【作者】 陆谢娟；

【导师】 章北平；

【作者基本信息】 华中科技大学 ， 市政工程， 2010， 博士

【摘要】 我国南方许多城市污水的BOD、COD浓度都比较低,普遍存在碳源不足的问题,使用传统活性污泥工艺处理时由于碳源不足而脱氮效率较低,若排放水体则存在富营养化潜在危险,若增加深度处理则存在运行成本高、占地面积大、脱氮也不彻底等问题。而新的生物脱氮工艺又不成熟,工程应用上存在很多问题,因此低C/N比污水的高效脱氮成为当今水处理技术上的一个难题。论文针对我国南方城市普遍存在的低C/N比污水现状,克服目前膜生物反应器应用于污水回用存在的脱氮不彻底问题,开发了连续流一体化间歇曝气膜生物反应器(Intermittent-aeration Membrane Biological Reactor, IMBR)。IMBR集曝气、沉淀、膜滤于一体,通过三相分离器将反应区与膜室结合形成一体化构造来强化脱氮,实现污泥自回流,节省污泥回流费用,同时由于反应器上部进水中有机物的不断补充,满足反硝化所需碳源,降低了投加碳源的运行成本,提高了脱氮效果。论文的主要研究内容与结果如下：(1) IMBR降污效能及各运行参数对反应器脱氮效果的影响研究表明：工况Ⅱ(曝气2h,搅拌2h)对COD、NH4+-N、TN、SS具有较好的去除效果,系统出水完全满足《城市污水再生利用城市杂用水水质》(GB/T18920-2002)的要求,工况Ⅱ为三种工况下的最优运行工况。在工况Ⅱ运行条件下,随着HRT从4h增大到8h时,COD、氨氮和总氮的去除效果明显提高,当HRT增大到12h时,COD的去除效果反而下降,氨氮和总氮的去除效果有微小提高,建议HRT控制在8h左右；随着进水COD浓度和C/N值的升高,出水COD、氨氮与总氮浓度下降,其中总氮去除效果呈明显上升趋势；通过DO、ORP及pH曲线上A点可以判断曝气过程中碳氧化阶段结束及硝化反应的开始,通过DO降至零点及ORP、pH曲线上B点可以判断搅拌过程中硝化反应结束及反硝化开始,通过ORP曲线的硝酸盐膝(C点)和pH曲线的硝酸盐峰(C点)判断反硝化结束与厌氧释磷开始。(2) IMBR在不同工况的同步硝化反硝化脱氮研究表明：低溶解氧条件下IMBR在工况Ⅰ(持续曝气)、工况Ⅱ(曝气2h,搅拌2h)和工况Ⅲ(曝气2h,搅拌1h)中均存在SND现象。其中工况Ⅲ的SND脱氮效果较好,在曝气阶段的总氮平均去除率为56.38%,最大总氮去除率达到76.97%,在曝气/搅拌交替运行的完整周期内有53.96%的总氮通过SND去除。在工况Ⅲ运行条件下,随着DO浓度的增大,硝化率逐渐增大的同时,同步硝化反硝化率先增大后减小,在DO为0.5-1.0mg/L时SND脱氮效果最佳；随着C/N的增加,SND脱氮效果逐渐提高,当C/N为9时硝化反应成为脱氮过程的限制步骤,降低了TN的去除率,在C/N为7时SND脱氮效果最佳。(3)扫描电镜SEM图象表明,IMBR系统内的活性污泥絮体粗大而且密实,微生物相非常丰富,活性污泥内生长着大量的细菌、真菌、原生动物和后生动物,丰富的生物相为系统功能的稳定运行提供了有效保证。(4)根据Monod公式,推导出了IMBR在好氧条件下的同步硝化反硝化动力学模型,工况Ⅱ(曝气2h,搅拌2h)和工况Ⅲ(曝气2h,搅拌1h)的动力学模型中硝酸盐氮饱和常数KD分别为1.37mg/L和1.86mg/L,远远高于单级活性污泥反硝化过程中的饱和常数；工况Ⅲ的动力学常数A、B和KD值均大于工况Ⅱ的A、B和KD值,说明工况Ⅲ在好氧条件下的硝化速率和反硝化速率均高于工况Ⅱ,其氨氮去除效果和SND脱氮效果均优于工况Ⅱ。(5) IMBR的焓平衡及能耗评价指标分析表明：2h曝气/2h搅拌和2h曝气/1h搅拌两个工况的电耗在输入总能量中所占比例分别为53.38%和50.52%,大于进水能量所占比例,而出水和剩余污泥中能量所占比例均较低,进水中污染物的大部分能量转变成了功和热散失,污染物得到了降解；两个工况的比能耗偏高,能源利用率偏低,原因是进水中有机物浓度明显偏低,小试处理规模较小、供需氧不平衡所致,要提高能耗利用率,应改善供需氧平衡,并尽量减少剩余污泥量。更多还原

【Abstract】 The BOD, COD concentrations are relatively low in many cities sewage in south China and the carbon source is insufficient. When the conventional activated sludge process was used to treatment the low C/N ratio urban sewage, the nitrogen removal efficiency was low because the lack of low carbon. If the effluent excluded Natural water, the eutrophication potential danger existed. If the advanced treatment was added in the conventional activated sludge process, the running costs was high, and the area was large and nitrogen removal was not complete. However the new biological nitrogen removal process was immature and there was many problems on the engineering application. So the high nitrogen removal in the low C/N ratio urban sewage treatment technology became a problem.Aim at situation of the low C/N ratio urban sewage in south China widely and in order to solve the problem of incomplete nitrogen removal in wastewater reuse by MBR, the Integrated Intermittent-aeration Membrane Biological Reactor (IMBR) has been developed. IMBR set of aeration, sedimentation, membrane filtration in one, through the three-phase separator to integrating the reaction zone and membrane separation zone to strengthen nitrogen removal. This structure can achieve the sludge automatic return back to save the sludge return costs. The continuous influent from the reactor top can meet the required denitrification carbon source to improve nitrogen removal and reduce the running costs of adding carbon source. The main results are as follows.(1) The pollutants removal efficiency of IMBR and the operating parameters on the effect of nitrogen removal study showed that the COD, NH4+-N, TN and SS removal effect of IMBR under the conditionⅡ(2 hours aeration and 2 hours agitation) had better. The effluent quality of IMBR could meet the standard of the reused water quality criterion (GB/T18920-2002). The conditionⅡwas determined the optimal condition for the three operating conditions. With the hydraulic retention time (HRT) increased from 4h to 8h, the COD, NH4+-N and TN removal significantly improved under the conditionⅡ. When the HRT was increased to 12h, the COD removal effect declined and ammonia nitrogen and total nitrogen removal increased slightly. So the HRT of 8h had recommended. As the influent COD concentration and C/N ratio increased, the COD, NH4+-N, TN concentrations in the effluent declined, and TN removal effect significantly improved. Through point A on the curve of the DO, ORP and pH, the end of the carbon oxidation process and the start of nitrification had determined. Down to zero with the DO and through point B of ORP, pH curve, could determine the end of nitrification and the start of denitrification. And through the nitrate curve knee (point C) of ORP and the nitrate peak (point C) of pH curve could determine the end of denitrification and the start of anaerobic phosphorus release.(2) The simultaneous nitrification and denitrification (SND) studies of different working conditions in IMBR showed that SND existed in the working conditionⅠ(continuous aeration), working conditionⅡ(aeration 2h, agitation 2h) and working conditionⅢ(aeration 2h, agitation 1h) under the low dissolved oxygen conditions.In which SND removal effect of the conditionⅢhad best and the average TN removal rate was 56.38%, maximum TN removal rate reached 76.97% in the aeration phase. The TN removal by SND was 53.96% in the alternating running cycle with the aeration and mixing. With the increase of DO concentration, the nitrification rate increased and SND rate first increased and then decreased under the working condition III. The SND removal effect was best with the DO concentration of 0.5-1.0mg/L. With the C/N ratio increased, the SND removal effect was increased gradually. When the C/N ratio was 9, nitrification became limiting step in denitrification process the removal rate of TN reduced. The SND removal effect was best with the C/N ratio of 7.(3) The scanning electron microscope (SEM) images showed that the activated sludge floc within the system was bulky and dense. The variety of microorganisms was found in IMBR by the observation of microscope and there were growth of a large number of bacteria, fungi, protozoa and few micro metazoans. This provided an effective guarantee to the normal operation of the IMBR system.(4) According to Monod equation, the kinetic models of SND under aerobic conditions of IMBR were achieved. The nitrate saturation constant KD in the kinetic model of SND under condition II (aeration 2h, agitation 2h) and condition III(aeration 2h, agitation 1h) were 1.37mg/L and 1.86mg/L. It was found KD on the conditions of SND was greater than that of denitrification proeess in general model for single-stage activated sludge system. The kinetic constants A, B and KD of the condition III were greater than A, B and KD of the conditionⅡ. It showed that the nitrification rate and denitrification rate of the condition III were higher than those of the condition II under aerobic conditions. Also it showed that the SND removal effect of the condition III was better than the conditionⅡ.(5) Energy (enthalpy) balance analysis and evaluation of energy consumption in IMBR proeess showed that power consumption of the condition II and the condition II in the proportion of total energy inputs were 53.38% and 50.52% and higher than the proportion of influent energy. The effluent and sludge were lower proportion of energy. Most of the energy of influent contaminants was transformed into work and heat loss and degradation of pollutants had been thoroughly. Specific energy consumption of two conditions were high and energy efficiency was low because of many reasons, such as low influent concentration of organic pollutants, a smaller experiment scale and oxygen supply and demand imbalance. So it should improve the oxygen supply and demand balance and minimize the amount of excess sludge to improve energy efficiency.更多还原