAs and VS degradation rate）that can affect the solid-liquid distribution of TCS in the process of WAS anaerobic digestion.TCS tended to migrate from the liquid phase to the solid phase in the first two days of anaerobic digestion due to the consumption of organic matters in the supernatant and the combined effect of NH₄⁺-N and p H.On day 2-6,K_d gradually decreased caused by p H increase,VS degradation rate,TS and VS.After that,the concentration of NH₄⁺-N and VFAs were further changed to enhance the binding force of sludge to TCS,thus TCS migrated to the solid phase again.The reaction stopped at the final stage and keep K_d relatively stable.更多还原