新型脱氮技术：一体化完全自养脱氮系统

从一体化完全自养脱氮工艺的反应机理、参与生化反应的微生物种群及其特点和一些试验结果等方面,综述了近年来国内外研究人员在生物脱氮方面的最新理论和试验成果,提出了一体化完全自养脱氮工艺的未来研究方向。     

BICT biological process for nitrogen and phosphorus removal.

An updated biological nitrogen and phosphorus removal process--BICT (Bi-Cyclic Two-Phase) biological process--is proposed and investigated. It is aimed to provide a process configuration and operation mode that has facility and good potential for optimizing operation conditions, especially for enhancing the stability and reliability of the biological nutrient removal process. The proposed system consists of an attached-growth reactor for growing autotrophic nitrifying bacteria, a set of suspended-growth sequencing batch reactors for growing heterotrophic organisms, an anaerobic biological selector and a clarifier. In this paper, the fundamental concept and operation principles of BICT process are described, and the overall performances, major operation parameters and the factors influencing COD, nitrogen and phosphorus removal in the process are also discussed based on the results of extensive laboratory experiments. According to the experimental results with municipal sewage and synthetic wastewater, the process has strong and stable capability for COD removal. Under well controlled conditions, the removal rate of TN can reach over 80% and TP over 90% respectively, and the effluent concentrations of TN and TP can be controlled below 15 mg/L and 1.0 mg/L respectively for municipal wastewater. The improved phosphorus removal has been reached at short SRT, and the recycling flow rate of supernatant between the main reactors and attached-growth reactor is one of the key factors controlling the effect of nitrogen removal.     

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.     

Modelling of biological nitrogen removal during treatment of piggery wastewater.

During this study, a mathematical model simulating piggery wastewater treatment was developed, with the objective of process optimisation. To achieve this, the effect of temperature and free ammonia concentration on the nitrification rate were experimentally studied using respirometry. The maximum growth rates obtained were higher for ammonium-oxidising biomass than for nitrite-oxidising biomass for the temperatures above 20 degrees C; values at 35 degrees C were equal to 1.9 and 1.35 day(-1), respectively. No inhibition of nitrification was observed for free ammonia concentrations up to 50 mgN/L. Using these data with others experimental data obtained from a pilot-scale reactor to treat piggery wastewater, a model based on a modified version of the ASM1 was developed and calibrated. In order to model the nitrite accumulation observed, the ASM1 model was extended with a two-step nitrification and denitrification including nitrite as intermediate. Finally, the produced model called PiWaT1 demonstrated a good fit with the experimental data. In addition to the temperature, oxygen concentration was identified as an important factor influencing the nitrite accumulation during nitrification. Even if some improvements of the model are still necessary, this model can already be used for process improvement.     

新型生物脱氮工艺的研究进展

氨氮废水是引起水体富营养化的主要因素。综述了传统生物脱氮的一般原理。介绍了生物脱氮领域最近开发的几种新工艺：SHARON、ANAMMOX、SHARON—ANAMMOX联合工艺、同时硝化一反硝化．为高效生物脱氮技术提供了新的理论和思路。     

曝气生物滤池去除有机物及氨氮的影响因素分析

采用以陶粒为填料的曝气生物滤池(BAF)处理生活污水,研究气水比、水力负荷、进水COD和NH3-N负荷对BAF去除COD及NH3-N的影响,分析COD及NH3-N沿滤柱的变化规律。结果表明:当试验进水COD及NH3-N质量浓度分别为300~370mg/L和20~40mg/L时,最佳气水比为4∶1~5∶1,最佳水力负荷为1.0~2.0 m3/(m2.h)。当进水COD负荷为1.69~6.47 kg/(m3.d)时,COD去除率与进水COD负荷成正相关。BAF的硝化性能与进水NH3-N和COD负荷成负相关。     

好氧反硝化生物脱氮研究进展

好氧反硝化新型生物脱氮理论的诞生,克服了传统生物脱氮工艺存在的不足,简化了流程,节省了投资和运行费用,提高了脱氮效率.初步探讨了好氧反硝化机理,从不同角度做了理论分析;阐述了有关好氧反硝化脱氮的研究进展;并对好氧反硝化应用前景做了展望,提出了好氧反硝化今后的研究方向重点应放在对好氧反硝化菌的筛选和驯化上,对于好氧反硝化的发生条件、反应中间产物及其反应机理等方面需要进行深入研究.     

Effects of silver nanoparticles on biological nitrogen removal processes

The effects of silver (Ag) nanoparticles (NPs) on activated sludge in a biological nitrogen removal (BNR) process were investigated under aerobic and anoxic conditions. We show that nitrification was more vulnerable to Ag NPs exposure than denitrification at the same Ag NPs concentration. In continuous operation of the BNR process, a higher inhibitory effect on nitrification was attributed to a smaller size of Ag NPs. About 70-90% of the Ag NPs supplied were embedded in the sludge matrix but 10-30% of the Ag NPs remained in the supernatant. This indicates that significant amounts of Ag NPs could be discharged from wastewater treatment plants and potentially impact on aquatic ecosystems.     

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.     

复合式曝气生物滤池脱氮效果影响因素研究

以某城市污水处理厂二级出水为原水,通过中试研究了复合式曝气生物滤池(CBAF)用于再生水回用的脱氮效果的主要影响因素,包括碳源投加量、气水比和水力负荷。试验结果表明,当碳源投加量为15～25mgCODCr/L,气水比为2:1,水力负荷为10m3/(m2.h)时,CBAF运行工况最优,脱氮性能稳定良好。当进水氨氮浓度为1.0～17.4mg/L,总氮浓度为7～23mg/L时,出水氨氮浓度始终低于2mg/L,总氮浓度低于15mg/L,出水水质满足《城市污水再生利用景观环境用水水质》(GB/T18921—2002)的相关要求。     

Factors affecting nitrogen removal by nitritation/denitritation.

Nitrogen removal from wastewater with high nitrogen concentration and low COD/N ratio via nitrite is advantageous. The specific character of the sludge liquor enables the application of such a method. The factors affecting process efficiency were studied. From the factors followed pH, NH4+/NH3 and NO2-/HNO2 concentration and distribution seem to be most important, using sequencing batch reactor technology and treating wastewater with high NH4+ concentration (above 1 g/l). The efficient oxidation of N-NH4+ to nitrite was achieved at a minimal nitrate production. Primary sludge was used as an internal source of substrate for the denitritation because of the organic substrate deficiency of the sludge liquor. The denitritation can be controlled by dosing of the primary sludge and can be complete. There are two operational alternatives of sludge liquor pretreatment: without pH control--lower operational costs and N-removal up to 65% and with pH control--higher operational costs and N-removal close to complete.     

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.     

SH-A节能型生物脱氮工艺处理焦化废水工程实例

采用SH-A节能型生物脱氮工艺处理氨氮含量高、有机物可生化性差的焦化废水。工程处理水量为1600m3/d。进水CODCr约2500mg/L,NH3—N约260mg/L。处理后出水各项指标均达到了《污水综合排放标准》(GB8978—1996)一级标准,其中CODCr≤100mg/L,NH3—N≤15mg/L。     

Biological phosphorus and nitrogen removal with biological aerated filter using denitrifying phosphorus accumulating organism.

In order to accomplish the biological nutrient removal with a weak sewage at low temperature, a hybrid process consisted of anoxic denitrifying phosphorus accumulating organism (dPAO) and nitrifying biological aerated filter (BAF) was studied in both lab and field pilot plants with weak sewage. The biofilm BAF was used as a post-nitrification process that provided sufficient nitrate to suspended growth dPAO. The anoxic/BAF configuration could remove nitrogen and phosphorus appreciably compared to other BNR systems. The enhanced biological phosphorus removal (EBPR) was mainly occurred in anoxic zone of suspended growth reactor. It has been found that P removal efficiency of dPAO was enhanced with an addition of a short oxic zone in suspended reactors compared to that of without oxic zone. However, the degree of aerobic P uptake in oxic zone was far lower than anoxic P uptake. The operating results of field plant indicated that dPAO/BAF configuration successfully reduced the adverse temperature effects at lower than 15 degrees C.     

Significance of denitrifying enzyme dynamics in biological nitrogen removal processes: a simulation study.

Activated Sludge Model No. 1 (ASM1) was extended to include the enzyme kinetics of denitrifying bacteria switching between oxygen and nitrate as electron acceptors. The extended ASM1 (eASM1) model was applied to two different periodic process configurations, fed-batch and Biodenipho, commonly used for nitrogen removal from wastewater. Predictions of optimal unaerated volume fraction (UVF) by eASM1 were similar to those by ASM1 for both the fed-batch and Biodenipho processes. However, eASM1 predicted substantially longer optimal cycle lengths than ASM1 for both processes. Predictions of optimal UVF and cycle length for the Biodenipho process by eASM1 were closer to current operational values for the University of Florida Biodenipho process than predictions by ASM1.     

SBR生物脱氮运行控制方式的优化

分析SBR系统处理城市污水的主要工艺参数及其对脱氮效果的影响。试验了多种运行控制方式,结果表明:①运行周期6 h,SBR即可较好地完成污水有机物氧化和同时脱氮;将闲置阶段设置在进水和曝气两阶段之间,可大幅度提高TN的去除率。②闲置时间会影响脱氮效果,最佳闲置时间为30 min;增加污泥负荷,可提高TN的去除率,但会降低NH3-N的硝化效果。     

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.     

New anaerobic process of nitrogen removal.

This paper reports on successful laboratory testing of a new nitrogen removal process called DEAMOX (DEnitrifying AMmonium OXidation) for the treatment of strong nitrogenous wastewater such as baker's yeast effluent. The concept of this process combines the recently discovered ANAMMOX (ANaerobic AMMonium OXidation) reaction with autotrophic denitrifying conditions using sulfide as an electron donor for the production of nitrite within an anaerobic biofilm. The achieved results with a nitrogen loading rate of higher than 1,000 mg/L/d and nitrogen removal of around 90% look very promising because they exceed (by 9-18 times) the corresponding nitrogen removal rates of conventional activated sludge systems. The paper describes also some characteristics of DEAMOX sludge, as well as the preliminary results of its microbiological characterization.     

生物颗粒活性炭处理苯酚废水

研究了生物颗粒活性炭(BGAC)处理合成苯酚废水的效果和机理。结果表明,BGAC能够高效处理苯酚废水,处理效果优于活性污泥法和颗粒活性炭(GAC)吸附。BGAC、活性污泥和GAC分别对75 mg/L的苯酚废水连续处理,平均去除率分别为98%、60%和90%。通过苯酚出水pH值和反应器中溶解氧的变化情况分析,BGAC对苯酚废水的处理主要借助于活性炭的吸附和微生物降解的交替作用。