【作者】 刘礼祥；

【导师】 沈韫芬； 章北平；

【作者基本信息】 华中科技大学 ， 市政工程， 2007， 博士

【摘要】 针对我国南方城市污水水质特征及污水处理工艺存在的问题,从简易污水处理思想出发,以倒置A2/O及经典SBR工艺过程及时空关系为基础,并在一体化氧化沟固液分离基础上,创造性的将三相分离器概念引入一体化同步脱氮除磷反应器,开发出新型连续流一体化生物反应器(CIBR)。CIBR通过三相分离器将反应区与沉淀区有机结合在一起,不仅实现了单池连续流恒水位进出水运行、节省污泥回流能耗,还从构造上解决一体化脱氮反应器固液分离不彻底等问题,提高了出水稳定性。研究表明:(1)CIBR兼性生化模式处理效果受水温影响较大,当水温低于12℃时,处理效果会明显下降且污泥流失严重。在低温条件下采用化学兼性生化模式,可改善污泥沉降性能,减少污泥流失,但无法改善系统硝化及脱氮效果。当水温偏低或进水NH3-N浓度较高时,单独采用兼性生化模式或化学辅助兼性生化难以满足处理要求,需要变换运行模式以提高系统硝化效果及出水稳定性。(2)CIBR间歇曝气模式最佳工艺参数为HRT为12h、MLSS为3000mg/L、SRT为15d。CIBR间歇曝气模式处理效果受到曝气/搅拌/静沉时间、曝气比、曝气功率、碳源、污泥负荷Ns及平均能耗等影响。虽然进水COD浓度较低,但由于采用连续进水方式运行,在保证充分的好氧硝化及缺氧反硝化时间条件下,控制各阶段合理的时间比例、提高平均能耗有利于获得较好的同步脱氮除磷效果。CIBR化学辅助间歇曝气模式在有机物去除上未表现出协同作用,但在脱氮除磷方面表现出一定的协同作用,并提高了出水稳定性;投加絮凝剂能在一定程度上促进了亚硝化反应,并在一定程度上提高NH3-N去除效果。(3)通过CIBR间歇曝气模式三种典型工况条件下氮形态、MLSS、COD/MLSS、COD/NOX-N及COD、NH3-N、NO3--N、NO2--N、TN、TP等时空分布规律研究表明,曝气及搅拌状态下反应器整体为完全混合状态,静沉阶段为推流流态;充分的好氧曝气与缺氧搅拌是高效脱氮的前提与保证;连续进出水不但有利于减少好氧阶段有机物异养菌对硝化自养菌的抑制作用,还可以为缺氧反硝化补充碳源,缓解进水C/N偏低对脱氮效果的不利影响;揭示了CIBR间歇曝气模式在碳源不足情况下获得高效同步脱氮除磷的理论根据。(4)受连续进水影响,CIBR间歇曝气与SBR脱氮除磷工艺在线参数变化规律有一定的区别,但CIBR间歇曝气模式有机物降解及同步脱氮除磷过程可以通过在线DO/ORP/pH曲线及dORP/dt及dpH/dt辅助曲线联合进行判断并可获得三个特征点,即易降解有机物完成点与硝化反应开始点(A点)、硝化反应完成点或停止点(B点)及反硝化反应完成点与厌氧释磷开始点(C点)。(5)多种模式交互过程易出现硝化效果下降、脱氮效率降低、释磷等现象及出水不稳定等问题,采用化学辅助间歇曝气模式可以加快系统TP去除效果恢复速度,但COD、NH3-N及TN去除效果几天内难以恢复。而采用CIBR间歇曝气模式变工况运行时,COD、NH3-N、TN及TP去除率平均值依次为76.40%、82.33%、66.24%、及70.18%,系统稳定性远远高于CIBR变模式运行。采用CIBR生物-波形潜流人工湿地生态处理组合工艺进行城市污水处理,根据季节性水质及生态单元处理功能变化调整CIBR生物单元运行工况,以进一步提高处理效果及稳定性,并降低运行能耗。CIBR生物单元四季分别采用工况II(2-1-1)、工况V(2-0-2)、工况VIII(3-1-2)及工况VII(3-2-1)运行,系统总体出水稳定达到GB18918-2002一级A排放标准。(6)为揭示CIBR生物处理工艺节能原理,建立了CIBR生物处理单元能量衡算黑箱模型和火用平衡分析灰箱模型,对CIBR生物单元用能结构和用能效率进行了研究。首次引入了火用分配系数λ概念,可以根据污水处理厂污泥处理单元需求灵活调整工艺运行参数来调节剩余污泥产量与耗散火用之间的比例,以达到降低总体运行能耗目标。在传统能量评价指标基础上,首次提出了比火用耗概念,节能的主要目的在于降低比火用耗,节省外界投入作为推动力的化学火用。通过CIBR生物单元四季比能耗、热效率、热力学效率及比火用耗指标对比分析可知,比火用耗较之比能耗、能量利用率及目的火用效率评价指标更为客观和严密。通过比火用耗及能耗折算分析表明,生物生态组合工艺节火用效率高,相比于A2/O工艺及Bardenpho工艺吨水处理电耗分别节省了37.59%及57.84%。由此可见,CIBR生物/波形潜流人工湿地生态组合处理工艺节能效率是建立在生态单元低耗脱氮除磷及CIBR生物单元变工况节能运行共同作用的基础上。更多还原

【Abstract】 In order to solve the problems encountered in the treatment of in municipal wastewater in south China, this study developed a novel continuous-flow integrated biological reactor (CIBR). To simplify the wastewater treatment process, CITR utilized the spatiotemporal sequencing relation of A2/O and conventional SBR and firstly used three-phase separator to achieve the simultaneous removal of nitrogen and phosphate in a single tank. Since the reaction zone and settling zone were integrated in CITR, the continuous water flow can be maintained at constant level, the energy consumption for sludge return was reduced, the problem of incomplete separation of solid and liquid was solved and the discharged water quality was improved. The main conclusions are drawn as follows.(1) The removal efficiency by facultative treatment in CIBR was greatly influenced by water temperature. When water temperature was below 12 oC, the removal efficiency declined sharply and the flowing out of sludge was great. When CITB was run in chemical assistant facultative mode at low temperature, the sludge settling can be improved to some extent, but the nitrification and denitrification efficiency can not be increased. When the water temperature was low or the NH3-N concentration was high, it was difficult to run CIBR in facultative mode or in chemical assistant facultative mode to attain the requirement. So, it was necessary to change the running mode to improve treatment efficiency.(2) Optimal conditions in CIBR were obtained as HRT of 12 h, MLSS of 3000 mg/L and SRT of 15 d. The treatment efficiency was influenced by the ratio of aeration, agitation, and settling time, the aeration ratio, the aerating power, the carbon source, the sludge load (Ns) and the average energy consumption. Though the influent COD concentration was low, a good simultaneous removal of nitrogen and phosphate could be achieved by the continuous influent and sufficient nitrification and denitrification. Somewhat synergistic effect on the removal of nitrogen and phosphate was obtained when CIBR was assisted by chemical intermittent aeration. The addition of coagulant attributed to nitrification and NH3-N removal.(3) The spatiotemporal distribution of nitrogen species, MLSS, COD/MLSS, COD/NOx-N, COD, NH3-N, NO3--N, NO2--N, TN and TP under the three typical working conditions in the intermittent aeration working mode of CIBR indicated that the whole reactor was in completely mixed flow in aeration and agitation phases and in plug flow in the settling phase. The sufficient aerating and anoxic agitating ensured the efficient denitrification. The continuous influent not only decreased the restraint of heterotrophic bacteria to the nitrobacteria under the aerobic phase, but also eased the negative effect of low influent C/N ratio on denitrification by supplying the carbon source for denitrification inthe anoxic phase. Efficient simultaneous removal of nitrogen and phosphorus in CIBR could be achieved under the intermittent aeration working mode.(4) The variation of parameters in CIBR were different from that in SBR due to the continuous influent. Three points for organic compounds degradation and nitrogen and phosphate removal can be obtained from the curves of DO/ORP/pH, dORP/dt and dpH/dt. They are the complete of organic compound degradation and the start of nitrification (point A), the end or pause of nitrification (point B), and the end of denitrification and the start of anaerobic phosphorus release (point C).(5) During the alternation of intermittent aeration and facultative biochemical process, nitrification and denitrification efficiency decreased, phosphorus release increased and effluent quality was often unstable. The chemical assistant intermittent aeration could accelerate the resumption of the phosphorus removal, but could not resume the removal of COD, NH3-N and TN in a short time. In CIBR under different working conditions with intermittent aeration, the average removal of COD, NH3-N, TN and TP were 76.40%, 82.33% 66.24% and 70.18%, respectively. In order to improve the treatment efficiency and to reduce the running energy consumption, the combined process of CIBR and wavy flow subsurface constructed wetland was developed to treat municipal wastewater. According to the, High efficiency and low energy consumption can be attained by adjusting the working condition of CIBR according to the seasonal variation of influent quality and the removal efficiency of ecological units. The optimal working conditions of CIBR process in each season were condition II(2-1-1), condition V(2-0-2), condition VIII(3-1-2) and condition VII(3-2-1), respectively. The effluent quality can stably reach standards of municipal wastewater treatment (GB18918-2002).(6) In order to reveal the mechanism for energy reduction in CIBR process, the energy balance black box model and exergy balance grey box model were established. The structure of energy consumption and energy efficiency in CIBR process were investigated. The distributing coefficient (λ) of exergy was used for the first time. The ratio of excess sludge and dissipation exergy can be conditioned to reduce the energy consumption based on the the requirement of sludge treatment unit of the municipal wastewater treatment plant. The specific exergy consumption conception was proposed. The aim of saving energy was to reduce the specific exergy consumption and to decrease the outside devoted exergy. The specific exergy consumption was more accurate and precise than the specific energy consumption, thermal efficiency, enthalpy efficiency and aim exergy efficiency. By the analysis of the specific exergy consumption and energy consumption, it can be concluded that the exergy consumption of the combined process was much less. Compared with A2/O process and Bardenpho process, the combined process could reduce 37.59% and 57.84% energy consumption, respectively. The high energy efficiency of the combined process was stem from the low energy consumption for the removal of nitrogen and phosphorus in ecological unit and the run of varied working conditions in CIBR.更多还原