低碳城市污水反硝化除磷若干影响因素的试验研究

广州地区城市污水碳量严重偏低、碳氮磷比例失调,其同步脱氮除磷一直是个难题,为此以SBR法进行反硝化除磷影响因素的试验研究.试验表明:缺氧段硝酸盐负荷决定反硝化吸磷效果,在硝酸盐足量情况下,缺氧除磷率达到99.4%.通过对ORP与pH的在线监测发现,ORP无法作为缺氧吸磷过程的控制参数,pH可以指示缺氧吸磷情况.以亚硝酸盐氮作为电子受体研究发现,15 mg/L以下的亚硝酸盐氮可以作为电子受体进行吸磷作用,当亚硝酸盐氮浓度达到23.8 mg/L时,反硝化吸磷受到了明显的抑制;厌氧初始pH在6～8变化时,厌氧释磷量随着pH的升高而增加,pH变化只影响厌氧释磷量,不影响释磷速率.缺氧初始pH降到6时,反硝化吸磷效果变差,缺氧段pH偏碱性条件下,反硝化除磷仍能够稳定进行.     

研究生论文摘要

亚硝酸型硝化的控制与反硝化除磷影响因子的研究研究生:陈鸣岐导师:任南琪(哈尔滨工业大学市政环境工程学院150090)反硝化除磷脱氮双泥工艺(Anaerobic-Anoxic/Nitrification,A2N)是以控制水体富营养化为目的的脱氮除磷新工艺,工艺中包括好氧SBR反应器和厌氧/缺氧SBR反应器。以模拟生活污水为处理对象,分别进行了厌氧/缺氧SBR间歇试验和好氧SBR的连续流试验,为下一阶段运行A2N动态试验提供运行参数的参考范围。在厌氧/缺氧SBR间歇试验中,采用厌氧/缺氧交替运行方式培养驯化反硝化聚磷污泥,结论如下:(1)当厌氧段的pH分别为8、7.5、7…     

硝酸盐浓度及缺氧好氧时段对反硝化聚磷诱导过程的影响

在以厌氧 缺氧 好氧方式运行的SBR反应器中 ,通过改变电子受体———硝酸盐的浓度、缺氧好氧时段 ,研究了反硝化聚磷菌的诱导条件及反硝化聚磷过程的影响因素。试验结果表明 :聚磷菌 (PAOs)包括仅以氧作为电子受体的非脱氮聚磷菌 (non DNPAOs)和既可以氧作为电子受体又可以硝酸盐为电子受体的脱氮聚磷菌 (DNPAOs)。影响脱氮聚磷菌所完成的反硝化聚磷过程的主要因素是电子受体浓度和缺氧好氧时段。     

影响反硝化除磷与厌氧氨氧化耦合的因素

氧对厌氧氨氧化菌有毒,但在颗粒污泥和生物膜中的厌氧氨氧化菌对氧有较高的耐受能力,并且聚磷菌能消耗影响氧氨氧化菌生长的氧。厌氧氨氧化菌的生长无需有机物的参与,聚磷菌释磷需要吸收有机物,少量有机物的加入对厌氧氨氧化菌的活性影响不大。亚硝酸盐是厌氧氨氧化菌氧化氨的电子受体,较高浓度的亚硝酸盐对反硝化聚磷有抑制作用,但合适浓度的亚硝酸盐(该浓度可以通过驯化来提高)可以作为反硝化聚磷菌吸磷的电子受体。厌氧氨氧化过程中有硝酸盐生成,反硝化聚磷菌能利用这部分硝酸盐。另外,两类菌都适宜于中温略偏碱性的环境。因此,通过创造同时对厌氧氨氧化菌和反硝化聚磷菌有利的微生态环境,发挥两者在脱氮除磷方面的协同耦合作用,达到高度脱氮除磷,是极有前景的废水厌氧(缺氧)处理研究方向。     

Do和pH作为SBR硝化终点参数试验研究

为更好地实现SBR脱氮在线模糊控制,以生活污水为研究对象,通过改变曝气量、氨氮负荷等因素,研究DO和pH作为好氧硝化过程终点控制参数的特点。结果表明:曝气量过大时,DO曲线不能明显反映出好氧硝化终点;曝气量在0.16～0.8m~3/h范围内时,SBR好氧硝化阶段出现两次跃升,分别指示异氧菌降解有机底物的结束和自氧菌降解氨氮的终点。pH在7.5～8.2之间,有机物降解至难降解时pH出现极大值,随着硝化反应的进行直至硝化结束,pH不断下降并出现极小值,然后pH快速上升或维持不变。     

不同温度下反硝化除磷工艺ORP变化规律研究

采用SBR反应器分别研究了低温（15℃和13℃）与常温（25℃）条件下反硝化除磷工艺ORP变化规律。研究结果表明：混合液ORP在厌氧、缺氧及好氧阶段的变化与温度有关，但厌氧阶段水力停留时间在2h以上时，初始厌氧程度对DPB的厌氧释磷过程基本无影响。     

好氧颗粒污泥低温反硝化除磷的影响因素研究

以模拟城市生活污水为原水,在低温条件下研究SBAR反应器中好氧颗粒污泥反硝化除磷的效能。采用多组平行试验考察了pH、NO_3~-—N、NO_2~-—N、碳源类型对反硝化除磷的影响。结果表明:用乙酸钠作为碳源,pH控制在7±0.1,初始硝酸盐浓度为5 mg/L,或初始亚硝酸盐控制在15～30 mg/L时,有较理想的脱氮除磷效果。     

采用两级SBR工艺优化除磷脱氮

在充分分析单级SBR工艺在生物除磷脱氮过程中存在的不足的基础上 ,提出了两种两级SBR串联运行的除磷脱氮工艺模式。通过合理控制操作过程 ,该工艺可望从根本上解决单级生物除磷脱氮系统中的泥龄问题、厌氧区的硝酸盐问题、有机物对硝化作用的抑制问题和好氧时间长能耗较高的问题等 ,从而可大大提高系统除磷脱氮效果和稳定性。模式 1工艺适用于处理BOD/TP值较高的污水 ;模式 2工艺对进水BOD/TP值没有特殊的限制。     

基于短程反硝化和厌氧氨氧化的城镇污水处理新工艺

厌氧氨氧化（ANAMMox）是迄今为止最具有可持续性的污水脱氮途径。但厌氧氨氧化用于城镇污水时却遭遇到亚硝酸盐难以获取的困境。为此提出将反硝化进行到一半,积累亚硝酸盐作为厌氧氨氧化反应电子受体。据此提出了以短程反硝化和厌氧氨氧化联用为核心的城镇污水脱氮除磷新工艺。对该工艺的可行性进行了分析并提出了今后的研究方向。     

连续流活性污泥法实现城镇污水短程脱氮的影响因素分析

城镇污水短程脱氮工艺关键技术之一是如何将氨氧化控制在亚硝化阶段。综合分析温度、pH、DO浓度、进水C/N比、进水方式、缺氧/好氧区体积比、污泥丝状菌膨胀、SRT、HRT、氨氮负荷、污泥浓度、内回流比、化学抑制剂等因素对污水短程硝化过程的影响作用,为常温连续流条件下实现城镇污水的短程脱氮提供技术参考。     

Monitoring pH and ORP in a SHARON reactor

This paper analyses the valuable information provided by the on-line measurements of pH and oxidation reduction potential (ORP) in a continuous single high ammonia removal over nitrite (SHARON) reactor. A laboratory-scale SHARON reactor equipped with pH, ORP, electric conductivity and dissolved oxygen (DO) probes has been operated for more than one year. Nitrogen removal over nitrite has been achieved by adding methanol at the beginning of anoxic stages. Time evolution of pH and ORP along each cycle allows identifying the decrease in nitritation rate when ammonia is consumed during the aerobic phase and the end of the denitrification process during the anoxic phase. Therefore, monitoring pH and ORP can be used to develop a real-time control system aimed at optimizing the length of both aerobic and anoxic stages. Real-time control of methanol addition can be carried out by using the information provided by these probes: excessive methanol addition in the anoxic stage is clearly detected in the ORP profile of the following aerobic phase, while a deficit of methanol is detected in both pH and ORP profiles of that anoxic phase. Moreover, other valuable information such as the amount of ammonia nitrified, failures in DO measurements, excessive stirring during the anoxic stage and methanol dosage in the aerobic phase was also provided by the pH and ORP profiles.     

Feasibility of controlling nitrification in predenitrification plants using DO, pH and ORP sensors.

Experimental studies were carried out on a bench-scale nitrogen removal system with a predenitrification configuration to gain insights into the spatial and temporal variations of DO, pH and ORP in such systems. It is demonstrated that these signals correlate strongly with the operational states of the system, and could therefore be used as system performance indicators. The DO concentration in the first aerobic zone, when receiving constant aeration, and the net pH change between the last and first aerobic zones display strong correlations with the influent ammonia concentration for the domestic wastewater used in this study. The pH profile along the aerobic zones gives good indication on the extent of nitrification. The experimental results also showed a good correlation between ORP values in the last aerobic zone and effluent ammonia and nitrate concentrations, provided that DO in this zone is controlled at a constant level. These results suggest that the DO, pH and ORP sensors could potentially be used as alternatives to the on-line nutrient sensors for the control of continuous systems. An idea of using a fuzzy inference system to make an integrated use of these signals for on-line aeration control is presented and demonstrated on the bench-scale system with promising results. The use of these sensors has to date only been demonstrated in intermittent systems, such as sequencing batch reactor systems.     

Influence of ORP variation, carbon source and nitrate concentration on denitrifying phosphorus removal by DPB sludge from dephanox process.

The effect of added carbon source and nitrate concentration on the denitrifying phosphorus removal by denitrifying phosphorus removal bacteria sludge was systematically studied using batch experiments, at the same time the variation of ORP was investigated. Results showed that the denitrifying and phosphorus uptake rate in the anoxic phase increased with the high initial anaerobic carbon source addition. However, once the initial COD concentration reached a certain level, which was in excess of the PHB saturation of Poly-p bacteria, residual COD carried over to the anoxic phase inhibited the subsequent denitrifying phosphorus uptake. This was equal to supplementing the external carbon source to the anoxic phase, furthermore the higher the external carbon source concentration the more powerful the inhibition caused. High nitrate concentration in the anoxic phase increased the initial denitrifying phosphorus rate. Oncethe nitrate was exhausted, phosphate uptake changed to phosphate release. Moreover, the time of this turning point occurred later with the higher nitrate addition. On the other hand, through on-line monitoring the variation of the ORP with different initial COD concentration, it was found that ORP could be used as a control parameter for phosphorus release, but it is impossible to utilize ORP for controlling the dinitrification and anoxic phosphorus uptake operations.     

Automatic control strategy for biological nitrogen removal of low C/N wastewater in a sequencing batch reactor.

To establish an automatic control system of external carbon addition in biological nitrogen removal, a bench-scale sequencing batch reactor with real-time control strategy was designed in this study. An oxidation-reduction potential (ORP) profile was used for automatic control of external carbon addition. The mean removal efficiency of total organic carbon was over 98%. Complete denitrification in an anoxic phase and complete denitrification and nitrification in anoxic and oxic phases were accomplished, respectively, because the oxic and anoxic periods were also appropriately controlled with ORP and pH profiles, respectively. Mean removal efficiency of total nitrogen was over 95%. When concentration of influent wastewater was changed, volume of additional carbon was automatically changed with the influent fluctuation, and flexible hydraulic retention time was achieved in this system.     

Full-cyclic control strategy of SBR for nitrogen removal in strong wastewater using common sensors.

A full-cyclic automatic control strategy for sequencing batch reactors (SBR) was proposed using only common sensors such as ORP, DO and pH. The main objective was to develop a generally applicable and robust control strategy. To accomplish this, various control schemes found in the literature or suggested by authors were examined at diverse ammonia loads and SCOD/NH4(+)-N ratios. Advantages and constraints of each scheme were discussed and compared. Ammonia load was estimated with DO lag time during the aerobic stage, and then the influent pump was manipulated to meet the desired load at the next anoxic stage. A partial denitrification scheme was chosen for the anoxic stage period control, to save anoxic time and external carbon. For external carbon dosage control, intermittent feeding at each anoxic stage was concluded to be a suitable scheme. The anoxic stage period could be successfully controlled by the combination of pH increase and DO increase. Every suggested control scheme was incorporated into a full-cyclic control strategy and tested at 0.02, 0.035, 0.08 kg NH4(+)-N/m3/sub-cycle. From the results, it is expected to perform unmanned automatic SBR operation with this strategy.     

Nitrogen removal from pharmaceutical manufacturing wastewater via nitrite and the process optimization with on-line control.

In this study, laboratory scale experiments were conducted to investigate the nitrogen removal from pharmaceutical manufacturing wastewater. The results indicate that by selective inhibition of free ammonia on oxidizers, nitrogen removal can be achieved by nitritation and denitritation process. The nitrite ratio was above 98% in the aerobic stage and the nitrogen removal efficiency was about 99%. The complete ammonia removal corresponded exactly to the "Ammonia Valley" in the pH versus time graphic and the anoxic reaction was completed when the "Nitrite Knee" appeared in the ORP versus time graphic. Optimization of the SBR cycle by step-feed and on-line control with pH and ORP strategy allowed the carbon and energy saving. The easy operation and the low cost make the SBR system an interesting option for the biological nitrogen removal from the pharmaceutical manufacturing wastewater.     

In-situ characterization of microbial community in an A/O submerged membrane bioreactor with nitrogen removal.

The bacterial community involved in removing nitrogen from sewage and their preferred DO environment within an anoxic/oxic membrane bioreactor (A/O MBR) was investigated. A continuously operated laboratory-scale A/O MBR was maintained for 360 d. At a sludge age of 150 d and a C/N ratio of 3.5, the system was capable of removing 88% of the influent nitrogen from raw wastewater through typical nitrogen removal transformations (i.e. aerobic ammonia oxidation and anoxic nitrate reduction). Characterization of the A/O MBR bacterial community was carried out using fluorescence in situ hybridization (FISH) techniques. FISH results further showed that Nitrosospira spp. and Nitrospira spp. were the predominant groups of ammonia and nitrite oxidizing group, respectively. They constituted up to 11% and 6% of eubacteria at DO below 0.05 mg/l (low DO), respectively, and about 14% and 9% of eubacteria at DO between 2-5 mg/l (sufficient DO), respectively, indicating preference of nitrifiers for a higher DO environment. Generally low counts of the genus Paracoccus were detected while negative results were observed for Paracoccus denitrificans, Alcaligenes spp, and Pseudomonas stutzeri under the low and sufficient DO environments. The overall results indicate that Nitrosospira spp., Nitrospira spp. and members of Paracoccus spp. can be metabolically functional in nitrogen removal in the laboratory-scale A/O MBR system.     

骆马湖水质对菹草不同生长期的响应研究

采用原位观测手段研究了骆马湖菹草生长区水质与菹草不同生长期的响应关系。结果表明:指数生长期和石芽生成期,水体中的pH值、ORP值和DO质量浓度升高,COD质量浓度降低;植株衰亡期则相反,菹草腐烂导致有草区的水体TP质量浓度升高,但是由于反硝化作用,水体中TN与硝氮质量浓度反而下降。菹草在生长过程中直接吸收水体中的硝氮,对氨氮的去除则为间接作用,此时水体中的氮以硝氮为主;当菹草衰亡时,氨氮成为水体中氮的主要存在形态。菹草密度是影响水体各形态氮浓度的重要因素,在菹草生长时,菹草密度与TN和硝氮质量浓度显著负相关(P 0.01);当菹草衰亡时,与菹草稀疏区相比,菹草密集区TN和硝氮质量浓度更低,而氨氮质量浓度更高。指数生长期,骆马湖最优菹草密度为83.75 g/m~3。     

Some observations on the effects of accumulated benthic sludge on the behaviour of waste stabilisation ponds.

The effect of accumulated bottom sludge on water column characteristics was studied in two pilot-scale ponds. Parameters measured were ammonia, nitrate, phosphate, COD, suspended solids, dissolved oxygen (DO), temperature and light intensity. The de-sludged pond showed a stronger correlation between DO, light intensity, nutrients and suspended solids with the controlling factor being availability of nitrogen. This was less apparent in the pond with sludge where nutrient levels were higher and more complex mechanisms controlled biomass concentration. Water column characteristics in the two ponds converged rapidly in 7-10 weeks, however, due to accumulation of fresh sludge.