废水生物脱氮新工艺研究进展

对生物脱氮新工艺进行了较全面的综述,分析了影响NO2-N积累的主要因素为游离氨、pH值、温度、溶解氧、污泥龄和有害物质,主要介绍了短程硝化反硝化、厌氧氨氧化和CANON等生物脱氮新工艺的微生物学原理,研究应用现状、发展前景以及存在的问题。     

Electrochemical conversion characteristics of ammonia to nitrogen

In order to evaluate the electrolytic decomposition characteristics of ammonia to nitrogen, this work has studied several experimental variables of electrolytic ammonia decomposition. The effects of the pH and the chloride ion in the solution, kinds of anodes such as IrO(2,) RuO(2), and Pt on the electrolytic decomposition of ammonia were compared, and the existence of a membrane equipped in the cell, the changes of the current density, the initial ammonia concentration, and so on were investigated for the decomposition. The performances of the electrode were totally in the order of RuO(2) approximately IrO(2) > Pt in both the acid and alkali conditions. The ammonia decomposition was the highest at a current density of 80 mA/cm(2), over which it decreased, because the adsorption of the ammonia at the electrode surface was hindered by the hydroxyl ions in the solution. The ammonia decomposition yield increased with the concentration of the chloride ion in the solution. However, the increment rate became much lesser over 10 g/l of the chloride ion. The RuO(2) electrode among the tested anodes generated the most OH radicals which could oxidize the ammonium ion at pH 7.     

Identification and quantification of anammox bacteria in eight nitrogen removal reactors

Various studies have revealed anaerobic ammonium oxidation (anammox) as a very attractive alternative process suitable for nitrogen removal from wastewater. Here we investigated anammox bacteria in eight different nitrogen removal reactors. The diversity and abundance of anammox bacteria were determined by the 16S rRNA gene analysis, fluorescence in situ hybridization with specific probes and real-time quantitative PCR (qPCR). In these reactors, at least eight unique near full length anammox 16S rRNA gene sequences were detected, which were distributed over two genera; Candidati Brocadia and Kuenenia. FISH results confirmed that only one anammox bacterium dominated the community in each of the eight reactors investigated in this study. qPCR analysis revealed that anammox bacteria were present in seven of the reactors in the order of 10⁹ cells/ml and 10⁷ cells/ml in reactor A1. The dominant and divergent Brocadia-like anammox phylotype in one reactor represented a novel species for which we propose the name Candidatus Brocadia sinica. Taken together, these results indicated that a single seeding source could be used to seed anammox reactors designed to treat different types of wastewater, which could lead to a faster start-up of bioreactors.     

A/O-MBR系统的短程生物脱氮污水处理工艺研究

利用生物强化技术,通过接种短程硝化菌和亚硝酸反硝化菌于反应器中,构建了A/O-MBR短程生物脱氮污水处理工艺系统,并考察启动期和不同HRT下的运行效果。结果表明:A/O-MBR短程生物脱氮污水处理工艺启动时间短;在不同水力停留时间(HRT)时,MBR中的亚硝氮积累比率均能维持在0.95以上;AN具有很好的反硝化性能,出水NO2-和NO3-浓度均低于3mg/L。分析认为MBR中氨氧化菌维持优势地位是该工艺可实现良好的短程生物脱氮的原因。     

Partial ammonium oxidation to nitrite of high ammonium content urban landfill leachates

In an effort to treat N-rich streams in a more sustainable way, recent years have seen the development of new technologies, most of which are based on autotrophic denitrification via nitrite (anammox). In order to attain a suitable influent for that process, the wastewater must be treated by partially oxidising the ammonium to nitrite. In that aspect, this article presents the start-up and operation of a Partial Nitritation Sequencing Batch Reactor (PN-SBR) treating urban landfill leachates. Stable partial nitritation has been reached treating high ammonium loads (1-1.5 kg Nm(-3)d(-1)), demonstrating the feasibility of this technology as a previous step of anammox process. This study has also given away the importance of pH influence over ammonium oxidising bacteria (AOB) activity, thus it has been possible to determine the values of the half inhibition constants for free ammonia (k(I,FA)=605.48+/-87.18 mg N-NH L(-1)) and free nitrous acid (k(I,FNA)=0.49+/-0.09 mg N-HNO2 L(-1)), as well as the half-saturation constant for bicarbonate (k(HCO3-) = 0.01 +/- 0.16 mg CL(-1)).     

Study on a discrete-time dynamic control model to enhance nitrogen removal with fluctuation of influent in oxidation ditches

The aim of study was proposed a new control model feasible on-line implemented by Programmable Logic Controller (PLC) to enhance nitrogen removal against the fluctuation of influent in Carrousel oxidation ditch. The discrete-time control model was established by confirmation model of operational conditions based on a expert access, which was obtained by a simulation using Activated Sludge Model 2-D (ASM2-D) and Computation Fluid Dynamics (CFD), and discrete-time control model to switch between different operational stages. A full-scale example is provided to demonstrate the feasibility of the proposed operation and the procedure of the control design. The effluent quality was substantially improved, to the extent that it met the new wastewater discharge standards of NH₃-N < 5 mg/L and TN < 15 mg/L enacted in China throughout a one-day period with fluctuation of influent.     

Characteristics and fate of organic nitrogen in municipal biological nutrient removal wastewater treatment plants

The aim of this study was to investigate the occurrence and fate of colloidal and dissolved organic nitrogen (CON and DON) across biological nutrient removal (BNR) activated sludge bioreactors. Primary and secondary effluent total nitrogen (TN) measurements and component fractionation, CON and DON concentration profiles across BNR bioreactors, and laboratory batch experiments with the process mixed liquor were carried out at several full-scale BNR plants in northern Poland. The organic nitrogen (ON) components were divided into high CON, low CON, and DON based on sequential filtration through 1.2, 0.45 and 0.1 μm pore-size filters. The average influent DON_0.1μm (<0.1 μm) concentrations ranged from 1.1 g N/m³ to 3.9 g N/m³ and accounted for only 4-13% of total organic nitrogen. In the effluents, however, this contribution increased to 12-45% (the DON_0.1μm concentrations varied in a narrow range of 0.5-1.3 g N/m³). Conversions of ON inside the bioreactors were investigated in more detail in two largest plants, i.e. Gdansk (565,000 PE) and Gdynia (516,000 PE). Inside the two studied bioreactors, the largest reductions of the colloidal fraction were found to occur in the anaerobic and anoxic compartments, whereas an increase of DON_0.1μm concentrations was observed under aerobic conditions in the last compartment. Batch experiments with the process mixed liquor confirmed that DON_0.1μm was explicitly produced in the aerobic phase and significant amounts of ON were converted in the anoxic phase of the experiments.     

Fate of hormones and pharmaceuticals during combined anaerobic treatment and nitrogen removal by partial nitritation-anammox in vacuum collected black water

Vacuum collected black (toilet) water contains hormones and pharmaceuticals in relatively high concentrations (μg/L to mg/L range) and separate specific treatment has the potential of minimizing their discharge to surface waters. In this study, the fate of estrogens (natural and synthetical hormones) and pharmaceuticals (paracetamol, metoprolol, propranolol, cetirizine, doxycycline, tetracycline, ciprofloxacin, trimethoprim, carbamazepine, ibuprofen and diclofenac) in the anaerobic treatment of vacuum collected black water followed by nitrogen removal by partial nitritation-anammox was investigated. A new analytical method was developed to detect the presence of several compounds in the complex matrix of concentrated black water. Detected concentrations in black water ranged from 1.1 μg/L for carbamazepine to >1000 μg/L for paracetamol. Anaerobic treatment was only suitable to remove the majority of paracetamol (>90%). Metoprolol was partly removed (67%) during aerobic treatment. Deconjugation could have affected the removal efficiency of ibuprofen as concentrations even increased during anaerobic treatment and only after the anammox treatment 77% of ibuprofen was removed. The presence of persistent micro-pollutants (diclofenac, carbamazepine and cetirizine), which are not susceptible for biodegradation, makes the application of advanced physical and chemical treatment unavoidable.     

底曝式氧化沟脱氮除磷的运行控制

结合工程实例,探讨了底曝式氧化沟系统的MLSS、泥龄、DO等运行参数的控制问题,通过对各参数进行分析和优化调整,使该工艺不但具有良好的脱氮效率,而且具有较好的除磷效果。     

Sulfide-induced nitrate reduction in the sludge of an anaerobic digester of a zero-discharge recirculating mariculture system

The anaerobic digester is a vital component in a zero-discharge mariculture system as therein most of the organic matter is mineralized and nitrogen-containing compounds are converted to gaseous N₂. Although denitrification is a major respiratory process in this nitrate-rich treatment stage, also sulfate respiration takes place and may cause undesirable high sulfide concentrations in the effluent water. To examine the effect of sulfide on nitrate reduction, in situ depth profiles of inorganic nitrogen and sulfur compounds were determined. Additionally, nitrate reduction was examined as a function of ambient sulfide concentrations in sludge collected from different locations in the anaerobic reactor. Depth profiles showed high concentrations of nitrate and low concentrations of sulfide and ammonia in the aqueous layer of the reactor. A sharp decrease of nitrate and an increase in sulfide and ammonia concentrations was measured at the water-sludge interface. Nitrate reduction was highest in this interface zone with rates of up to 8.05 ± 0.57 μmol NO₃⁻ h⁻¹ g_(sludge)⁻¹. Addition of sulfide increased the nitrate reduction rate at all sludge depths, pointing to the important role of autotrophic denitrification in the anaerobic reactor. Dissimilatory nitrate reduction to ammonia (DNRA) was found to be low in all sludge layers but was enhanced when sludge was incubated at high sulfide concentrations. Although nitrate reduction rates increased as a result of sulfide addition to sludge samples, no differences in nitrate reduction rates were observed between the samples incubated with different initial sulfide concentrations. This as opposed to sulfide oxidation rates, which followed Michaelis-Menten enzymatic kinetics. Partial oxidation of sulfide to elemental sulfur instead of a complete oxidation to sulfate, could explain the observed patterns of nitrate reduction and sulfide oxidation in sludge incubated with different initial sulfide concentrations.     

Development of biological filter as tertiary treatment for effective nitrogen removal: Biological filter for tertiary treatment

A biological filtration process applicable to tertiary treatment of sewage for effective nitrogen removal was developed. It consisted of a nitrification filter (Filter 1) and/or a polishing filter with anoxic and oxic parts (Filter 2). A pilot plant set at a municipal sewage treatment plant was operated for 525 d with feed of real sewage. The maximum apparent nitrification rate in Filter 1 in winter was 0.54 kg N/m3- filter-bed d. In Filter 2, the maximum denitrification capacity was 4 kg N/m3 filter-bed d) in winter. SS was stably removed and high transparency water was obtained. The target water quality (SS, BOD, and T-N5 mg/L) was accomplished in winter with the LV of 202 m/d in Filter 2, which corresponds to 0.24 h of HRT. These results proved that this process is compact, stable, convenient to install, and cost effective to build and operate as tertiary treatment to remove nitrogen effectively.     

水质特性与Dephanox工艺脱氮除磷

结合Dephanox工艺的流程及特点,从基质类型和C/N比及C/P比两方面对Dephanox工艺脱氮除磷效果进行了分析,对Dephanox工艺存在的问题进行了探讨,提出该工艺有待解决的研究课题.     

Influence of operational parameters on nitrogen removal efficiency and microbial communities in a full-scale activated sludge process

To improve the efficiency of total nitrogen (TN) removal, solid retention time (SRT) and internal recycling ratio controls were selected as operating parameters in a full-scale activated sludge process treating high strength industrial wastewater. Increased biomass concentration via SRT control enhanced TN removal. Also, decreasing the internal recycling ratio restored the nitrification process, which had been inhibited by phenol shock loading. Therefore, physiological alteration of the bacterial populations by application of specific operational strategies may stabilize the activated sludge process. Additionally, two dominant ammonia oxidizing bacteria (AOB) populations, Nitrosomonas europaea and Nitrosomonas nitrosa, were observed in all samples with no change in the community composition of AOB. In a nitrification tank, it was observed that the Nitrobacter populations consistently exceeded those of the Nitrospira within the nitrite oxidizing bacteria (NOB) community. Through using quantitative real-time PCR (qPCR), nirS, the nitrite reducing functional gene, was observed to predominate in the activated sludge of an anoxic tank, whereas there was the least amount of the narG gene, the nitrate reducing functional gene.     

A／O同步脱氮除磷工艺试验研究

以模拟城市污水为研究对象,探讨了A／O同步脱氮除磷工艺的去除效果,并研究了DO、污泥龄、温度、pH值等参数对A／O同步脱氮除磷工艺的影响,得到了各工艺参数的最佳控制范围,以提高污水处理厂的运行效率。     

除磷脱氮鼓风曝气氧化沟工艺运行经验及管理

介绍了长治市污水处理厂污水处理工艺流程及设计参数,研究了除磷脱氮氧化沟工艺原理,分析了除磷脱氮的氧化沟工艺生产运行参数的影响因素,并总结了其运行情况及管理经验,指出该工艺技术合理,经济可行,具有广泛的推广价值。     

Enhanced ammonia nitrogen removal using consistent biological regeneration and ammonium exchange of zeolite in modified SBR process

The modified zeo-SBR is recommended for a new nitrogen removal process that has a special function of consistent ammonium exchange and bioregeneration of zeolite-floc. Three sets of sequencing batch reactors, control, zeo-SBR, and modified zeo-SBR were tested to assess nitrogen removal efficiency. The control reactor consisted of anoxic-fill, aeration-mixing, settling, and decanting/idle phases, meaning that nitrogen removal efficiency was dependent on the decanting volume in a cycle. The zeo-SBR reactor was operated in the same way as the control reactor, except for daily addition of powdered zeolite in the SBR reactor. The operating order sequences in the zeo-SBR were changed in the modified zeo-SBR. Anoxic-fill phase was followed by aeration-mixing phase in the zeo-SBR, while aeration-mixing phase was followed by anoxic-fill phase in the modified zeo-SBR to carry NH4(+)-N over to the next operational cycle and to reduce total nitrogen concentration in the effluent. In the modified zeo-SBR, nitrification and biological regeneration occurred during the initial aeration-mixing phase, while denitrification and ammonium adsorption occurred in the following anoxic-fill phase. The changed operational sequence in the modified zeo-SBR to adapt the ammonium adsorption and biological regeneration of the zeolite-floc could enhance nitrogen removal efficiency. As a result of the continuous operation, the nitrogen removal efficiencies of the control and zeo-SBR were in 68.5-70.9%, based on the 33% of decanting volume for a cycle. The zeo-SBR showed a consistent ammonium exchange and bio-regeneration in the anoxic-fill and aeration-mixing phases, respectively. Meanwhile, the effluent total nitrogen of the modified zeo-SBR showed 50-60 mg N/L through ammonium adsorption of the zeolite-floc when the influent ammonium concentration was 315 mg N/L, indicating the T-N removal efficiency was enhanced over 10% in the same HRT and SRT conditions as those of control and zeo-SBR reactors. The ammonium adsorption capacity was found to be 6-7 mg NH4(+)-N/g FSS that is equivalent to 40 mg NH4(+)-N/L of ammonium nitrogen removal.     

Comparison of control strategies for nitrogen removal in an activated sludge process in terms of operating costs: a simulation study

In this paper several control strategies for nitrogen removal are proposed and evaluated in a benchmark simulation model of an activated sludge process. The goal is to determine which control strategy delivers better performance with respect to plant operating costs. In the study, constant manipulated variables and various PI and feedforward control strategies are tested and compared with predictive control, which uses an ideal process model. The control strategies differ in the information used about the process (number of sensors and sensor location) and in the complexity of the control algorithms. To determine the set-points that yield optimal operating costs, an operational map is constructed for each control strategy. Results of the simulation show that with PI and feedforward controllers almost the same optimal operating costs can be achieved as with more advanced MPC algorithms under various plant operating conditions. More advanced control algorithms are advantageous only in cases where the plant is highly loaded and if stringent effluent fines are imposed by legislation.     

Removal of organics and nutrients from food wastewater using combined thermophilic two-phase anaerobic digestion and shortcut biological nitrogen removal

A process combining pilot-scale two-phase anaerobic digestion and shortcut biological nitrogen removal (SBNR) was developed to treat organics and nutrients (nitrogen and phosphorus) from food wastewater. The thermophilic two-phase anaerobic digestion process was investigated without adjusting the pH of the wastewater for the pre-acidification process. The digested food wastewater was treated using the SBNR process without supplemental carbon sources or alkalinity. Under these circumstances, the combined system was able to remove about 99% of COD, 88% of TN, and 97% of TP. However, considerable amounts of nutrients were removed due to chemical precipitation processes between the anaerobic digestion and SBNR. The average TN removal efficiency of the SBNR process was about 74% at very low C/N (TCOD/TN) ratio of 2. The SBNR process removed about 39% of TP from the digested food wastewater. Conclusively, application of the combined system improved organic removal efficiency while producing valuable energy (biogas), removed nitrogen at a low C/N ratio, and conserved additional resources (carbon and alkalinity).     

Advanced treatment of sewage by pre-coagulation and biological filtration process

A pre-coagulation and bio-filtration process for advanced treatment of sewage was developed and experimentally discussed with a pilot plant. The bio-filtration unit consists of a denitrification filter, a nitrification filter with side stream to the denitrification filter, and a polishing filter with anoxic and aerobic parts. Concentrations of SS, T-COD(Cr), T-carbonaceous BOD, T-N and T-P in the effluent were stably kept at less than 3, 20, 5mg/L, 2mg N/L and 0.2mg P/L, respectively, and transparency at higher than 100 cm, under total hydraulic retention time of 3.2h in the bio-filtration parts (filter-bed). ORP in an anoxic tank before a nitrification tank should be at a low level of less than -120 mV to keep remaining NO(-)(x) - N less than 1mg N/L, but must be maintained at a level higher than -150 mV. The maximum nitrogen-loading rate under a water temperature of 18 degrees C should be less than 0.25 kg N/(m(3)-filter-bed.d). Concentrations of microorganisms kept in the reactors were as high as 4000-5000 mg COD/L-filter-bed. Denitrification activity of 0.4 or 0.7 kg N/(m(3)-filter-bed.d), and nitrification activity of 0.3 kg N/(m(3)-filter-bed.d) were obtained, respectively, under a water temperature of about 18 degrees C. Backwashing in each tank as well as methanol addition and aeration in the polishing filter were operated successfully by the automatic control systems. These results proved that this process is applicable to advanced treatment of sewage with easy maintenance.