短程反硝化除磷工艺培养过程的群落结构分析

应用PCR-DGGE方法,对以亚硝酸盐为电子受体的反硝化除磷系统的培养驯化过程的微生物群落结构和多样性进行研究。试验结果表明:随着驯化的过程,工艺内部的微生物种群是在不断变化的;系统中稳定运行后,系统内微生物的群落结构差别不大,形成了较为稳定的微生物群落结构。     

外加常规碳源污水反硝化脱氮研究进展

针对外加碳源强化反硝化脱氮,论述了反硝化相关机理与动力学的研究进展,包括反硝化碳源投加量、反硝化动力学、污泥产率和亚硝酸盐积累问题。生物反硝化过程是多级反应过程,需要从电子供体多级传递、碳源生物代谢途径和微生物种群结构等角度综合分析研究。不同碳源条件下,反硝化动力学研究需从微生物结构和工艺运行条件等各个角度开展。在实现有效反硝化脱氮的同时,应注重二次污染的控制,如亚硝酸盐积累。     

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。     

曝气生物滤池内同步硝化反硝化的研究进展

笔者以1984—2009年发表在国内外期刊上的关于BAF研究与应用的多篇文献为基础,对曝气生物滤池中的同步硝化反硝化作用从宏观、微观和微生物角度进行机理分析,并从DO、C/N、pH以及滤料角度对影响脱氮过程的因素进行探讨,最后对曝气生物滤池同步硝化反硝化研究进行展望。     

同步硝化反硝化脱氮研究

在控制SBR反应器保持良好的好氧状态条件下 ,考察进水COD/NH3比值对同步硝化反硝化脱氮效率的影响。同时也对同步硝化反硝化机理进行了初步的探讨。研究表明 ,进水COD/NH3比值越高 ,总氮去除率越高 ,同步硝化反硝化现象越明显。由该试验可以推断活性污泥菌胶团中异养硝化菌和好氧反硝化菌的存在。     

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。     

短程硝化反硝化技术研究进展

综述了国内外短程硝化反硝化的技术进展。从短程硝化反硝化技术的影响因素、控制方式以及氨氧化菌的分子生物学研究等方面进行了分析,为在更普遍、更广泛的条件下实现短程硝化生物脱氮技术提供参考和支持。     

碳源对生物反硝化的影响

碳源对生物反硝化的影响主要表现为:①对于高浓度含氨氮废水(一般都需要投加碱),碳源不足会使反硝化过程的产碱量降低,这将增大其硝化过程的外加碱量;并且由于反硝化进行不彻底,使出水中存在大量的NO_2~,出水COD增大;②碳源种类对反硝化效果有较大影响,单一基质和混合废水对反硝化反应的进程有不同的影响。     

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DO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、NH4+-N、TN、TP的出水浓度达到一级A排放标准,得出最佳的DO控制...     

酒类废水特征及其作为反硝化碳源的可行性

研究了酒类废水作为污水处理厂反硝化碳源的可行性.首先分析了不同类型酒类废水的物化和微生物群落特征.活性污泥添加酒类废水后,反硝化速率为1.85～2.60 mgNO3-N/(gVSS.h),效果好于对照组乙酸钠(1.72).抑制性测试表明添加酒类废水对活性污泥的硝化速率、释磷和吸磷速率均无显著不利影响.残留COD测试表明添加酒类废水对出水COD的影响较小可控.碳源效率测试表明低浓度过滤酒类废水最佳,其碳源消耗质量比(△COD/△N)为7.1,低于对照组乙酸钠(10.9).综上所述,经过适当处理后的酒类废水是优质反硝化碳源.     

Partial ozonation of activated sludge to reduce excess sludge, improve denitrification and control scumming and bulking.

Disposal of sewage sludge is forbidden and agricultural use of stabilized sludge will be banned in 2005 in Switzerland. The sludge has to be dewatered, dried, incinerated and the ashes disposed in landfills. These processes are cost intensive and lead also to the loss of valuable phosphate resources incorporated in the sludge ash. The implementation of processes that could reduce excess sludge production and recycle phosphate is therefore recommended. Partial ozonation of the return sludge of an activated sludge system reduces significantly excess sludge production, improves settling properties of the sludge and reduces bulking and scumming. The solubilized COD will also improve denitrification if the treated sludge is recycled to the anoxic zone. But ozonation will partly inhibit and kill nitrifiers and might therefore lead to a decrease of the effective solid retention time of the nitrifier, which reduces the safety of the nitrification. This paper discusses the effect of ozonation on sludge reduction, the operation stability of nitrification, improvement of denitrification and gives also an energy and cost evaluation.     

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.     

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.     

城市污水生物除磷脱氮工艺中的矛盾关系及对策

目前 ,城市污水处理厂的处理对象包括COD、BOD5、SS和氮、磷等营养物质。就氮磷脱除而言 ,一般需涉及硝化、反硝化、微生物释磷和吸磷等过程。由于各过程的要求不同 ,在同一污水处理工艺系统中就不可避免地产生了各过程间的矛盾关系。针对泥龄问题、碳源问题、硝酸盐问题、系统的硝化和反硝化容量问题、释磷吸磷的容量问题进行了探讨     

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。     

The Role of Sediments in the Nitrogen Budget of Lower Green Bay,Lake Michigan

The extreme southern portion of Green Bay is a shallow (1 to 5 m depth), eutrophic water body which receives considerable nutrients from the Fox River and metropolitan Green Bay, Wisconsin. Research to evaluate the effect of sediments on nitrogen (N) in the bay entailed periodic sampling of waters and sediments at six sites over 20 months and laboratory investigations of the rates of nitrification, denitrification, mineralization, immobilization, and N₂ fixation. The monitoring data indicated that the N concentrations, approximately 0.6 and 0.8 mg/L of inorganic and organic N, respectively, in the bay waters are considerably higher than the threshold limits that may cause algal bloom and aquatic weed problems. Consideration of the available sediment N pool with respect to recognizable N inputs indicated that only 1.2 percent of the yearly N loading from the Fox River is present in the active sediment layer. Nitrification and subsequent denitrification at the sediment-water interface as a result of intermittent wind stirring could be a major sink for N, but presently it has a minor impact due to the high loading rate of N in this ecosystem. The study indicates that even if approximately 50 percent of the present point source loading of N were eliminated by pollution abatement, the N input from nonpoint sources (combined with existing concentrations of phosphorus in the bay waters) would be sufficient to maintain eutrophic conditions.     

Innovations in wastewater treatment: the moving bed biofilm process.

This paper describes the moving bed biofilm reactor (MBBR) and presents applications of wastewater treatment processes in which this reactor is used. The MBBR processes have been extensively used for BOD/COD-removal, as well as for nitrification and denitrification in municipal and industrial wastewater treatment. This paper focuses on the municipal applications. The most frequent process combinations are presented and discussed. Basic design data obtained through research, as well as data from practical operation of various plants, are presented. It is demonstrated that the MBBR may be used in an extremely compact high-rate process (<1 h total HRT) for secondary treatment. Most European plants require P-removal and performance data from plants combining MBBR and chemical precipitation is presented. Likewise, data from plants in Italy and Switzerland that are implementing nitrification in addition to secondary treatment are presented. The results from three Norwegian plants that are using the so-called combined denitrification MBBR process are discussed. Nitrification rates as high as 1.2 g NH4-N/m2 d at complete nitrification were demonstrated in practical operation at low temperatures (11 degrees C), while denitrification rates were as high as 3.5g NO3-Nequiv./m2.d. Depending on the extent of pretreatment, the total HRT of the MBBR for N-removal will be in the range of 3 to 5 h.     

Effects of Hydrological Flow Regime on Sediment-water Interface and Water Column Nitrogen Dynamics in a Great Lakes Coastal Wetland (Old Woman Creek,Lake Erie)

Sediment-water interface nitrogen (N) transformations and water column ammonium cycling rates were measured along a stream to lake gradient at three sites within Old Woman Creek (OWC) and one near-shore Lake Erie site during two hydrological regimes: one with open flow to the lake after a rain event (July 2003), and another with a sand barrier blocking flow (July 2004). Net N2 effluxes in OWC at all times and at the near-shore Lake Erie site in July 2003 suggest that sediments are a N sink via denitrification. Observed dissimilatory nitrate reduction to ammonium (DNRA) may counteract some of this N removal, particularly when the creek mouth is closed. Upstream, a closed creek mouth led to higher sediment oxygen demand, net N₂ flux, potential DNRA, and potential denitrification rates. The lake site exhibited lower rates of these processes with the creek mouth closed except denitrification potential, which was unchanged. Denitrification in OWC appeared to drive N limitation in the lower wetland when the sand barrier was blocking flow to the lake. Higher potential versus in situ denitrification estimates imply that water column NO₃⁻ limits and drives denitrification in OWC. Water column to sediment regeneration ratios suggest that sediment recycling may drive primary production in the OWC interior when the creek mouth is closed and new N inputs from runoff are absent, but more data are needed to confirm these apparent trends. Overall, hydrological regime in OWC appeared to have a greater impact on sediment N processes than on water column cycling.     

Potential of activated sludge ozonation.

The disposal of sewage sludge and the agricultural use of stabilised sludge are decreasing due to more stringent regulations in Europe. An increasing fraction of sewage sludge must therefore be dewatered, dried, incinerated and the ashes disposed of in landfills. These processes are cost-intensive and also lead to the loss of the valuable phosphate resources incorporated in the sludge ash. The implementation of processes that could reduce excess sludge production and recycle phosphate is therefore recommended. Partial ozonation of the return sludge of an activated sludge system significantly reduces excess sludge production, improves the settling properties of the sludge and reduces bulking and scumming. The solubilised COD will also improve denitrification if the treated sludge is recycled to the anoxic zone. However, ozonation partly kills nitrifiers and could therefore lead to a decrease of the effective solid retention time of the nitrifier, thus reducing the safety of the nitrification. This paper discusses the effect of ozonation on sludge reduction, the operating stability of nitrification, the improvement of denitrification and also presents an energy and cost evaluation.     

Potential of activated sludge disintegration.

The disposal of sewage sludge and the agricultural use of stabilised sludge are decreasing due to more stringent regulations in Europe. An increasing fraction of sewage sludge must therefore be dewatered, dried, incinerated and the ashes disposed of in landfills. These processes are cost-intensive and also lead to the loss of valuable phosphate resources incorporated in the sludge ash. The implementation of processes that could reduce excess sludge production and recycle phosphate is therefore recommended. Disintegration of biological sludge by mechanical, thermal and physical methods could significantly reduce excess sludge production, improve the settling properties of the sludge and reduce bulking and scumming. The solubilised COD could also improve denitrification if the treated sludge is recycled to the anoxic zone. However, disintegration partly inhibits and kills nitrifiers and could therefore shorten their effective solid retention time, thus reducing the safety of the nitrification. This paper discusses the potential of disintegration on sludge reduction, the operating stability of nitrification, the improvement of denitrification and also presents an energy and cost evaluation.