【作者】 姜涛；

【导师】 吕炳南； 赫俊国；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2011， 博士

【摘要】 磷是水体中藻类和其他光合微生物生长的重要元素,过量的磷能够导致水体富营养化。生物除磷工艺通过系统内富集的聚磷菌实现水中磷的去除,是缓解水体富氧氧化的重要途径。然而由于受环境和操作条件约束力强,生物除磷工艺经常面临运行稳定性差、甚至运行失败的问题,其中无除磷能力而与聚磷菌竞争碳源的聚糖菌的出现与富集是导致除磷效果降低的主要原因。在影响聚糖菌增殖的众多因素中,温度能够决定微生物的稳定性及催化效能,而碳源直接参与聚磷菌和聚糖菌的竞争,因此一直受到广泛关注并存在很多对立观点。基于此,本论文以富集培养的聚磷菌和聚糖菌为研究对象,从厌氧/好氧生化反应过程中代谢化学计量关系和反应动力学的角度深入研究温度和碳源种类对生物除磷系统中聚磷菌和聚糖菌的影响及除磷效能,并在此基础上进行温度和碳源复合因素对聚磷菌和聚糖菌影响的数值模拟计算,为深入理解不同温度及碳源与聚磷菌和聚糖菌的代谢过程、相互竞争、优势地位和除磷效能的关系提供参考。利用常规与逐步限磷方式分别富集了以聚磷菌和聚糖菌为优势菌群的活性污泥系统,荧光原位杂交试验表明聚磷菌富集系统中聚磷菌(Accumulibacter)含量达到86%,而聚糖菌系统中聚糖菌(Competibacter)占78%。通过维持序批式试验温度为5、10、15、20、25和30℃,分别研究了不同温度对聚糖菌和聚磷菌厌氧/好氧反应过程的影响。厌氧序批式试验结果表明温度对聚磷菌厌氧代谢化学计量关系影响不大,与此相反,5和10℃时聚糖菌厌氧ΔPHAAn/ΔVFAAn和ΔGlyAn/ΔVFAAn明显降低,说明低温条件降低了聚糖菌的活性从而抑制了糖原水解能力,需通过其他方式获得能量完成厌氧代谢。温度对聚磷菌与聚糖菌厌氧反应动力学影响显著,聚磷菌和聚糖菌厌氧反应速率分别在20℃和25~30℃达到最高。相同条件下底物最大吸收速率和厌氧ATP维持系数对比结果显示,在温度低于20℃时聚磷菌和聚糖菌对底物的吸收速率差别不大,但聚磷菌自身维持代谢能需求低于聚糖菌,使其在与聚糖菌的代谢竞争中处于优势地位。好氧序批式试验结果表明,温度对聚磷菌好氧反应代谢化学计量关系影响很小,而30℃时聚糖菌好氧化学计量参数降低了约30%,同时温度对聚磷菌和聚糖菌好氧化学反应动力学影响显著。好氧化学反应过程温度系数与国际水协标准温度系数对比表明,聚磷菌和聚糖菌的好氧化学反应与温度属于中等相关关系。在25和30℃时,聚糖菌对底物的吸收速率远高于聚磷菌的吸收速率,但好氧阶段聚糖菌增殖速率始终低于聚磷菌增殖速率。碳源类型对低温生物除磷系统聚糖菌和聚磷菌的影响显著。厌氧底物吸收试验表明,低温条件下聚磷菌厌氧吸收丙酸钠或乙酸钠无选择性,聚磷菌对乙酸钠或丙酸钠的吸收速率基本相同,且丙酸钠能够提高聚磷菌厌氧释磷量,而聚糖菌对丙酸钠的吸收速率仅为乙酸钠吸收量的31%;聚磷菌好氧吸磷试验表明,聚磷菌对好氧PHA组成变化的适应能力的降低导致底物为乙酸钠的聚磷菌好氧吸磷速率高于丙酸钠,主要原因是以丙酸钠为底物时厌氧合成聚羟基烷酸PHA组成成分由PHB转化为PHV和PH2MV。初步研究了碳源对低温反硝化除磷的影响,发现低温生物除磷工艺中含有一定量的的反硝化除磷菌,乙酸钠为碳源时厌氧释磷量与反硝除磷效率较高,但合成的PHA中以PHB为主,降低了反硝化吸磷过程中NO3--N的利用效率;当碳源为混合基质或丙酸钠为碳源时,厌氧释磷量与乙酸钠时接近,但细胞合成的PHA中PH2MV比例逐步增加,能够提高反硝化吸磷过程中NO3--N的利用率。葡萄糖可以作为低温生物除磷的底物,但其启动策略和稳定运行维持方式更为复杂。通过延长厌氧反应时间和系统SRT、降低好氧区DO和反应时间能够实现较为稳定的除磷效果。葡萄糖为碳源时存在厌氧区糖原的合成情况,导致聚磷菌代谢能量来源转移为糖原的后续酵解,从而降低生物除磷系统的稳定性。与乙酸钠为底物时相比,葡萄糖为底物的生物除磷系统厌氧释磷量、PHA合成量均有所降低,厌氧合成PHA的结构由乙酸底物时的PHB为主转化为PHV为主要成分。进行了温度和碳源复合因素对聚糖菌和聚磷菌影响的数值模拟计算,计算结果对生物除磷系统运行状况的预测效果良好;同时不同条件下聚磷菌或聚糖菌生物占有量模拟计算结果表明低温条件下原水碳源为乙酸或丙酸对聚磷菌生物占有量影响不大,低温条件是决定聚磷菌优势地位的主要因素。在中温条件原水碳源为乙酸或乙酸/丙酸混合物时,聚磷菌和聚糖菌共同存在于生物除磷系统内,而碳源为丙酸时为聚磷菌生物占有量达到76%。在高温且原水碳源为乙酸或乙酸/丙酸混合物时,聚糖菌在系统内生物占有量高于聚磷菌,当碳源转化为丙酸时,聚磷菌为系统的优势菌群,聚磷菌和聚糖菌的生物占有量分别为45%和24%。更多还原

【Abstract】 Phosphorus (P) is a key nutrient that stimulates the growth of algae and other photosynthetic microorganisms, and must be removed from wastewater to avoid eutrophication in aquatic water systems. In biological phosphorus removal process(BPR), the phosphorus removal can be achieved by polyphosphate accumulating organisms (PAO) which was accumulated through recirculating sludge from anaerobic and aerobic conditions, and is a vital way to control eutrophication. When operated successfully, the process is a relatively inexpensive and environmentally sustainable option for P removal; however, the stability and reliability, as well as the sensitivity to environment conditions and high operation demanding can be a problem. The enrichment of glycogen accumulating organisms (GAO) who competed with PAO for substrate has been hypothesised to be the cause of the degradation in P removal, and the control of GAO growth is significant for the stability of BPR. Among the factors which influence the growth of GAO, temperature is considered to be the key for the stability and catalytic efficiency of microorganism. Meanwhile, substrates take part in the competition of PAO and GAO directly. From the stoichiometry and kinetics aspect, systemic batch test with enriched PAO and GAO was employed to study the effects of temperature and carbon sources on the metabolism of PAO and GAO. Also the numerical simulation of the operation characteristics under the bybrid effects of temperature and carbon sources was studied. Through the study, the metabolic processes and competition relationship under different temperature and carbon sources could be well understood, and it can be a reference for improving the operation stability under low temperature condition.The enrichment of PAO and GAO could be achieved by traditional and stepwise limiting way, and the fluorescence in situ hybridization(FISH) results showed that the PAO(Accumulibacter) and GAO(Competibacter) content was 86% and 78% respectively. Maintaining the batch test temperature of 5, 10, 15, 20, 25 and 30℃,the effects of temperature on the metabolism of PAO and GAO was investigated. The anaerobic batch test suggested temperature has little influences on the stoichiometry of PAO, but a obvious reduction was observed for GAO in 5 and 10℃, which means a alterative metabolic pathway for GAO to cover the energy. With respect to kinetic process, the temperature has a significant effect on the anaerobic reaction rate. The reaction rate reached the maximum at 20℃and 25～30℃for PAO and GAO, respectively. The uptake rate of PAO and GAO was comparable when the temperature was below 20℃, but the anaerobic ATP maintenance coefficient was lower than that of GAO, which resulted in the superior competition to GAO. In the aerobic batch test, the temperature has a little effects on the aerobic stoichiometry of PAO and GAO, only a reduciton of GAO was found at 30℃. The aerobic kinetic rates increased with the temperature,but medium dependence was found for the aerobic kinetic. Although the growth rate of GAO was always lower than PAO, the competition superior of GAO to PAO was determined by the higher uptake rate above 20℃.The carbon source had a significant influence on PAO and GAO under low temperature. The anaerobic uptake test suggested, PAO had no preferable choice to acetate or propionate, and both the uptake rate was similar. The uptake rate of propionate was only of 31% with that of acetate by GAO by contrast. The adaptable capcity of PAO to PHA compositon was weak which resulted in a lower uptake rate of phosphorus with propionate than that with acetate. The main reason was the differences of PHV and PH2MV synthesized in propionate metabolism to PHB in acetate metabolism. A preliminary test was employed to study the effects of carbon source on denitrifying phosphorus removal. It was found that the low temperature BNR system contained a certain content of denitrifying PAO. The phosphorus release and denitrifying phosphorus removal was higher with acetate as substrate, but the uptake of phosphorus with NO3--N as acceptor was depressed for the component of PHA was PHB. On the other hand, the phosphorus release with compounds and propionate was close to that of acetate, but utilization of NO3--N was improved for the proportion of PH2MV increased.Glucose could be taken as the substrate in low temperature biological phosphorus removal process, but the startup strategy and operation characters were complex. The stability could be implemented by extend the aerobic reaction time and sludge retention time, reduce the aerobic reaction time and dissolved oxygen. The glycogen synthesization was observed in the anaerobic process with glucose as substrate, which caused the energy replaced by the hydrolyzation of glycogen. Compared to the acetate, the phosphorus release and the synthesization PHA was lower, and PHV was the main component in PHA.The competition of PAO/GAO under various temperature and carbon source was evaluated with a incorporated model. The simulation results was well accordance with the operation status. The simulated biomass of PAO and GAO showed that the carbon source on PAO was neglectable under low temperature, and the dominance of PAO was determined by temperature only. Under moderate temperature and acetate or the compounds as substrate, the biomass was composed of PAO and GAO simultaneously. However, the PAO was up to 76% when the sole propionate as substrate. Under high temperature and acetate or the compounds as substrate, the biomass of GAO was higher than PAO. As the substrate was propionate, the biomass of PAO and GAO was 45% and 24% respectively with the PAO as dominance.更多还原