【作者】 韩玮；

【导师】 袁林江；

【作者基本信息】 西安建筑科技大学 ， 环境工程， 2015， 博士

【摘要】 强化生物除磷技术(Enhanced Biological Phosphorus Removal,简称EBPR)以其经济性突出而在城市污水处理中得到了广泛的应用。但生物除磷效果常常波动较大,往往造成城市污水处理厂出水磷浓度不易达标。因此,如何保证污水生物除磷的稳定性、进一步提高除磷效率是目前工程实践中有待解决的一个课题。由于人们对生物除磷机理认识还不透彻,对影响生物除磷效率的内外环境因素也并不完全掌握,因此往往在设计和工程运行调控上都存在一定的盲目性,难以确保生物除磷系统的稳定与高效运行。本课题通过控制进水方式、改变磷酸盐浓度与污泥龄等外在条件,在SBR生物除磷系统中对污水COD与污泥中聚-β-羟基链烷酸酯(Poly-β-hydroxyalkanoate,简称PHA)之间的转化规律,以及PHA与生物聚磷效能之间的关系进行了研究,旨在通过试验揭示影响生物除磷效率的内在因素和生物除磷的机制,为提高生物除磷系统的可控性提供理论依据。采用模拟生活污水,分别对以厌氧/好氧(A/O)、厌氧/缺氧/好氧(A/A/O)和厌氧/缺氧(A/A)方式运行的实验室规模SBR生物除磷系统的运行结果进行了检测,研究了不同进水方式、磷酸盐浓度、污泥龄对生物合成PHA以及生物除磷效率的影响。研究结果表明:(1)采用进水不投加磷酸盐,缺氧投加磷酸盐的进水方式有利于A/A-SBR反硝化除磷系统的启动。(2)污泥龄能够改变聚磷菌胞内PHA的物质组成。延长污泥龄能够提高外碳源利用率,提高污泥中的PHA含量,提高PHV在PHA中所占的比例,并缩短聚磷所必须的好氧时间。当污泥龄分别为12d和20d时,外碳源利用率分别达到34%和74%。当污泥龄为12d、20d和48d时,污泥中PHA合成量分别达到26.9mgPHA/gVSS、51.9mgPHA/gVSS和73.9 mgPHA/gVSS;PHV占PHA的比例分别为31%、58%和68%;水中磷酸盐浓度达到0.5mg/L所需的好氧反应时间分别为60min、45min和30min。(3)胞外聚合物(Extracellular Polymeric Substances,简称EPS)具有一定的储磷能力,不同的生物除磷工艺其胞外聚合物的除磷能力大小不同。在A/O-SBR除磷系统中,胞外聚合物含磷量呈现周期变化,在反应结束时恢复到初期的水平。活性污泥中的磷在细胞内和胞外聚合物中的分配比例会随污泥龄的变化而变化。当污泥龄为12d时污泥中的磷有40%储存于胞外聚合物中,而污泥龄达到20d以上时,污泥中的磷仅有20%储存于胞外聚合物中,其余的80%被细胞吸收。论文认为:(1)正是由于除磷机制不同,对于A/A-SBR反硝化除磷系统,以二次进水方式向除磷系统中投加含磷废水有利于系统的启动和长期稳定运行。(2)污泥PHA消耗量与污泥吸磷量之间并非线性相关关系。对于进水COD浓度约为450mg/L的A/O-SBR除磷系统,每消耗1gPHA能够吸收的磷酸盐最多可达0.88g,活性污泥吸磷量最大可达0.45mgP/mgVSS。当磷负荷过高时,通过调节厌氧时间能够提高系统的除磷率。(3)延长污泥龄能够提高聚磷菌对外碳源的利用率,提高污泥中PHA含量,并提高PHV在PHA中所占的比例。长泥龄下的A/O-SBR除磷系统不仅能够稳定运行,而且能够减少剩余污泥产量。(4)胞外聚合物含磷量多少由不同的除磷工艺和运行条件来决定。胞外聚合物在生物除磷中的作用主要是调节厌氧释磷和好氧吸磷时的细胞膜外磷酸盐浓度,缓和液相高磷负荷对聚磷菌的不利影响等辅助作用。通过调节污泥龄能够改变磷在细胞内和胞外聚合物中的比例。更多还原

【Abstract】 Enhanced biological phosphorus removal(EBPR) technology had been widely used in municipal wastewater treatment due to its outstanding economic advantage. But the phosphorus effluent concentration of effluent of urban sewage treatment plant was not easy up to the standard because biological phosphorus removal performance was not stable. The problem was to solve engineering practice were the stability and the high efficiency of biological phosphorus removal. Design and engineering operating regulation had some blindness because phosphorus removal mechanisms and the impact factors were unclear. It was difficult to ensure a stable and efficient operation of biological phosphorus removal system because of blindness design.By changing the operation and ambient conditions(feeding mode, concentration of phosphorus and sludge retention time etc.), this thesis studied the relationship of COD and intracellular poly-β-hydroxyalkanoate(PHA) and studied the relationship of PHA and biological phosphorus removal. The purpose of the study was to reveal effects of ambient factors on biological phosphorus removal and PAOs’ responding mechanism so that managers could improve control ability of biological phosphorus removal in engineering practices.The synthetic wastewater was used to study the phosphorus removes in A/O-SBR( anaerobic/aerobic-SBR),A/A/O-SBR( anaerobic/anoxic/aerobic-SBR) and A/A-SBR(anaerobic/anoxic-SBR) systems. This paper discussed the effects of phosphorus feeding modes, phosphorus concentration and sludge retention time on PHA’s synthesis and biological phosphorus removal efficiency as well as their responding mechanisms.The results obtained from the study are shown as follows.(1)Feeding mode of anaerobic no phosphorus and anoxic phosphorus helps A/A-SBR to start.(2)Sludge retention time can change PAOs’ intracellular PHA composition. Prolonged sludge retention time can improve the utilization rate of external carbon source, increase the content of PHA, improve proportion of PHV in PHA, and shorten the essential aerobic time of uptaking phosphorus. When the sludge retention time was respectively 12 d and 20 d, external carbon source utilization rate reached 34% and 74%. When the sludge retention time was 12 d, 20 d and 48 d, PHA synthesis in the sludge were respectively 26.9mg PHA/g VSS, 51.9mg PHA/g VSS and 73.9 mg PHA/g VSS; and the proportion of PHV in PHA were respectively 31%, 58% and 68%; and respectively aerobic 60 min, 45 min and 30 min phosphorus concentration reached 0.5mg/L.(3)Extracellular polymeric substances(EPS)saves a certain amount of phosphorus. Different processes have different EPS phosphorus removal abilities. In A/O-SBR phosphorus removal system, extracellular polymeric phosphorus presents periodic variation. At the end of the reaction, EPS phosphorus recovers to the initial levels. Sludge retention time can be the distribution rates of phosphorus changing in intracellular and extracellular polymeric substances of activited sludge. When the sludge retention time of 12 days, the 40% of all stored in the sludge phosphorus exists in EPS. When the sludge retention time of 20 days, only 20% of all stored in the sludge phosphorus exists in EPS, and the remaining 80% exists in intracellular.The following conclusions obtained by experiment:(1)Because of different phosphorus removal mechanism, feeding mode of anaerobic no phosphorus and anoxic phosphorus helps A/A-SBR to start and stable operation.(2)PHA consumption and sludge phosphorus uptaking is nonlinear correlation. If COD of influent is 450mg/L, consumpting each gram PHA activated sludge can absorb phosphate up to 0.88 grams, and each gram activated sludge can uptake phosphate up to 0.45 grams. When the phosphorus load is too high, by adjusting the anaerobic time can improve the biological phosphorus removal efficency.(3)Prolong sludge retention time can improve the utilization of external carbon source rate, increase the content of PHA in the sludge, and increase proportion of PHV in PHA. longer sludge retention time A/O-SBR phosphorus removal system not only can run stably, but also reduces the production of excess sludge.(4)Different biological phosphorus removal systems because of different operating conditions have different extracellular polymeric substances phosphorus contents. Extracellular polymeric substances phosphorus removal is secondary. Its main function is to mitigate the impact of high phosphorus load in water and to regulate the phosphate concentration of the outside of the cell membrance at the time of anaerobic phosphorus releasing and aerobic phosphorus uptaking. Sludge retention time can be the distribution rates of phosphorus changing in intracellular and extracellular polymeric substances of activited sludge.更多还原