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.     

反硝化除磷系统的启动及其稳定性研究

采用厌氧/缺氧(A/A)SBR为研究对象,通过启动试验研究了反硝化除磷菌(DPB)选择和富集的必要条件.试验结果表明,厌氧/缺氧交替的环境和合适的C、N值可使DPB快速成为系统中的优势菌群;稳定运行后的系统,当进水CODCr∶N∶P为250∶60∶10.5时除磷所用碳源最少,且C、N、P的去除率均在90%以上.当进水CODCr为250 mg/L,SRT为18 d左右,进出水硝氮浓度分别控制在1.5 mg/L和7 mg/L以下时,系统运行稳定性较好.     

不同电子受体的反硝化除磷效果对比研究

反硝化除磷作用可以明显节省脱氮除磷过程的碳源需求和能耗。为研究不同电子受体下的反硝化除磷效果,利用一体化活性污泥工艺中污泥经过厌氧释磷后在不同电子受体下进行反硝化除磷试验,结果表明NO3-—N和NO2-—N均能参与反硝化除磷过程,在NO2-—N初始浓度高达30mg/L的条件下,除磷率仍在93%以上,未对反硝化除磷过程产生毒害作用。在工程应用中应加强短程硝化反硝化与反硝化除磷作用的耦合,在提高脱氮除磷效率的同时,取得明显的节能效果。     

反硝化除磷工艺影响因素研究进展

概述了反硝化除磷工艺原理,介绍了关于碳源、硝酸盐和亚硝酸、温度、pH值、HRT、SRT等影响因素的研究进展,并分析了该反硝化除磷技术的发展前景,建议开展关于反硝化除磷工艺厌氧阶段、以NO3^--N和NO2^--N为电子受体的缺氧阶段各影响因素的多因素正交试验研究。     

污水处理厂反硝化除磷研究及实践

结合苏州娄江污水处理厂生产运行实践,研究了改良型一体化交替反应池在实现良好反硝化除磷条件下的运行工况.实践表明,提高反硝化除磷的关键是要有充足的硝酸盐氮为反硝化聚磷菌(DPB)提供电子受体,当NO-2N浓度在5 mg/L以上时,可以实现较好的反硝化除磷;当SRT为12～14 d时,反硝化除磷和系统脱氮除磷效果最好,生物除磷运行成本较低.此外,进水COD/TP、好氧池DO、厌氧池MLSS以及SRT也是影响一体化反应池生物除磷的主要因素.针对雨季低负荷运行除磷效果不理想的现象,提出了相应的工况运行措施.     

NO-2-N、MLSS对反硝化脱氮除磷的影响

通过对实验室培养的富集反硝化聚磷菌活性污泥在不同电子受体条件、不同MLSS条件下进行缺氧批式试验,研究了NO-2-N作为电子受体时对反硝化脱氮除磷的影响,并与NO-3-N作为电子受体时进行比较。同时分析了MLSS对反硝化脱氮除磷的影响。结果表明:NO-2-N可作为电子受体被DPAOs利用,但是过量的NO-2-N会对吸磷产生抑制作用;NO-2-N作为电子受体可能同时参与了反硝化除磷和常规的内源反硝化。此外,增加活性污泥浓度(MLSS)可提高缺氧吸磷速率,但过高的污泥浓度会导致单位污泥的吸磷速率降低,因此需合理控制反硝化除磷中的MLSS。     

AAO与AO工艺污泥反硝化除磷菌构成研究

反硝化除磷技术因节约碳源、能源而备受关注。以实验室稳定运行的连续流厌氧,缺氧／好氧（AAO）和厌氧／好氧（AO）除磷工艺污泥为研究对象,设计批式试验考察了硝酸盐及亚硝酸盐为电子受体时两种污泥反硝化除磷代谢过程。根据不同电子受体磷去除速率的差异将上述两系统内聚磷菌细分为以氧为唯一电子受体的聚磷菌（Po）,仅以氧、硝氮为电子受体的聚磷菌（PON）和能以氧、硝氮及亚硝氮为电子受体的聚磷菌（PONn）3类,分析结果表明AAO工艺聚磷菌中上述3类功能微生物数量比约为54：16：30．而AOT艺聚磷菌中上述3类功能微生物数量比约为77：3：20。结合聚磷菌划分进一步讨论了不同系统污泥反硝化除磷过程中重要胞内聚合物PHB变化与吸磷量之间的统计关系。     

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。     

溶解氧对低碳源污水一体化处理工艺脱氮除磷的影响

通过试验对比,研究了溶解氧对低碳源污水一体化工艺脱氮除磷效果的影响。结果表明,平均溶解氧为0.18mg/L时,系统出水可以稳定达到GB 18918—2002一级A标准,溶解氧过高或过低都会降低系统脱氮除磷效果。在平均溶解氧为0.18mg/L的工况下,系统存在反硝化吸磷、同时硝化反硝化及全程反硝化3种脱氮方式,且反硝化吸磷和同时硝化反硝化脱氮量占氮总去除量的66.7%,可以较大程度降低脱氮除磷过程所需碳源量并节省耗氧量,提高低碳源污水脱氮除磷效果。     

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。     

Biological phosphorus removal with nitrite as election acceptor.

Biological phosphorus removal was studied in a sequencing batch reactor (SBR). The results showed that nitrite could be used as electron acceptor in denitrifying phosphorus removal. Feed mode of nitrite had significant influence on denitrifying phosphorus removal. Anoxic phosphorus assimilation rate could reach 10.44 mgP/gSS.h and the percentage of anoxic phosphorus assimilation amount was more than 97% with continuous feed mode. Granular sludge with denitrifying phosphorus removal activity was found in the SBR. The effects of different operational conditions, such as COD loading, settling time, HRT etc., on the formation of granules were also studied.     

A two-sludge system for simultaneous biological C, N and P removal via the nitrite pathway

Nitrogen removal via the nitrite pathway results in significant savings in both aeration costs and COD requirements for denitrification when compared to the conventional biological nitrogen removal process. Implementation of the nitrite pathway for simultaneous C/N/P removal in a single sludge system has a major drawback: the aeration phase disfavours denitrifying phosphorus removal. A possible configuration to overcome this issue is the utilisation of a two-sludge system where autotrophic and heterotrophic populations are physically separated. This paper experimentally demonstrates the feasibility of a nitrite-based two-sludge system with sequencing batch reactors (SBR) for the treatment of urban wastewater: a heterotrophic SBR with denitrifying PAOs for P removal and an aerobic SBR for N removal. Partial nitrification was attained in the autotrophic SBR so that shortcut biological nitrogen removal was achieved by using the anoxic dephosphatation activity of DPAOs. Finally, the effect of operating this system without pH control was studied using different influent pH values (pH = 6.8, 7.5 and 8.2) and, despite some efficiency lost due to the pH fluctuations, the system was able to remove most of the C, N and P present in the wastewater.     

A novel wastewater treatment process: simultaneous nitrification, denitrification and phosphorus removal.

Simultaneous nitrification and denitrification (SND) via the nitrite pathway and anaerobic-anoxic enhanced biological phosphorus removal (EBPR) are two processes that can significantly reduce the COD demand for nitrogen and phosphorus removal. The combination of these two processes has the potential of achieving simultaneous nitrogen and phosphorus removal with a minimal requirement for COD. A lab-scale sequencing batch reactor (SBR) was operated in alternating anaerobic-aerobic mode with a low dissolved oxygen concentration (DO, 0.5 mg/L) during the aerobic period, and was demonstrated to accomplish nitrification, denitrification and phosphorus removal. Under anaerobic conditions, COD was taken up and converted to polyhydroxyalkanoates (PHA), accompanied with phosphorus release. In the subsequent aerobic stage, PHA was oxidized and phosphorus was taken up to less than 0.5 mg/L at the end of the cycle. Ammonia was also oxidised during the aerobic period, but without accumulation of nitrite or nitrate in the system, indicating the occurrence of simultaneous nitrification and denitrification. However, off-gas analysis found that the final denitrification product was mainly nitrous oxide (N2O) not N2. Further experimental results demonstrated that nitrogen removal was via nitrite, not nitrate. These experiments also showed that denitrifying glycogen-accumulating organisms rather than denitrifying polyphosphate-accumulating organisms were responsible for the denitrification activity.     

Improvement of denitrification by denitrifying phosphorus removing bacteria using sequentially combined carbon.

The effects of sequentially combined carbon (SCC) using a symbiotic relationship of methanol and acetic acid on biological nutrient removal were investigated in both the continuous bench scale process consisting of an anoxic, an aerobic and a final settling tank and intensive batch tests. Compared to the use of respective sole carbon sources, methanol and acetic acid, the use of SCC showed superior removal efficiency of nitrogen (98.3%) and phosphorus (approximately 100%). Furthermore, the use of SCC enhanced simultaneous denitrification and phosphorus uptake by denitrifying phosphorus removal bacteria (DPB), resulting in the highest specific denitrification rate (SDNR) of 0.252 g NO3-N/g VSS/d achieved from the first anoxic zone with methanol of 30 mg COD/I. From batch tests performed under carbon limited anoxic conditions, 1 g of nitrate was used by DPB for P-uptake of 1.19 g. According to this result, 0.205 g NO3-N/g VSS/d was accomplished by normal denitrifiers using methanol, and 0.047 g NO3-N/g VSS/d was achieved by DPB. This research also demonstrated that the increase of poly-beta-hydroxybutyrate (PHB) stored by phosphorus accumulating organisms (PAOs) could be of importance in improving aerobic denitrification. The use of SCC produced the highest P-release in the anoxic zone, indicating the amount of PHB would be higher compared to the use of other sole carbons. Therefore, the SCC could be a very effective carbon source for the enhancement of aerobic denitrification as well.     

DO对短程同步硝化反硝化除磷工艺的影响

针对碳源偏低的城市污水,采用序批式活性污泥法研究D0对短程同步硝化反硝化除磷工艺的影响,同时对短程同步硝化反硝化和反硝化除磷的机理进行探讨。试验表明：控制DO浓度可在同一个反应器内既实现短程同步硝化反硝化反应又达到反硝化除磷的效果。综合考虑COD、NHg—N、TN、TP的出水浓度达到一级A排放标准,得出最佳的D0控制范围。当D0浓度在0．5～1．0mg／LU时．COD的去除率达到93％～94％,Nil,＋一N的去除率为97％～98％,TN的去除率达到85％一96％,TP的去除率为91％～93％。