【作者】 周真明；

【导师】 黄廷林；

【作者基本信息】 西安建筑科技大学 ， 市政工程， 2013， 博士

【摘要】 随着我国工业化和城市化进程的加快，城市河湖富营养化问题日益严重。氮磷浓度是河湖富营养化的主要限制因子，沉积物是河湖中氮磷的“源”或“汇”，因此，原位控制污染沉积物氮磷释放是控制河湖富营养化的有效措施。针对目前污染沉积物原位覆盖法中的覆盖材料存在原位再生困难、吸附的氮再释放和利用率不高等问题，本文提出了以挂膜沸石作为主要覆盖材料的原位生物/物化组合修复技术控制污染沉积物氮、磷和有机物释放，研究了该技术控制沉积物污染物释放效果、影响因素和作用机理，考察了沸石原位生物再生的可行性，分析了沸石上细菌数量变化和微生物种群结构演替特征，优化了覆盖层组成方式和规模化制备挂膜沸石方法。主要开展了以下研究。（1）研究了高效菌在沸石上的挂膜方法，制得挂膜沸石。研究发现，将从沉积物中分离、筛选得到的2株高效异养硝化细菌WGX10和WGX18（均属于芽孢杆菌属，Bacillus sp.）和2株高效好氧反硝化细菌HF3和HF7（均属于不动杆菌属，Acinetobacter sp.）等4株菌液按等体积比混合，制得混合菌液；再将其与灭菌原水按照体积比1:9混合，制得混合液；将天然沸石放置混合液中，在25-30℃、DO浓度2³mg·L^-1以上条件下进行人工曝气挂膜培养2³d，即可制得挂膜沸石。（2）试验研究了挂膜沸石覆盖对沉积物污染物释放的控制能力和效果。室内模拟试验研究结果表明，10kg·m^-2挂膜沸石覆盖对上覆水体TN削减率达90%以上，对表层（0¹8cm）沉积物TN削减率为10%，对表层（0⁸cm）沉积物TP固定率为13%；现场原位试验研究结果表明，2kg·m^-2挂膜沸石覆盖对上覆水体的TN和COD平均削减率为36%和41%，对上覆水体和表层（0²0cm）沉积物的TP平均固定率分别为35%和13%；可见，挂膜沸石覆盖不仅有效地控制沉积物氮、磷和有机物释放，而且进一步削减沉积物氮负荷，是原位修复污染沉积物的有效技术。（3）研究了影响挂膜沸石覆盖控制沉积物污染物释放的技术关键控制因子。上覆水体DO浓度、挂膜沸石覆盖强度、碳源等是主要影响因素；上覆水体DO浓度过高或过低都会影响生物脱氮效果，最佳DO浓度为1⁴mg·L^-1；挂膜沸石覆盖强度越大，控制效果越好，应结合沉积物污染程度、控制效果要求及成本等设计覆盖强度；碳源减少使生物脱氮效果降低。（4）研究了挂膜沸石覆盖控制沉积物污染物释放的作用机理。主要依靠生物、化学和物理协同作用削减氮负荷，沸石的物理吸附和化学离子交换快速吸附氨氮；高效菌的生物硝化反应将吸附的氨氮转化为硝氮，实现沸石原位生物再生，同时其生物反硝化反应将硝氮转化为N2。主要依靠物理吸附和化学沉淀反应固定磷。（5）研究了挂膜沸石上细菌数量变化和微生物菌群结构演替规律。挂膜沸石上硝化细菌数量随着碳源的减少而减少，反硝化细菌随着碳源的减少及上覆水体DO浓度增加(大于3mg·L^-1)而减少，可见碳源和上覆水体DO浓度是影响挂膜沸石上硝化菌和反硝化菌生长的主要因子；高效菌一直存在挂膜沸石上，且都是优势菌，高效菌与土著菌存在竞争，土著优势菌的种类不断更替，新增土著优势菌中，沙雷氏菌和代夫特菌具有脱氮功能，细菌形态从球杆状变为杆状。（6）优化了覆盖层组成方式。覆盖层最佳组合方式是挂膜沸石层在下、河沙层在上；河沙层作用是提高挂膜沸石层吸附氨氮能力、强化挂膜沸石层生物脱氮作用、物理掩蔽未被挂膜沸石覆盖的沉积物；挂膜沸石与河沙组合覆盖可以降低挂膜沸石覆盖强度，从而减少了成本。（7）研究确定了挂膜沸石规模化制备方法，在扬州鸿泰支河应用了挂膜沸石与河沙组合覆盖修复技术控制沉积物污染物释放，覆盖层组成方式为上层河沙（5mm厚）、中层挂膜沸石（20mm后）和下层河沙（10mm厚）。应用结果表明：组合覆盖技术对上覆水体TN和CODCr平均削减率分别为61%和34%，对TP的平均固定率为37%；可见，规模化制备挂膜沸石方法是可行的。更多还原

【Abstract】 With the rapid development of industrialization and urbanization, eutrophicationof the urban rivers and lakes is increasingly more serious in China. Nitrogen （N） andphosphorus （P） concentrations are the main limiting factors for eutrophication of therivers and lakes, and sediment plays an important role in eutrophication because it wasregarded as a source or a sink for N and P of the rivers and lakes. Therefore, in situreducing N and P released from sediment will be an effective solution for controllingeutrophication of the rivers and lakes. Currently, the capping material of in situcontaminated sediment capping may have the following issues:（1） in situ regeneration;（2） secondary release of nitrogen from active adsorbent;（3） limited utilization rate ofactive adsorbent. In order to resolve these issues, in situ combined biological andphysicochemical technology with biozeolite as main capping material was proposed toreduce N, P and organics released from sediment in the study. The efficiencies,mechanisms and the main influences of controlling contaminant released fromsediment using the technology were examined through laboratory and field scaleincubation experiments. The feasibility of in situ biological regenerating theammonium （NH4+-N） adsorption capacity of zeolite was investigated. The successivechanges in microbial community structure, nitrifiers and denitrifiers number on thebiozeolite were analyzed. The composition methods of capping layer and the methodsof large-scale preparation of biozeolite were optimized. The study mainly carried out as the follows:（1） The preparation of biozeolite: To obtain the bacterial consortium, twoheterotrophic nitrifiers WGX10and WGX18（Bacillus sp.） and two aerobic denitrifierHF3and HF7（Acinetobacter sp.） isolated from contaminated sediment were enrichedrespectively, and then mixed in equal proportion. The natural zeolite of a certainamount were put in mixed liquor of the bacterial consortium suspension and sterilizedraw water at1:9in volume for2³days under the condition of25³0℃anddissolved oxygen （DO） above2³mg L^-1via artificial aeration until the biofilmformation process was finished.（2） The efficiencies of the technology: The laboratory sediment incubationexperiment results showed that the reduction efficiency of total nitrogen （TN） ofoverlying water using capping with biozeolite of the dose rates of10kg m^-2was morethan90%, the TN reduction efficiency of sediment core （0¹8cm） was10%, and thetotal phosphorus （TP） fixation efficiency of sediment core （0⁸cm） was13%. Thefield sediment incubation experiment results showed that the average reductionefficiencies of TN and chemical oxygen demand （COD） of overlying water by cappingwith biozeolite dose rates of2kg m^-2were36%and41%, respectively, and the TPaverage fixation efficiency of overlying water and sediment core （0²0cm） was35%and13%, respectively. Therefore, biozeolite capping could not only effectively inhibitN, P and organics released from sediment, but also can further reduce some of N fromsediment, and is an effective technology for in situ remediating contaminated sediment.（3） The key factors of the technology: The DO concentrations of overlying water,the dosage of biozeolite and carbon source were the main factors of the technology.The efficiencies of biological nitrogen removal were influenced by too high or low DOconcentrations, and the optimal concentration range of DO was between1⁴mg L^-1.The higher the dosages of biozeolite were, the better efficient reduction of contaminantreleasd from sediment were, and in order to design the dosage of biozeolite, pollutionlevel of sediment, requirement of reduction efficiency and technology cost should betaken into consideration. The reduction of carbon source was the major reason for thedecrease of biological nitrogen removal.（4） The mechanisms of the technology: The N removal mainly depends on biological, physical and chemical processes. NH4+-N is quickly adsorbed by biozeolitethrough physical adsorption and chemical ion exchange. The adsorbed NH4+-N isgradually desorbed from biozeolite and transformed to NO3--N through biologicalnitrification, indicating that in situ biological regenerating the ammonium （NH4+-N）adsorption capacity of zeolite is feasible. The P fixation mainly depends on physicaland chemical processes.（5） The successive changes in microbial community structure, nitrifiers anddenitrifiers number on the biozeolite: The reduction of carbon source was the majorreason for the decrease of nitrifiers number. The reduction of carbon source and toohigh DO concentration (more than3mg L^-1) were the primary cause for the decreaseof denitrifiers number. Therefore, the DO concentration and carbon source are the mainfactors for the growth of nitrifiers and denitrifiers. Bacillus sp. and Acinetobacter sp.were still present on the biozeolite and were dominant bacteria. There was competitionbetween indigenous bacteria and isolated bacteria, and the indigenous dominantbacteria progressed continually. Moreover, two indigenous aerobic denitrificationstrains （Delftia sp. and Serratia sp.） were found on the biozeolite. The bacterial shapesvaried from sphere bacilli form to rod-shaped.（6） The optimization of the composition methods of capping layer: The optimalcombination method of biozeolite and sand was to put biozeolite under the fine sand.The purpose of sand on the upper layer are: to improve the NH4+-N adsorption capacityof biozeolite capping layer; to strengthen biological denitrification of biozeolitecapping layer; to cover the sediment that missed the coverage by biozeolite. Thecombination capping of biozeolite and sand could decrease the dose rate of biozeoliteand reduce the cost.（7） The large-scale preparation method of biozeolite was established. Thecombination capping technology of biozeolite and sand was applied for controllingcontaminant released from sediment in Hongtai River at Yangzhou City. Thecomposition method of capping layer from top to bottom was sand layer （the thicknessof5mm）, biozeolite layer （the thickness of20mm） and sand layer （the thickness of10mm）. The results of the average reduction efficiencies of TN, TP and COD ofoverlying water using the combination capping of biozeolite and sand were61%and 34%, respectively, and the TP average fixation efficiencies was37%. Therefore, thelarge-scale preparation method of biozeolite is feasible.更多还原