【作者】 何岩；

【导师】 赵由才； 周恭明；

【作者基本信息】 同济大学 ， 环境工程， 2008， 博士

【摘要】 为了提高矿化垃圾反应床对渗滤液的处理能力,同时阐明其对污染物的降解转化机制,本课题主要从工艺优化和降解机制两个方面进行了研究,包括塔式矿化垃圾反应床小试、中试和实际工程运行的工艺参数优化;废铁屑、钢渣、蘑菇渣、秸秆分别作为改性剂的工艺强化;废铁屑固定床耦合矿化垃圾反应床的工艺组合优化;强化混凝处理渗滤液尾水的可行性;反应床体系中氨氮和磷的转化机制以及反应床体系中微生物种群的分子水平分析。通过正交试验研究了固液比、进水COD浓度和运行周期对塔式矿化垃圾反应床处理填埋场渗滤液的效能影响。在温度为10-37℃条件下,固液比是影响体系污染物去除性能的关键因素,最佳的工艺运行参数为:固液比大于50∶1,进水COD小于8000 mg/L,运行周期小于3h。现场中试研究表明,在温度为10-37℃,水力负荷为0.267-0.444 m³/m³_矿化垃圾·d条件下,出水COD和氨氮基本上满足国家二级排放标准。实际工程系统对填埋场渗滤液中的污染物去除效果相对较差,分析认为主要和床体填充的矿化垃圾性质以及处理渗滤液的可生化性有关。在固液比为10∶1,运行周期为3h,水力负荷为0.08 m³/m³_矿化垃圾·d条件下,分别采用废铁屑、钢渣、蘑菇渣、秸秆作为改性剂进行矿化垃圾反应床处理填埋场渗滤液的工艺强化研究。从工程实际应用角度出发,认为废铁屑是相对较为理想的一种改性剂。铁屑固定床耦合塔式反应床处理填埋场渗滤液的工艺组合优化研究表明,前置铁屑固定床和间歇曝气沉淀具有明显强化反应床体系去除COD和氨氮的能力,出水COD小于150mg/L,氨氮小于5mg/L。后置铁屑固定床和间歇曝气沉淀不能有效强化去除塔式反应床出水中的COD。随着铁屑内电解反应器的不断完善,前置铁屑固定床和间歇曝气沉淀可作为强化矿化垃圾反应床处理填埋场渗滤液的有效途径。聚合氯化铝、氯化铁和硫酸铝强化混凝处理渗滤液尾水的研究表明,氯化铁强化混凝的效果最佳,硫酸铝的效果最差。氯化铁的最佳混凝条件为:pH4.5、FeCl₃ 1500 mg/L、PAM 15mg/L、磺酸类化合物5 mg/L和硅藻土1500 mg/L,其COD去除率为60.9%;聚合氯化铝和硫酸铝的最佳COD去除率分别为50%-53%和34.4%。强化混凝不能实现对渗滤液尾水的有效处理。矿化垃圾对氨氮具有“易吸附、难解吸”的特点,矿化垃圾反应床对氨氮的吸附是在瞬间（<10min）完成的,且难以解吸。可用Freundlich方程比较准确地描述矿化垃圾对氨氮吸附的整个过程,其中n值在0.1-0.5之间,表示氨氮吸附容易进行。矿化垃圾反应床对氨氮的转化研究可知,床体中的阳离子交换位点仅仅起暂时贮存氨氮作用,随即主要通过硝化作用实现其氨氮吸附活性的生物再生。通过配水期和落干期的交替循环,反应床完成对氨氮的吸附和生物转化再生。因此,分析认为矿化垃圾反应床的氨氮去除性能与其运行年限无关。低的总氮去除率是由于其反硝化和厌氧氨氧化效果差所致。采用修正的Hedley磷素分级方法对矿化垃圾中磷的赋存形态特征进行研究。以NaOH-P和Dil.acid-P构成的中度活性磷为矿化垃圾中磷的主要赋存形态,占TP的74.9%,说明矿化垃圾中磷的可利用率相对较高。塔式反应床体中不同磷素形态的时空动态变化表明,矿化垃圾反应床对填埋场渗滤液中磷的去除过程也是其自身富集磷的过程,增加的磷素主要以Dil.acid-P和NaOH-P形态存在,而且主要集中在塔式反应床的上层床体中。据此推断矿化垃圾反应床对填埋场渗滤液中磷的转化主要是通过吸附和生成以多羟基磷灰石为主要形式的化合物而固定。鸡粪（含磷较高）和稻草（含磷较低）两种典型有机物料均能显著活化矿化垃圾中的磷,而且鸡粪的磷活化效果优于稻草;NaOH-P、Dil.acid-P和Conc.acid-P是矿化垃圾活化磷的主要来源。建立了一种适合于矿化垃圾基因组DNA提取的方法,即TENP buffer/PBSbuffer-Bead beating/Proteinase K/SDS-Sephadex G-200 spin column的组合。矿化垃圾反应床体系的微生物分子水平分析发现,矿化垃圾是极端环境微生物的载体,包括嗜盐、嗜碱、嗜热和嗜冷微生物,说明正是由于矿化垃圾反应床中含有这些具有特殊代谢系统的极端微生物才使其具有强的污染物降解能力,证实了矿化垃圾是一种性能优越的生物介质。反应床体系中的细菌以芽孢杆菌属、变形菌属和动球菌属为优势菌属,古菌以甲烷八叠球菌属和甲烷嗜热菌属为优势菌属。运行良好的反应床体系中的细菌主要包括芽孢杆菌属、微杆菌属、放线菌属、动球菌属、γ-变性菌属以及未分类的氮转化细菌;古菌包括euryarchaeote、methanomicrobia、产甲烷archaea、Crenarchaeote和一种未知菌。最后,关于进一步工作的方向包括高效生物反应器的开发、总氮去除率的提高和矿化垃圾微生物分子水平的深入研究进行了简要的讨论。更多还原

【Abstract】 The objectives of this research were to perfect the removal performance and explain the removal mechanisms of the aged-refuse-based reactor in treating landfill leachate. The optimization and operation mechanisms of the aged-refuse-based reactor for the treatment of landfill leachate were mainly investigated, including the determination of the optimized parameters from the operation of the bench-scale, pilot-scale and full-scale stratified reactors; the improvement of the aged-refiise-based reactor in treating landfill leachate by addition of inducing materials such as waste iron scraps,steel slag,mushroom residual and straw individual; the best hybrids of the iron-scraps-fixed reactor and the aged-refuse-based reactor; the feasibility of enhanced coagulation in polishing effluent from the aged-refuse-based reactor; the transformation mechanisms of ammonium and phosphrous in the reactor and the molecular microbial community profile during the operation of the reactor.The influences of operating parameters including the volume ratio of aged refuse and influent, the influent COD concentration and the operating cycles on the removal performance of the landfill leachates treatment with the stratified aged-refuse-based reactor were investigated by the Orthogonal Test. The results indicated that the volume ratio of aged refuse and influent was crucial for the operation of the reactor at ambient temperature of 10-37℃. The optimized operational parameters were the volume ratio of aged refuse and influent greater than 50, the influent COD of less than 8000 mg/L and the operation cycle of below 3 h. The pilot-scale experiments showed that under the operating temperature of 10-37℃and the hydraulic load of 0.267-0.444 m~3/ m~3.d, the COD and ammonium of the effluent could conform to the requirements of Second Grade National Discharge Standard generally. The relatively low biomass in the aged refuse and the poor biodegrability of the leachate used in the full-scale reactor could be mainly responsible for its unsatisfactory performances.The improvement of aged-refuse-based reactor in treating landfill leachate was tested by addition of inducing materials such as waste iron scraps, steel slag, mushroom residual and straw individually. The experiments were conducted with the volume ratio of the aged refuse and the influent of 100, the operating cycle of 3 h and the hydraulic load of 0.08 m~3/m~3.d . The results indicated that waste iron scraps could notably improve the removal performance of the aged-refuse-based reactor in terms of COD and color; the addition of the steel slag could facilitate the removal of COD,color and total phosphrous, while lower the removal capacity of the reactor in ammonium and total nitrogen; The enhanced removal of COD and color by the mushroom residual could not be attained until long time operation of the reactor; likewise, the increased removal of COD,color, ammonium,total nitrogen and total phosphrous by straw could not be achieved until its termination of self-degradation. Therefore, waste iron scrap was considered a kind of proper inducing material in terms of engineering application.The optimized hybrids of the iron-scraps-fixed reactor and the aged-refuse-based reactor were investigated. The results showed that the preceding iron-scraps-fixed reactor and the intermittent aeration-sedimentation could improve the removal performance of the aged-refuse-based reactor in terms of COD and ammonium; the COD and ammonium concentration in the effluent were 150mg/L and 5mg/L, respectively. The posterior iron-scraps-fixed reactor and the intermittent aeration-sedimentation could not enhance the removal capacity of the stratified aged-refuse-based reactor, which could be explained by the fact that the COD removal pathway of iron scraps was discontinued due to the rising potential from high-level nitrate and the refractory soluble COD in the effluent. With the gradual improvement in the iron-scrap-fixed reactor, the preceding iron-scraps-fixed reactor and the intermittent aeration-sedimentation could be considered a promising way in bettering the removal performance of the aged-refuse-based reactor.The feasibility of enhanced coagulation in polishing the effluent from the aged-refuse-based reactor was tested regarding polymer aluminum chloride (PAC), ferric chloride and aluminum sulfate. The results demonstrated that the enhanced coagulation of ferric chloride was the best and that of aluminum sulfate was the worst for polishing the effluent. The optimal coagulation condition of ferric chloride was pH4.5, ferric chloride dose of 1500 mg/L, PAM dose of 15 mg/L. sulfonic-group compound dose of 5 mg/L and diatomite dose of 1500 mg/L. The maximum COD removal of 60.9% was obtained by the ferric chloride enhanced coagulation. The best COD removal of PAC and aluminum sulfate were 50%-53% and 34.4%, respectively.The adsorption and desorption tests showed that the adsorption of ammonium by aged refuse occurred instantly and the adsorbed ammonium was stable and less exchangeable. The Freundlich isotherms could fit the adsorption trend of ammonium by aged refuse. The value of n was 0.1-0.5, indicating the adsorption of ammonium occurred easily. The synergistic transformations of ammonium within aged-refuse-based reactor indicated that the cation exchange sites only provided temporary storage of ammonium prior to subsequent nitrification. The nitrification process could be considered the predominant restoration pathway of ammonium adsorption capacity of the reactor. The wetting cycle allows ammonium to be adsorbed onto aged refuse. During the subsequent drying cycle, the oxygen infiltrates in the reactor and ammonium is mostly converted to nitrate via nitrification. Hence, it could be concluded that there was no expire for the aged-refuse-based reactor in terms of ammonium removal. The low removal of total nitrogen could be mainly attributed to poor denitrification and anaerobic ammonium oxidation (anammox).A modified Hedley phosphorus (P) fractionation method was used to investigate the quantities and proportions of P fractions in aged refuse. The results indicated that the moderately available P (sum of hydroxide and dilute acid fractions) was the predominant forms and accounted for 74.9% of total P in aged refuse, indicating that the phosphorus in aged refuse had the potential of high-efficacy utilization. The temporal and spatial distributions of different P speciations in the stratified aged-refuse-based reactor showed that the phosphrous was accumulated in the reactor during the treatment of landfill leachate. The increase of phosphrous was in form of Dil.acid-P and NaOH-P. The accumulated P was mainly occurred in the upper part of the reactor. Therefore, the conclusion could be drawn that the phosphrous was removed mostly by adsorption and transformation into the precipitated combound of hydroxyl apatite. The activation effects of chicken manure (high P content) and straw (low P content) on different P forms indicated the chicken manure and straw had significant activation effects on the phosphorus in aged refuse, and the chicken manure was superior to straw in P-activation. It was found that NaOH-P, Dil.acid-P and Conc.acid-P were main sources of activitable P in aged refuse.In order to develop and validate a method for isolation of PCR-amplifiable DNA from the aged refuse samples, the orthogonal experiment was conducted to evaluate systematically the effects of various steps within each method in terms of DNA yield, purity, fragment size, humic substances contamination, PCR amplifiability using universal eubacterial and archaea 16S rDNA prime pair, and genetic diversity estimate from denaturing gradient gel electrophoresis (DGGE). The combined method of TENP buffer/PBS buffer-Bead beating/Proteinase K/SDS- Sephadex G-200 spin column was recommended.The molecular analyses of microbial community under different operation of the reactor were performed. An interesting phenomenon was discovered that the aged refuse was the carrier of extremophiles, including halophilic, alkaliphilic, thermophilic and psychrotrophic microorganism. The strong pollutant removal capacity of aged refuse could result from the high content of extremophiles, which were of the facultative metabolic pathways and the strong adaptive capacity. The predominant eubacteria within the reactor consisted of bacillus sp., proteobacterium and planococcus sp., and the chief archaea included methanosarcinales and crenarchaeote. During the optimized operation of the stratified reactor, the main eubacteria consisted of bacillus sp., microbacterium sp., actinobacteria, planococcus sp.,γ-proteobacterium and one kind of undefined N-transformation bacteria,the predominant archaea were euryarchaeote, methanomicrobia, methane-producing archaea, meihano thermophiles and one unnamed archaea. The self-immobilization of extremophiles by the carrier of aged-refuse makes it possible to treat the refractory industrial wastewater of hypersalinity and hyperalkalinity by biological pathway.In the finality, further studies were discussed in terms of the development of high-performance bioreactor, the improvement of the total nitrogen removal and the comprehensive molecular analyses of microbial community in the aged refuse.更多还原