曝气条件对侧流活性污泥水解工艺脱氮性能和微生物的影响

通过改变传统厌氧/缺氧/好氧（A²/O）反应器和侧流活性污泥水解（SSH）反应器的曝气强度和溶解氧（DO）浓度,考察了曝气条件对脱氮性能的影响,并对比研究了微生物群落结构的变化规律。结果表明：相较于高DO阶段,两组反应器在中低DO阶段有更好的脱氮效果。在相同进水条件下,SSH反应器的脱氮性能优于A²/O反应器,且出水满足一级A标准。高通量测序结果表明,中低DO浓度更有利于脱氮微生物的生长。相对于A²/O反应器,SSH反应器中反硝化微生物的相对丰度更高。因此,合理控制曝气条件维持中低DO浓度有利于SSH工艺达到良好的脱氮性能及脱氮微生物的生长。     

Development of single-stage nitrogen removal using anammox and partial nitritation (SNAP) and its treatment performances.

Single-stage Nitrogen removal using Anammox and Partial nitritation (SNAP) process was newly developed as an economical nitrogen removal process for ammonium rich wastewaters. The experimental studies for the evaluation of SNAP process were carried out using a novel biofilm reactor, in which hydrophilic net-type acryl fiber biomass carrier was applied. This SNAP reactor was operated under operational conditions of pH 7.5-7.7, 35 degrees C and DO 2-3 mg/L, and 60 to 80% of influent NH4-N was removed under loading rate of 0.48 kg-N/m3/d. Through the DNA analysis of the attached sludge, it was made clear that ammonium oxidizing bacteria (AOB) and anammox bacteria coexisted in the attach-immobilized sludge on the acryl fiber biomass carrier. Favorable conditions for the growth of anammox bacteria were created inside attach-immobilized nitrifying sludge. Two kinds of anammox bacteria and two kinds of AOB were detected in the SNAP sludge. Existence ratios of anammox and AOB were estimated to be 15% and 8.7%, respectively, based on the obtained clone numbers. This coexisting condition was confirmed by the FISH image of SNAP sludge and its confocal laser scanning microscope.     

Formation and characteristics of nitritation granules cultivated in sequencing batch reactor by stepwise increase of N/C ratio

The cultivation of nitritation granules in sequencing batch reactor (SBR) by seeding conventional floccular activated sludge was investigated using ethanol-based synthetic wastewater. Reducing settling time offers selection pressure for aerobic granulation, and stepwise increase of influent N/C ratio can help to selectively enrich ammonia oxidizing bacteria (AOB) in aerobic granules. The spherical shaped granules were observed with the mean diameter of 1.25 mm, average settling velocity of 1.9 cm s(-1) and the sludge volume index (SVI) of 18.5-31.4 ml g(-1). After 25 days of operation, the nitrogen loading rate reached 0.0455 kg NH(4)(+)-N (kg MLSS·d)(-1), which was 4.55 times higher than that of the start-up period. The mature granules showed high nitrification ability. Ammonia removal efficiency was above 95% and nitrite accumulation ratio was in the range of 80-95%. The nitrifying bacteria were quantified by fluorescence in situ hybridization analysis, which indicated that AOB was 14.9 ± 0.5% of the total bacteria and nitrite oxidizing bacteria (NOB) was 0.89 ± 0.1% of the total bacteria. Therefore, AOB was the dominant nitrifying bacteria. It was concluded that the associated inhibition of free ammonia at the start of each cycle and free nitrous acid during the later phase of aeration may be the key factors to start up and maintain the stable nitritation.     

Analysis of nitrifying bacterial communities in aerobic biofilm reactors with different DO conditions using molecular techniques

In order to assess the relationship between the dissolved oxygen (DO) concentration and the characteristics of nitrifying bacterial communities in an aerobic biofilm reactor, molecular techniques including denaturing gradient gel electrophoresis (DGGE)/cloning based on PCR targeting 16S rRNA and the amoA gene and fluorescence in situ hybridisation (FISH) were conducted. The D-1, D-2, D-3 and D-4 reactors with different DO concentrations (1, 3, 5 and 7 mg/L, respectively) were set up in the thermostat and acclimated. The optimal DO concentration with stable nitrification efficiency was above 5.0 mg/L. As was shown by the results of DGGE and cloning, the community of ammonia-oxidising bacteria (AOB) and the ratio of Nitrosomonas sp. changed only slightly despite their differing nitrification efficiencies. The results of FISH indicated that higher DO concentrations resulted in an increase in AOB and nitrite-oxidising bacteria (NOB), and a reduction in heterotrophic microorganisms. The INT-dehydrogenase activity (DHA) test demonstrated that the activity of AOB decreased with reductions in the DO concentration. This means that the DO concentration does not influence the community of AOB, but rather the activity of AOB. In the relationship between the attached biomass and the nitrification efficiency, only the active biomass affected the nitrification efficiencies.     

污染河道水质强化脱氮生化工艺研究

应用生化工艺对河道污染水体进行修复是目前最经济的一条途径,但其面临的一个突出问题是在生物脱氮过程中可利用碳源不足,从而影响其处理效果。本研究采用分段进水生物接触氧化工艺来强化受污染水脱氮性能,与传统单点进水方式相比,两段进水对有机物和总氮去除率有显著提升,CODMn平均去除率从50.6%提升到66.3%;总氮平均去除率从31.4%提升到60.9%。沿程统计硝化细菌和反硝化细菌数量,硝化细菌主要集中在曝气区,数量为5.58×106,反硝化细菌主要集中在非曝气区的中后段,数量为6.49×105。同时检测沿程溶解氧和各氮素浓度,溶解氧浓度沿程降低,最后出水仅为0.2 mg/L;氨氮在曝气区转化为硝态氮,在非曝气区硝态氮还原成氮气,其结果进一步证实了硝化细菌和反硝化细菌的分布特征。     

Use of real-time PCR to examine the relationship between ammonia oxidizing bacterial populations and nitrogen removal efficiency in a small decentralized treatment system 'Johkasou'.

The aim of this study was to examine the relationship between ammonia oxidizing bacterial populations and biological nitrogen removal in a small on-site domestic wastewater treatment system "Johkasou". The population dynamics of ammonia oxidizing bacteria (AOB) in six full-scale advanced Johkasous was surveyed using real-time PCR assay over a period of one year. These Johkasous were selected to compare the AOB populations in different treatment performance. When the effluent NH4-N concentration was higher than 2 mg L(-1), it was difficult to meet the effluent standard of advanced Johkasous (T-N 10 mg L(-1)). In contrast, the nitrogen removal efficiency was hardly affected by nitrite oxidation and denitrification in these systems. In other words, ammonia oxidation was a rate-limiting step. Furthermore, we focused on the relationship between NH4-N loading per AOB cell and nitrogen removal. Real time PCR monitoring results demonstrated that it is important to regulate NH4-N loading per AOB cell below 210 pg cell(-1) day(-1) to meet the effluent standard of advanced Johkasou. It is considered that NH4-N loading per AOB cell is a useful parameter for determining suitable nitrogen loading and small decentralized system design.     

Study of the biological N removal over nitrite in a physico-chemical-biological treatment of digested pig manure in a SBR.

SBR technology is used to treat the supernatant from mesophilic anaerobic digestion of piggery wastewater. The novelty of the treatment consists in the use of a final coagulation/flocculation step inside the SBR cycle to reach the legal COD effluent standard. The pH changes introduced by the use of FeCl(3) do not affect the nitrifying activity. The SBR treatment includes a strategy to the control of oxygen supply and ammonia concentrations inside the digester to favor the biological nitrogen removal over nitrite, which makes the process more economical. The influence of several of these parameters on the AOB biomass activity is studied in this paper.     

林可霉素高浓度有机废水处理技术

采用厌氧颗粒和好氧活性污泥分别对内循环厌氧反应器(IC)和间歇式活性污泥法(SBR)进行污泥接种培养,研究水解酸化-IC-SBR工艺在林可霉素生产废水处理方面的运行效果。结果表明:在进水COD的质量浓度为6 000~9 000 mg/L,IC和SBR反应器中有机负荷分别为0.82 kg/(kg.d)和0.26 kg/(kg.d)左右的情况下,IC和SBR反应器分别运行60 d和7 d,COD平均去除率分别达到91%和61%,出水COD的质量浓度在300 mg/L以下,达到GB 8978—1996《污水综合排放标准》二级标准。     

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.     

An on-line optimisation of a SBR cycle for carbon and nitrogen removal based on on-line pH and Our: the role of dissolved oxygen control.

A pilot plant sequencing batch reactor (SBR) was applied in a wastewater treatment plant treating urban wastewater focused on carbon and nitrogen removal. From an initial predefined step-feed cycle definition, the evolution of the on-line monitored pH and calculated oxygen uptake rate (OUR) were analysed in terms of knowledge extraction. First, the aerobic phases of the SBR cycle were operated using an On/Off dissolved oxygen (DO) control strategy that concluded with a sinusoidal pH profile that made detecting the "ammonia valley" difficult. After changing to fuzzy logic control of the dissolved oxygen and by adding an air flow meter to the pilot plant, the pH evolution and on-line calculated OUR showed a clearer trend during the aerobic phases. Finally, a proposed algorithm for adjusting the aerobic phases of the SBR for carbon and ammonia removal is presented and discussed.     

Design and operation of SBR processes for small plants based on simulations.

The paper firstly presents an experimental study in a SBR pilot plant operated at 20 degrees C for nitrogen removal from a very small village wastewater. The plant consisted of only one reactor fed continuously throughout the day and aerated intermittently. Two tests with seven and three intermittences of mixing/aerated phases were conducted and verification of the results by simulations of the activated sludge model (ASM) was also carried out. The experimental results and simulation showed that a wide range of effluent N03-N can be obtained using different numbers of intermittences and values of the oxygen transfer coefficient (K(L)a). At the same time, the paper presents a design procedure for SBR processes based on an iterative process of simulations of the ASM model. After the selection of the cycle time, the mixing/aeration pattern, the initial volume, the solid retention time, and the duration of the phases, the simulation is undertaken, resulting in values for the effluent NH4-N and NO3-N, and the suspended solids before settling. Then, the latter parameters are verified to match the effluent and settling requirements. As an application of the design procedure, the effect on design and operation of different SBR configurations and of several operating conditions are analysed in three case studies.     

污水有机碳源和电子受体对除磷的影响

考察厌氧-缺氧SBR(A2SBR)工艺中主导生化反应过程及聚磷污泥的特性,为反硝化除磷脱氮工艺的应用提供运行控制参数.在稳定运行的A2SBR系统进水中分别投加NaAC和葡萄糖作为碳源,进行对比试验.结果表明,进水中的有机物越容易降解,反硝化除磷菌(DPB)厌氧释磷速率越快,后续的缺氧吸磷效果也越好.同时通过静态试验考察了不同浓度CODCr、NO3--N、不同类型电子受体对DPB反硝化除磷效果的影响.结果表明,进水CODCr为300 mg/L、NO3--N为60mg/L时反硝化除磷效果最佳,同时缺氧段瞬时投加NO3--N利于驯化DPB对NO2--N的适应性,可以实现DPB利用不同类型的电子受体进行吸磷作用.     

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.     

固定化细胞去除废水中硝态氮的试验研究

通过对常用的聚乙烯醇-硼酸固定化方法优化改进,有效解决了固定化细胞技术在废水处理领域推广应用中所面临的机械强度小、易破碎、发胀粘连和带气上浮等问题。对包埋固定化反硝化菌与未包埋反硝化菌处理含硝态氮的废水进行比较,结果表明:固定化反硝化菌在不适宜的pH值、温度和有氧条件下均比未包埋菌具有明显的耐受性,表现出良好的反硝化特性,并且能和硝化细菌在同一反应器中进行单级生物脱氮,总氮去除率达到52%,因而在处理含氮废水中具有一定的实际应用价值。     

Effect of inorganic carbon on nitrite accumulation in an aerobic granule reactor.

Pilot scale experiments were performed to evaluate the potential of nitrite type nitrification process with an airlift reactor and granular biomass. Initially, oxygen limitation was used as the main control parameter for accumulating nitrite in the effluent. After 30 d operation, the maximum nitrite conversion rate reached 2.5 kgNO2-N m(-3) d(-1), average diameter of the granule was 0.7 mm. Nitrite type reaction continued over 100 d, but nitrate formation increased after 150 d of operation. Once nitrate formation increased, oxygen limitation could not eliminate nitrite oxidising bacteria from granule. To overcome nitrate formation, laboratory scale batch experiments were conducted and it revealed a high concentration of inorganic carbon which had a significant effect on nitrite accumulation. Following this new concept, inorganic carbon was fed to the pilot scale reactor by changing pH adjustment reagent from NaOH to Na2CO3 and nitrite accumulation was recovered successfully without changing DO concentration. These results show that a high concentration of inorganic carbon is one of the control parameters for accumulating nitrite in biofilm nitrification system.     

SBR法处理煤化工废水中石油烃类的试验研究

采用序批式(SBR)活性污泥法处理煤化工废水.通过分析不同周期、进水浓度、pH、温度、DO与处理效果之间的关系,确定了SBR法处理煤化工废水的的最佳运行参数.试验结果表明,在SBR处理周期为24 h的条件下,进水CODCr为1200～1400 mg/L,石油烃类为50～70 mg/L,pH为6.8～7.1,DO为3.5 mg/L左右,温度约为25℃时,该工艺对CODCr和石油烃类去除效果较好,去除率分别为85％和76％.该工艺具有投资少、操作简单、运行费用低等特点.     

High rate nitrogen removal by the CANON process at ambient temperature

Completely autotrophic nitrogen removal over nitrite (CANON) is a cost-effective nitrogen removal process. Implementation of the CANON process relies on the cooperation of ammonium-oxidizing and Anammox bacteria, as well as the inhibition of nitrite-oxidizing bacteria. Strict limitations on dissolved oxygen (DO) concentration in the reactor, and the addition of sufficient inorganic carbon in the influent, were adopted as the main operational strategies. The reactor was fed with synthetic inorganic wastewater composed mainly of NH(4)(+)-N, and operated for 106 days. Stable nitrogen removal rates (NRR) of around 1.4 kg N m(-3) d(-1) were obtained at ambient temperature. Morphological characteristics and analysis of bacterial community confirmed the formation of functional outer aerobic and inner anaerobic granular sludge, providing evidence of stable nitrogen removal.     

The performance of a nitrogen-fixing SBR.

A laboratory study has successfully demonstrated that a nitrogen deficient thermomechanical pulping wastewater can be effectively treated in a sequencing batch reactor (SBR) operated under conditions of biological nitrogen fixation (the N-ViroTech process). In comparison to continuous stirred tank reactor activated sludge (CSTR-AS) configurations operated under either nitrogen fixing or nitrogen supplemented conditions, slightly lower removals of dissolved organic material were observed in the SBR. However, this was largely offset by significantly better suspended solids removal in the SBR, which contributes to the overall COD discharge. The settleability and dewaterability of sludge produced by the SBR was significantly better than that obtained from the nitrogen fixing CSTR-AS reactors, and comparable to that of a nitrogen supplemented system. Consistently low total and dissolved nitrogen discharges from the N-ViroTech systems demonstrated the advantage of this system over ones requiring nitrogen supplementation. The feast-famine regime of an SBR-type configuration has significant potential for the application of this technology in the treatment of nitrogen deficient waste streams, particularly those in which conventional single-stage systems may be susceptible to sludge bulking problems.     

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％。     

Domestic wastewater treatment with a small-scale membrane bioreactor.

A small-scale membrane plant for treating the domestic wastewater of a four-person household is presented. The membrane bioreactor has been in operation for 6 months and achieves elimination rates of 90, 95 and 80% for total organic carbon, chemical oxygen demand and total nitrogen, respectively. Only a small amount sludge is produced. The permeate is reused for flushing toilets and has a yellowish colour. After investigations of the effluent quality, decolourisation of the permeate, energy efficiency and control strategies in the first year, urine will be treated separately in an automated precipitation reactor where struvite is produced to improve the overall phosphate removal of the plant.