天然水体氮自净过程及硝化所需溶解氧源试验验证

通过试验验证了天然水体中确实存在氮的自然净化过程和同步硝化/反硝化途径。在氮与有机物浓度较低时,遮光阻断藻类光合作用试验表明,大气复氧足以使试验水质条件下的氮和有机物完全氧化。然而,有机物过早消耗对硝化后产生的硝酸氮再行反硝化作用不利。反硝化反应彻底进行可以通过外加碳源方式实现。COD初始浓度较高会引起异养菌对氧的大量消耗,使本来数量就处于劣势的硝化细菌的硝化反应受阻。     

沸石床复合垂直流人工湿地脱氮机理分析

通过研究沸石床复合垂直流人工湿地中不同形态氮的空间变化,分析了其脱氮机理,认为沸石对NH_3—N的吸附作用是脱氮的重要途径,硝化和反硝化作用提高了TN的去除率,硝化和反硝化强度影响到沸石的饱和周期和生物再生,有待进一步研究。     

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。     

潜流湿地短程硝化反硝化强化脱氮研究

为探索人工湿地系统短程硝化反硝化脱氮作用对微污染水体脱氮性能的提升效果及影响因素,构建两级垂直流潜流湿地系统,对比分析了间歇进水、同步回流、预曝气等运行方式下的净水效果及含氮污染物的转化规律,结果表明:进水低碳氮比条件下,系统对COD_Cr和NH■-N的去除率稳定在60.5%～64.3%和90%以上;通过水位/水量调节方式强化湿地内部自然富氧作用,实现TN去除效果增长8%～10%,亚硝化率呈升高趋势,NO■-N的累积现象有所改善;氨氧化细菌（AOB）和氨氧化古菌（AOA）群落分布一致性和优势群菌丰度显著提升,反硝化细菌（nirS）优势种群分布同时得到改善,水位/水量调控的运行方式可以提升短程硝化效率,为反硝化反应提供更充足的底质和溶解氧条件,强化湿地系统对微污染水体的短程硝化反硝化脱氮作用。     

镇江市金山湖水质强化净化与生态修复关键技术

项目主要完成了以下内容: (1)研发了生态漂浮床技术、仿生植物技术以及固定化微生物技术等,获得生态浮床植株种植密度、植物不同收割频次下,生态浮床对水质的净化效能;获得仿生植物对水体微生境的影响及其对主要污染物的降解效能. (2)筛选了纯化金山湖沉积物中3种氮循环功能微生物(氨氧化细菌、硝化细菌、好氧反硝化细菌),获得了包埋法制成固定化小球的最佳反应条件等关键参数.(3)研究了生物扰动下沉积物对氮磷元素的释放速率,揭示了生物扰动对氮磷元素的影响. (4)构建了3种单一系统:生态浮床系统、仿生植物系统、固定化微生物系统,以及组合而成的复合系统和对照系统,获得各实验系统对水体氮素去除效能的变化数据. (5)通过野外实验,研究了复合生态系统的性能.     

镉对污水生物脱氮反应动力学的影响研究

通过批量试验检测COD、NH+4-N和NOx-N的去除率和比降解速率,研究了Cd2+对活性污泥生物脱氮反应动力学的影响。结果表明:在硝化反应和反硝化反应有机物降解过程中,5 mg/L的Cd2+即会对有机物的去除率产生抑制作用,20 mg/L的Cd2+对有机物去除率和有机物比降解速率有显著抑制效应;在硝化反应NH+4-N的去除过程中,20mg/L的Cd2+会显著抑制对NH+4-N的去除,10 mg/L的Cd2+可造成比硝化速率的显著降低;在反硝化反应NOx-N的去除过程中,Cd2+对NOx-N去除率没有显著影响,20 mg/L的Cd2+对比反硝化速率有显著抑制效应。     

三种反硝化工艺比较

颗粒滤床、悬浮活性污泥法和弹性填料生物膜法三种反硝化工艺有机物容积去除负荷均在 2kgCOD/ (m3·d)以上。通过过程稳定性、反硝化程度及反应动力学速率常数比较分析 ,颗粒滤床与悬浮活性污泥法优于弹性填料生物膜法 ,颗粒滤床反硝化更适合给水处理 ,悬浮活性污泥法反硝化容易在废水处理中运用     

焦化废水反硝化段生态环境中细菌含量及菌相的研究

以《伯杰氏系统细菌学手册》第1、2卷及《一般细菌常用鉴定方法》等为主要依据,对上海焦化总厂焦化废水反硝化段的试样进行了细菌数量及菌相分析研究,并对反硝化细菌在反硝化段生态环境中的分布进行了探讨.结果表明,反硝化段废水含菌量为1×10~7个/mL,     

短程硝化反硝化生物脱氮技术的影响因素及工程应用

应用短程硝化反硝化反应处理氮肥企业排放的低碳氮比污水在经济上和技术上具有很大的应用价值。然而,诸多影响因素对这一反应的最终效果影响很大。通过查阅文献资料,总结了影响微生物短程硝化反硝化生命活动的主要因素;同时结合近期有关这一理论的工程应用情况,整理了不同短程硝化反硝化反应的工程实践结果,分析得到:亚硝化细菌在20℃时比生长速率最大,且随温度的升高而降低;反应的理想pH值应大于8.5;低DO条件下亚硝酸盐更容易得到积累。通过在工程上间接调整影响因素,可以有效控制微生物的反应类型,减少曝气量,节约运行成本。因此,讨论短程硝化反硝化反应的影响因素有利于深入开发具有较强适应性的污水处理工艺;同时,总结不同关于短程硝化反硝化反应的工程实践结果有利于更多工程应用的开发,解决更多高难废水的处理问题。     

不同碳源及投量对SBR法反硝化速率的影响

以啤酒废水为试验研究对象 ,主要对SBR法去除有机物、硝化和反硝化进程进行了分析 ,并且系统地研究了啤酒原水以及不同原水投加量、不同投加方式 ;乙酸钠、甲醇及内源呼吸碳源对反硝化速率的影响     

Performance and microbial ecology of the hybrid membrane biofilm process for concurrent nitrification and denitrification of wastewater.

We report on a novel process for total nitrogen (TN) removal, the hybrid membrane biofilm process (HMBP). The HMBP uses air-supplying hollow-fibre membranes inside an activated sludge tank, with suppressed aeration, to allow concurrent nitrification and denitrification. We hypothesised that a nitrifying biofilm would form on the membranes, and that the low bulk-liquid BOD concentrations would encourage heterotrophic denitrifying bacteria to grow in suspension. A nitrifying biofilm was initially established by supplying an influent ammonia concentration of 20 mgN/L. Subsequently, 120 mg/L acetate was added to the influent as BOD. With a bulk-liquid SRT of only 5 days, nitrification rates were 0.85 gN/m(2) per day and the TN removal reached 75%. The biofilm thickness was approximately 500 lim. We used DGGE to obtain a microbial community fingerprint of suspended and attached growth, and prepared a clone library. The DGGE results, along with the clone library and operating data, suggest that nitrifying bacteria were primarily attached to the membranes, while heterotrophic bacteria were predominant in the bulk liquid. Our results demonstrate that the HMBP is effective for TN removal, achieving high levels of nitrification with a low bulk-liquid SRT and concurrently denitrifying with BOD as the sole electron donor.     

稻草强化生物膜浮床脱除工业尾水中氮素及COD的效果

工业污水处理厂排放的尾水中总氮含量偏高,容易引起地表水体的富营养化。为了提高尾水中总氮的去除效率,通过模拟稳定塘静态和动态试验,对比了不同稻草添加量(0,0.18,0.54 g/L)强化生物膜浮床脱除工业尾水中总氮(TN)的效果。静态试验结果表明:随着稻草量的增加,TN的去除率显著提高;10 d后,添加0(CK)、0.18 g/L(T1)和0.54 g/L(T2)稻草的尾水中,TN去除率分别为18%,40%,93%。动态试验结果显示,水力停留时间(HRT)为 4 d时,CK、T1和T2的平均TN去除率分别为10%,22%,49%,且3种情况下的进出水COD浓度无显著差异。这主要是由于稻草通过缓慢释放碳源为生物膜中异养反硝化细菌提供可利用的有机物。研究成果可为工业尾水深度处理脱氮技术提供参考。     

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。     

Real-time PCR quantification of nitrite reductase (nirS) genes in a nitrogen removing fluidized bed reactor.

Molecular approaches were applied to identify and enumerate denitrifying bacteria subsisting in a fluidized bed reactor (FBR). The FBR was continuously operated as a unit for the removal of nitrogen from the effluents of domestic sewage treatment plant, with an additional supply of methanol as a carbon source. By denaturing gradient gel electrophoresis (DGGE) and sequence analysis of 16S ribosomal RNA genes, Thauera group was found to be dominant among the denitrifying bacteria in the FBR sludge. Oligonucleotide probe THA155 for fluorescence in situ hybridization (FISH) was newly designed for specifically targeting the Thauera group. However, the THA155 signal obtained from the sludge was only 0.9-5.7% of the DAPI-stained total cells. The real-time polymerase chain reaction (PCR) targeting the sequences of nitrite reductase (NIR) gene, a key enzyme of denitrification processes, was performed to quantify the cells of denitrifying bacteria cells including the Thauera group in FBR sludge. An excellent correlation was obtained between the numbers of nirS genes and the activity of denitrifiers in the FBR sludge.     

Evaluation of hybrid processes for nitrification by comparing MBBR/AS and IFAS configurations.

An integrated fixed-film activated sludge (IFAS) pilot plant and a moving bed biofilm reactor coupled with an activated sludge process (MBBR/AS) were operated under different temperatures, carbon loadings and solids retention times (SRTs). These two types of hybrid systems were compared, focusing on the nitrification capacity and the nitrifiers population of the media and suspended biomass alongside other process performances such as carbonaceous and total nitrogen (TN) removal rates. At high temperatures and loadings rates, both processes were fully nitrifying and achieved similarly high carbonaceous removal rates. However, under these conditions, the IFAS configuration performed better in terms of TN removal. Lower temperatures and carbon loadings led to lower carbonaceous removal rates for the MBBR/AS configuration, whereas the IFAS configuration was not affected. However, the nitrification capacity of the IFAS process decreased significantly under these conditions and the MBBR/AS process was more robust in terms of nitrification. Ammonia oxidising bacteria (AOB) and nitrite oxidising bacteria (NOB) population counts accurately reflected the changes in nitrification capacity. However, significantly less NOBs than AOBs were observed, without noticeable nitrite accumulation, suggesting that the characterisation method used was not as sensitive for NOBs and/or that the NOBs had a higher activity than the AOBs.     

Potential nitrification and denitrification and the corresponding composition of the bacterial communities in a compact constructed wetland treating landfill leachates.

Constructed wetlands can be used to decrease the high ammonium concentrations in landfill leachates. We investigated nitrification/denitrification activity and the corresponding bacterial communities in landfill leachate that was treated in a compact constructed wetland, Tveta Recycling Facility, Sweden. Samples were collected at three depths in a filter bed and the sediment from a connected open pond in July, September and November 2004. Potential ammonia oxidation was measured by short-term incubation method and potential denitrification by the acetylene inhibition technique. The ammonia-oxidising and the denitrifying bacterial communities were investigated using group-specific PCR primers targeting 16S rRNA genes and the functional gene nosZ, respectively. PCR products were analysed by denaturing gradient gel electrophoresis and nucleotide sequencing. The same degree of nitrification activity was observed in the pond sediment and at all levels in the filter bed, whereas the denitrification activity decreased with filter bed depth. Denitrification rates were higher in the open pond, even though the denitrifying bacterial community was more diverse in the filter bed. The ammonia-oxidising community was also more varied in the filter bed. In the filter bed and the open pond, there was no obvious relationship between the nitrification/denitrification activities and the composition of the corresponding bacterial communities.     

Enhancement of oxygen transfer and nitrogen removal in a membrane separation bioreactor for domestic wastewater treatment.

Biological nitrogen removal in a membrane separation bioreactor developed for on-site domestic wastewater treatment was investigated. The bioreactor employed hollow fiber membrane modules for solid-liquid separation so that the biomass could be completely retained within the system. Intermittent aeration was supplied with 90 minutes on and off cycle to achieve nitrification and denitrification reaction for nitrogen removal. High COD and nitrogen removal of more than 90% were achieved under a moderate temperature of 25 degrees C. As the temperature was stepwise decreased from 25 to 5 degrees C, COD removal in the system could be constantly maintained while nitrogen removal was deteriorated. Nevertheless, increasing aeration supply could enhance nitrification at low temperature with benefit from complete retention of nitrifying bacteria within the system by membrane separation. At low operating temperature range of 5 degrees C, nitrogen removal could be recovered to more than 85%. A mathematical model considering diffusion resistance of limiting substrate into the bio-particle is applied to describe nitrogen removal in a membrane separation bioreactor. The simulation suggested that limitation of the oxygen supply was the major cause of inhibition of nitrification during temperature decrease. Nevertheless, increasing aeration could promote oxygen diffusion into the bio-particle. Sufficient oxygen was supplied to the nitrifying bacteria and the nitrification could proceed. In the membrane separation bioreactor, biomass concentration under low temperature operation was allowed to increase by 2-3 times of that of moderate temperature to compensate for the loss of bacterial activities so that the temperature effect was masked.     

Boosting nitrification with the BABE technology.

Over the past years there has been a growing interest for compact, simple, low cost and robust technologies to upgrade wastewater treatment plants for nitrogen removal. The BABE (Bio Augmentation Batch Enhanced) technology is such a new concept. This patented system for biological treatment of sludge liquor - the effluent produced from digested sludge - uses a new principle, boosting the nitrifying bacteria in a side stream in such a way that the activated sludge in the main process is augmented. This augmentation increases the nitrification capacity of the wastewater treatment plant (wwtp). Experiments on a practical scale have demonstrated the effective and stable operation of the BABE technology. Model studies supported by the results of the full-scale tests showed that the technology can be applied in several situations, i.e. 1) introducing nitrification at high loaded wwtps; 2) enhancing nitrification at wwtps with incomplete nitrification; 3) enlarging denitrification at wwtps with complete nitrification. Most likely this year a full-scale application will be realized in the Netherlands at a wwtp with insufficient nitrification throughout the year.     

Fluorescence in situ hybridization analysis of nitrifiers in piggery wastewater treatment reactors.

Fluorescence in situ hybridization (FISH) was performed to analyze the nitrifying microbial communities in an activated sludge reactor (ASR) and a fixed biofilm reactor (FBR) for piggery wastewater treatment. Heterotrophic oxidation and nitrification were occurring simultaneously in the ASR and the COD and nitrification efficiencies depend on the loads. In the FBR nitrification efficiency also depends on ammonium load to the reactor and nitrite was accumulated when free ammonia concentration was higher than 0.2 mg NH3-N/L. FISH analysis showed that ammonia-oxidizing bacteria (NSO1225) and denitrifying bacteria (RRP1088) were less abundant than other bacteria (EUB338) in ASR. Further analysis on nitrifying bacteria in the FBR showed that Nitrosomonas species (NSM156) and Nitrospira species (NSR1156) were the dominant ammonia-oxidizing and nitrite-oxidizing bacteria, respectively, in the piggery wastewater nitrification system.     

High nitrification rate at low pH in a fluidized bed reactor with chalk as the biofilm carrier.

A typical steady state bulk pH of about 5 was established in a nitrifying fluidized bed with chalk as the only buffer agent. In spite of the low pH, high rate nitrification was observed with the nitrification kinetic parameters in the chalk reactor similar to those of biological reactors operating at pH>7. Various methods were used to determine the reasons for high rate nitrification at such low pH including (i) determination of bacterial species, (ii) microsensor measurements in the biofilm, and (iii) comparison of nitrification performance at low pH with a non-chalk fluidized bed reactor. Fluorescence in situ hybridization (FISH) using existing 16S rRNA-targeted oligonucleotide probes showed common nitrifying bacteria in the low pH chalk reactor. The prevalent nitrifying bacteria were identified in the Nitrosomonas oligotropha, Nitrosomonas europeae/eutropha, Nitrosospira and Nitrospira related groups, all well known nitrifiers. Microelectrode measurements showed that the pH in the biofilm was low and similar to that of the bulk pH. Finally, reactor performance using a non-chalk biofilm carrier (sintered glass) with the same bacterial inoculum also showed high rate nitrification below pH 5. The results suggest that inhibition of nitrification at low pH is highly overestimated.