【作者】 韩志英；

【导师】 陈英旭；

【作者基本信息】 浙江大学 ， 环境工程， 2007， 博士

【摘要】 随着我国畜禽养殖规模不断扩大，削减规模化养殖场废弃物污染负荷已经成遏制农业面源污染的关键。碳氮比例失调是养殖废水生物处理的主要限制因子。分步进水序批式反应器（SFSBR）是一种依靠多步缺氧进水补充反硝化碳源的生物脱氮强化工艺。为促进SFSBR工艺在畜禽养殖场废水处理中的应用和发展，本研究围绕SFSBR生物脱氮问题，以猪场废水为处理对象，通过实验室模拟实验，从污染物变化、污泥性状和氧化还原电位（ORP）、pH、溶解氧（DO）过程控制参数三个方面探明曝气强度、进水负荷、进水碳氮比、进水分配对SFSBR工艺特性的影响，确定SFSBR处理猪场废水生物脱氮最佳工艺参数，探明ORP、pH、DO动态变化特征，论证SFSBR内污泥颗粒化可行性。通过实验研究和理论分析，取得以下主要结果：有机污染物降解遵循一级反应关系时，去除有机物SFSBR工艺中有机物去除效率是反应时间和进水次数的函数，延长反应时间或增加进水次数有利于提高SFSBR有机物去除率；生物脱氮型SFSBR中各“非曝气—曝气”子循环发生完全反硝化—硝化时，降低最后一步进水体积分数（β）或增加换水量（V₀／V_F）有助于提高SFSBR生物脱氮效率。泥龄相同条件下SFSBR所需反应器容积小于传统A／O型SBR工艺所需容积。进水负荷、曝气强度、进水体积比、进水碳氮比直接影响进水量递减型SFSBR处理猪场废水工艺特性。两步减量进水SFSBR中，提高有机负荷（进水碳氮比随机变化）SFSBR内生物脱氮过程受到抑制；提高曝气强度利于提高SFSBR曝气阶段硝化速率，缩短硝化时间，改善生物除磷效率；降低进水体积比（＞1：1）SFSBR生物脱氮效率提高不显著，而生物除磷过程得到强化。三步减量进水SFSBR中，提高进水氮负荷（进水碳氮比固定），反硝化及生物除磷过程受到限制；提高SFSBR进水碳氮比有助于提高反应器内反硝化效率，强化生物除磷过程。SFSBR因过有机负荷硝化完全停止时和反硝化效率提高时，反应器内ORP和pH变化幅度发生特征性变化。SFSBR内污泥颗粒化具有可行性。以猪场废水为营养基质，在SFSBR内培养的颗粒污泥呈黄褐色，直径0.5～1.0mm，微生物菌相丰富。进水负荷和进水碳氮比主要影响颗粒污泥胞外多聚物（ECPs）分泌量及颗粒污泥结构，高进水负荷和高进水碳氮比条件下颗粒污泥ECPs增多，颗粒污泥结构致密。污泥微生物聚合酶链式反应-变性梯度凝胶电泳（PCR—DGGE）检测结果表明，反应器内混合污泥微生物多样性随着进水碳氮比提高而增加。正交实验结果表明不同工艺参数对颗粒污泥型SFSBR（G-SFSBR）处理猪场废水脱氮效果和污泥性状影响效应不同：氮负荷对出水氮素浓度（氨氮、亚硝态氮与硝酸盐氮浓度总和）影响最大，曝气强度对氮净去除率（NNER）影响最大，进水碳氮比对污泥体积指数（SVI）及颗粒污泥质量分数(f_0.5mm)影响最大，但进水体积比（＞1：1）对颗粒污泥质量分数(f_0.5mm)影响较小，对反应器生物脱氮效果影响不显著。G-SFSBR处理猪场废水最佳工艺条件为进水碳氮比7.0mgCOD／mgNH₄⁺-N，进水体积比3：1，进水氮负荷0.026gNH₄⁺-N／（gVSS·d），曝气强度4.2 L／（m³·s），在该实验条件下出水无机氮浓度最低、氮净去除率最高，分别为21mg／L和72％。污泥微生物PCR-DGGE检测结果表明，G-SFSBR污泥微生物种群结构稳定性较强，而脱氮参数优化对污泥微生物种群和丰度有影响，颗粒污泥及混合污泥微生物种群向优势化菌群方向发展。进水量递减型SFSBR系统内ORP、pH、DO变化与生物脱氮过程关联度与进水分配相关。SFSBR进水氨氮浓度及硝化时间与曝气强度相匹配时，ORP“氮突破点”可以指示硝化结束，ORP“硝酸盐膝”指示内源代谢显著的反硝化结束。pH“氨谷”可指示硝化结束，但其灵敏性受氨氮初始浓度和硝化时间的限制。另外，非曝气阶段ORP下降幅度及完全硝化过程pH下降幅度均可作为SFSBR工艺进水分配的控制参数。SFSBR系统内硝化过程中ORP及pH变化速率可用于硝化速率估计。DO飙升指示硝化结束，可用于曝气过程控制。进水量递减型SFSBR处理猪场废水工艺中，生物除磷主要在第1“非曝气—曝气”子循环内发生，后续“非曝气—曝气”子循环内生物除磷过程不明显，SFSBR生物除磷机制有待进一步研究。更多还原

【Abstract】 With the expansion of livestock industry, pollution control of animal feedlots becomes a key factor for alleviating the agricultural non-point source pollution. The shortage of available carbon source for denitrification is the main limiting factor in the bio-treatment of livestock wastewater. The step-fed sequencing batch reactor （SFSBR） is a new type of the enhanced nitrogen removal system, characterized by a multiple anoxic feeding for supplying the organic carbon source to denitrifiers. To facilitate the application of SFSBR in livestock industry, a series of lab-scale experiments were conduced to investigate the performance of SFSBR treating swine wastewater under various operating conditions. The relationship between the pollutants removal efficiency and operating parameters in SFSBR, such as aeration intensity, loading rate, influent carbon nitrogen ratio, feeding volume ratio, was identified in aspects of pollutants evolution, microbial characteristics and on-line process parameters including oxidization reduction potential （ORP）, pH and dissolved oxygen （DO）. As such, an optimal combined operating condition was determined for the SFSBR, together with the profiles of ORP, pH and DO in the reactor. In addition, "the feasibility of sludge granulation in the SFSBR system was explored using swine wastewater as substrates. Main results obtained in this study are as follows:Provided the degradation of organic matter following the first order model, the removal of organic matter in SFSBR is correlated with the reaction time and feeding number. Prolonging the reaction time or multiplying the feeding number would benefit the organic matter removal in the SFSBR system. Given both nitrification and denitrification completed in each sub-cycle of non-aeration-aeration, the theoretical nitrogen removal efficiency is a function of the feeding volume ratio of the last sub-cycle to the total feeding volume （β） and the ratio of initial volume in the tank before feeding to the total feeding volume （V₀/V_F）. The nitrogen removal efficiency of SFSBR would be improved by decreasingβor increasing V₀/V_F. The comparison of A/O-SBR with SFSBR in tank volume shows that the required tank volume of SFSBR is smaller than that of A/O-SBR at the same sludge age.The performance of SFSBR with decreasing feeding volume was influenced by the loading rate, aeration intensity, feeding volume ratio and influent carbon nitrogen ratio. For the twice-fed SBR with decreasing feeding volume, nitrogen removal was inhibited by the increase of organic loading rate （the influent carbon nitrogen ratio varied in random）, while the increase of aeration intensity enhanced the nitrification rate, shortened the nitrification time, and improved the phosphorus removal during the aeration phase. When the feeding volume ratio （greater than 1:1） decreased in the twice-fed SBR, the phosphorus rather than nitrogen removal was significantly improved. In the triple-fed SBR with decreasing feeding volume, both nitrogen and phosphorus removals were inhibited due to the increase in the nitrogen loading rate （the influent carbon nitrogen ratio was fixed）, while those were enhanced by promoting the influent carbon nitrogen ratio. The ORP decreasing range as well as pH decreasing range varied corresponding to the performance of SFSBR under conditions of overloading or enhanced denitrification.Sludge granulation was achieved in SFSBR treating swine wastewater. Granular sludge cultivated in this study is yellow brown and its diameter falls in the range of 0.5 to 1.0 mm, and rich in bacteria species. The loading ratio and influent carbon nitrogen ratio did have significant impacts on the extra-cellular polymers （ECPs） and structure of granular sludge. The results of polymerase chain reaction-denaturing gradient gel electrophoresis （PCR-DGGE） shows that the diversity of bacterial community in activated sludge increased as the influent carbon nitrogen ratio increased.According to the results of orthogonal experiment, the influence order of operating parameters on the performance of SFSBR treating swine wastewater is quite different. The nitrogen loading rate contributed most to the build-up of NO₂^--N, NO₃^--N and NH₄⁺-N in the effluent, while the aeration intensity had the greatest effect on the net nitrogen removal efficiency. The influent carbon nitrogen ratio has a profound influence on the sludge volume index （SVI） and the fraction of granular sludge with a diameter over 0.5 mm (f_0.5mm). In SFSBR, the increase of the feeding volume ratio from 3:2 to 3:1 did not affect the nitrogen removal performance remarkably. The optimal combined operating parameters for nitrogen removal include a carbon to nitrogen ratio of 7mg COD/mg NH₄⁺-N, a feeding volume ratio of 3:1, a nitrogen loading rate of 0.026 gNH₄⁺-N/（gVSS·d）, and an aeration intensity of 4.2 L/（m³·s） in a twice-fed granular sludge sequencing batch reactor treating swine wastewater, at which the net nitrogen removal efficiency has reached 72% with an inorganic nitrogen concentration of 21 mg/L in the effluent. PCR-DGGE results show that optimization of nitrogen removal of SFSBR did have an impact on the bacterial community, and the microflora become less diversified in the granular and mixed sludge, although the bacterial community stay stable in the SFSBR system treating swine wastewater.The variation of ORP, pH and DO has a potential to function as indicators of nitrogen removal in the SFSBR with decreasing feeding volume. The ORP "nitrogen broken point" could indicate termination of nitrification when the initial ammonia nitrogen concentration and aeration time match the aeration intensity. In contrast, the ORP "nitrate knee" could act as an indicator for the termination of denitrification when endogenous denitrification plays an important role in the non-aeration phase. The pH "ammonia valley" also could serve as an indicator for the termination of nitrification, while its sensitivity is interfered with the initial ammonia nitrogen concentration and nitrification time. In addition, both the ORP decreasing range during the non-aeration phase and the pH decreasing range during nitrification have the potential to serve as the control parameter for feeding distribution. In addition, the variation rate of ORP and pH during nitrification could be used to estimate the nitrification rate. As the jump of DO coincides with the termination of nitrification, it could be used to control aeration.The biological phosphorus removal usually happened in the first non-aeraion/aeration sub-cycle of SFSBR in this study, but became insignificant in following sub-cycles. A further study needs to be done to improve the biological phosphorus removal in the SFSBR technique for swine wastewater treatment.更多还原