【作者】 金羽；

【导师】 任南琪； 李建政；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2013， 博士

【摘要】 城镇污水排放始终是地表水的主要污染源，对其进行有效处理是保护水环境的重要措施。在北方寒冷季节，污水处理系统的效能也会因微生物代谢水平下降而受到显著影响，主要污染物，尤其是氮磷的达标排放受到严重威胁。为解决北方污水处理设施在寒冷季节处理效能低，出水达标保障率大幅下降的问题，开发低温污水强化处理技术意义重大。本论文以具有良好脱氮除磷功能的厌氧-缺氧-好氧（A²/O）污水处理系统的运行为基础，对比了23℃和14℃条件下A²/O系统的处理效能，探讨了季节性水温变化对系统处理效能的影响规律和生物学机制，并进一步研究了14℃条件下A²/O系统脱氮除磷效能的强化技术，以期为工程技术的应用提供理论指导和技术支持。A²/O系统在水温为23℃和14℃条件下的启动运行结果表明，温度降低显著延长了A²/O系统的启动过程，且降低了系统的处理效能。在HRT10h、MLSS2800～3000mg/L、好氧池DO2～3mg/L、二沉池污泥回流比50%、硝化液回流比200%和SRT15d的条件下，23℃运行的A²/O污水处理系统可在24d内启动成功并达到稳定运行状态，而在14℃条件下运行的系统，其启动过程则需要28d。当系统处于稳定运行时，23℃和14℃的系统均能保持87%和92%以上的COD和TP去除率，能够满足《城镇污水处理厂污染物排放标准》（GB18918-2002）一级A标准的要求。但在14℃条件下，即便通过污泥回流比和硝化液回流比的优化，系统出水NH₄⁺-N和TN仍不能满足排放要求。对于北方寒冷季节的A²/O污水处理系统的运行管理，应重点关注对NH₄⁺-N氧化能力的调控。温度的季节性降低对A²/O系统的处理效能具有显著影响。在水温从23℃阶段性降为18℃、14℃和11℃的过程中，A²/O系统对污染物的去除效能总体表现为下降趋势。但是，即便是在11℃的条件下，系统出水COD和TP仍能满足GB18918-2002一级A标准。而温度降低到14℃以下时，系统对NH₄⁺-N和TN的去除效能明显下降，甚至无法达标排放。对系统活性污泥微生物的检测发现，活性污泥微生物群落随着季节性温度变化发生了演替，在特定温度下均能检测到新的优势菌群的出现。尽管温度下降从整体上降低了活性污泥的代谢能力，但新的优势菌群的出现，从一定程度上弥补了活性污泥在低温条件下代谢能力的不足，使系统在14℃¹8℃的较低温度下仍能表现出良好的污染物去除效能。然而，这一“补偿作用”是有一定限度的，当水温降低到14℃以下时，尽管也有新的耐冷菌群出现，但系统的整体处理效能仍然受到了很大限制，尤其是增殖缓慢的硝化细菌和反硝化细菌，当温度下降时，其代谢能力受到严重影响，造成系统出水NH₄⁺-N和TN无法达标。驯化培养耐冷功能菌群并以其对A²/O系统进行生物强化，是提高低温条件下污水处理效能的有效途径。以3.24%（w/w）的比例向14℃运行A²/O系统投加耐冷硝化功能菌群，可使系统的NH₄⁺-N和TN去除率从强化前的65%和59.4%提高到72.8%和67.2%，COD去除率也由88%提高到了91%。可见，耐冷硝化功能菌群的投加，不仅提高了系统的脱氮效率，同时也提高了COD去除能力。根据生物脱氮除磷的基本原理，设计出具有厌氧（包括缺氧）和好氧生物相分离功能的双污泥旁路A²/O改良工艺，中间沉淀池和厌氧释磷池的增设，显著提高了A²/O系统的脱氮除磷效能。在HRT10h、中间沉淀池污泥回流比50%、好氧污泥厌氧释磷12h、厌氧释磷池污泥回流比控制在75%等优化条件下，改良A²/O系统在14℃运行时，其出水COD、NH₄⁺-N、TN及TP平均浓度分别为20mg/L、7.8mg/L、18.9mg/L和0.3mg/L。其中，COD和TP达到了GB18918-2002一级A标准，而NH₄⁺-N和TN也达到了一级B标准。更多还原

【Abstract】 Urban sewage discharge is always the main source of pollution in cities andtowns, therefore, to deal effectively with it is the important measures to protect thewater environment. The biological sewage treatment effectiveness is significantlyaffected by the decreased microbial metabolism in north cold seasons, the majorpollutants-nitrogen and phosphorus discharge in particular is threatened. Theexisting sewage treatment facilities are almost ineffective during the cold season inthe North, sewage effluent quality is worse accordingly, and consequently, it is verysignificant to develop low-temperature sewage enhanced processing technology. Inthis study, based on the operation of a lab-scale A²/O sewage treatment process, theperformance characteristics under23℃and14℃conditions were investigated. Atthe same time, the effect of seasonal temperature variation on A²/O process systemeffectiveness and microbial mechanisms was analyzed. Moreover, the enhancementof nitrogen and phosphorus in A²/O process system at14℃has been researched,with a view to provide theory guidance and technology support for engineeringtechnology application.The A²/O reactor was started up and after reaching stable state at HRT10h,MLSS2800³000mg/L, DO2³mg/L, sludge return ratio50%, nitrification liquidreturn ratio200%and SRT15d conditions, the results showed that low temperaturenot only slowed down the startup process but also decreased sewage treatmentefficiency with time. The A²/O system with a temperature of23℃reached its stablestate earlier than the lower temperature system, which was operated at a temperatureof14℃. The COD and TP concentration in effluent of the A²/O systems stablyoperated both23℃and14℃could meet the First Grade （A） of the ChineseNational Discharge Standard of Pollutants for Municipal Wastewater （GB18918-2002）, with a removal rate of87%and92%, respectively. In addition, undertemperature of14℃, even the sludge return ratio and nitrification liquid return ratiowas optimized, NH₄⁺-N and TN concentration in effluent meet only the First GradeB. In future, the regulation and control of A²/O sewage treatment process in coldweather should focus on the enhancement of ammonia oxidization.The seasonal change of temperature in north China has significant impact onthe performance of A²/O process system. The efficiency of A²/O process system wasoverall downward following the temperature drop from23℃to18℃,14℃and11℃,step by step. However, even at the temperature of11℃, the TP and COD concentration in effluent still meet the First Grade A, but when temperature wasbelow14℃, the NH₄⁺-N and TN removal efficiency dropped significantly, unable tomeet the First Grade A. The activated sludge microbial community structurechanged with the seasonal temperature variation. The new groups of dominantbacteria were able to be detected under specific temperatures. Despite the decline intemperature reduced the metabolism of activated sludge, but the emergence of anew group of dominant bacteria, from a certain extent, make up for the insufficientmetabolism of activated sludge under low temperature conditions. So, the systemstill demonstrated better removal efficiency of pollutants when the watertemperature at14℃¹8℃. However, this―compensation‖was a certain limit, whenthe water temperatures was below14℃, although there were new cold-resistantbacteria emerged, but the effectiveness of A²/O process system was still subject toconsiderable restrictions. In particular, the metabolic and proliferative capacities ofnitrifying&denitrifying bacteria have been severely affected in low temperatureconditions.It is an effective measure to enhance A²/O system efficiency operated underlower temperature by augmenting with cold-adapted functional flora. When thecold-adapted ammonia-oxidizing functional flora was put into the oxic tanks of theA²/O process with a mass ratio of3.24%（w/w）, the average NH₄⁺-N and TNremoval increased from65%and59.4%to72.8%and67.2%, respectively. TheCOD removal also increased from88%to91%. Obviously, the cold-adaptedammonia-oxidizing functional flora not only enhanced the system nitrogen removalefficiency, simultaneously sharpened the COD removal ability.According to the basic principle of biological nitrogen and phosphorus removal,an anaerobic （including anoxic） and oxic bio-separation function of two-sludgebypass A²/O improvement process was designed. Therefore, the conflicts onbiological nitrogen and phosphorus removal in metabolic rate and carbon sourcecompetition aspects were solved. The performance of improved A²/O system hasbeen significantly enhanced by setting the middle sedimentation tank and the sludgeanaerobic phosphorus release tank. When the improved A²/O system operated stablyat HRT10h, middle sedimentation tank sludge return ratio50%, anaerobic releasephosphorus tank SRT12h, phosphorus release tank sludge return ratio75%, and attemperature of14℃conditions, the effluent COD, NH₄⁺-N, TN and TPconcentration were20mg/L,7.76mg/L,18.9mg/L and0.28mg/L, respectively.The COD and TP concentration in effluent meet the First Grade A, the NH₄⁺-N andTN concentration in effluent meet the First Grade B.更多还原