Bioaugmentation of two-stage aerobic sequencing batch reactor with mixed strains for high nitrate nitrogen wastewater treatment

Mixed strains Delftia sp.YH01 and Acidovorax sp.YH02, with capability of heterotrophic nitrification-aerobic denitrification, were introduced into a two-stage aerobic sequencing batch reactor to enhance NO₃^--N removal. With optimal C/N of 8, efficient NO₃^--N removal was achieved at initial NO₃^--N concentration of 2000 mg·L^-1. Meanwhile, the massive accumulation of NO₂^--N was avoided during the long operation. Compared to the one-stage aerobic sequencing batch reactor, the removal efficiency of NO₃^--N and TN in the two-stage aerobic sequencing batch reactor was increased by 36.5% and 42.7%, which respectively was 93.8% and 88.4%. Microbial community study showed that the mixed strains have the stronger viability and can synergistically denitrify with the indigenous microorganisms in system, such as Azoarcus, Uncultured Saprospiraceae, Thauera, Paracocccus, which could be major contributors for aerobic denitrification. The proposed technology was shown to achieve high-efficiency treatment of high NO₃^--N wastewater through aerobic denitrification.     

甲醇为碳源时C/N对反硝化过程中亚硝酸盐积累的影响

如何获得稳定的NO2--N作为厌氧氨氧化细菌的电子受体是城镇污水通过厌氧氨氧化途径脱氮的瓶颈问题。为此考虑利用反硝化途径获取稳定的NO2--N。以甲醇为碳源,采用小试装置的SBR反应器,通过控制进水C/N(COD与NO3--N质量浓度比)的策略,研究了反硝化过程中的NO2--N积累的状况。试验结果表明以甲醇为碳源且投加量不足时(C/N3.2),反硝化过程中和反硝化结束后会产生稳定的NO2--N积累;在C/N不足的前提下,NO2--N积累量随甲醇投加量的增加而增加;进水C/N为2.4～3.2时,可获得约25%的NO2--N积累率;进水C/N为0.8时,NO2--N积累率仅为5.6%;C/N1时,NO2--N与NO3--N的还原速率随着COD浓度的增加而增加;C/N≥1时,COD浓度不再影响NO2--N与NO3--N的还原速率。     

Simultaneous removal of carbon,nitrogen and phosphorus from wastewater by coupling two-step anaerobic digestion with a sequencing batch reactor

The objective of this study was to develop an integrated process for simultaneous removal of carbon, nitrogen and phosphorus from industrial wastewaters. The process consisted of a-two step anaerobic digestion reactor, for carbon removal, coupled with a sequencing batch reactor (SBR) for nutrient removal. In the proposed process, carbon is eliminated into biogas by anaerobic digestion: acidogenesis and methanogenesis. The volatile fatty acids (VFA) produced during the first step of anaerobic digestion can be used as electron donors for both dephosphatation and denitrification. In the third reactor (SBR) dephosphatation and nitrification are induced through the application of an anaerobic–aerobic cycle. This paper describes the first trials and experiments on the SBR and a period of 210 days during which the SBR was connected to the acidogenic and methanogenic reactors. It was shown that nitrification of ammonia took place in the SBR reactor, during the aerobic phase. Furthermore, denitrification and VFA production were achieved together in the acidogenic reactor, when the efflux of nitrates from the SBR reactor was added to the first reactor influx. The proposed process was fed with a synthetic industrial wastewater, the composition of which was: total organic carbon (TOC)=2200 mg dm⁻³, total Kjeldahl nitrogen (TKN)=86 mg dm⁻³, phosphorus under phosphate form (P-PO₄)=20 mg dm⁻³. In these conditions, removals of carbon, nitrogen and phosphorus were 98%, 78% and 95% respectively. The results show that the combination of the two-step anaerobic digestion reactor and an SBR reactor is effective for simultaneous carbon, nitrogen and phosphorus removal. Reactor arrangements enabled zones of bacterial populations to exist. Complete denitrification occurred in the acidogenic reactor and hence the anaerobic activity was not reduced or inhibited by the presence of nitrate, thus allowing high TOC removal. Stable phosphorus release and phosphorus uptake took place in the SBR after coupling of the three reactors. A fast-settling compact sludge was generated in the SBR with the operational conditions applied, thus giving good separation of supernatant fluid. The benefits from this process are the saving of (i) an external carbon source for denitrification and phosphorus removal, (ii) a reactor for the denitrification step. © 1998 Society of Chemical Industry     

Biological nutrient removal with volatile fatty acids from food wastes in sequencing batch reactor

Volatile fatty acids (VFAs) derived from food waste were used as an alternative carbon source in biological nutrient removal. The pH Profiles were monitored during the nutrient removal in an Na-acetate fed sequencing batch reactor (SBR) (C source). Effluent N, P and SCOD concentrations of 0.5 and 0.1 mg/L were achieved with 5.5 hour of HRT (hydraulic retention time) when influent concentrations of NH₄⁺-N, PO₄³⁻ and SCOD were 42.5, 5.92 and 180 mg/L. Then the SBR was fed with four solutions of VFAs produced under different acidogenesis conditions of food wastes. VFAs-added SBR showed similar specific nitrification rates (3.0 to 3.9 mg-N/g MLSS · h) to that of acetate, but specific denitrification rates (3.2 to 4.2 mg NO₃⁻N/g MLSS·h) were slightly lower than with acetate of 4.67 mg NO₃⁻-N/g MLSS·h. VFAs-introduced SBR efficiently removed phosphorus except when the SBR was fed with a VFA-solution containing high amounts of valerate and caproate.     

厌氧复合床处理模拟焦化废水的反硝化动力学

采用厌氧复合床(UBF)处理模拟焦化废水,进水中投加NaNO₃模拟硝化液回流,实现了同时反硝化/产甲烷,COD去除率达到94%,NO₃^--N去除率达到99%。取复合床下部污泥做反硝化动力学研究,在存在亚硝酸盐积累的情况下,以NO₃^--N+0.6NO₂^--N作为反硝化电子受体,采用双基质的Monod方程对实验数据进行拟合,拟合曲线与实验测定值相关性良好。其次,采用双基质的Monod微分方程组对NO₃^--N和NO₂^--N的浓度变化进行拟合,得到相关参数:硝态氮的最大比降解速率和半饱和常数分别为1.13 d^-1和2.0 mg·L^-1;亚硝态氮的最大比降解速率和半饱和常数分别为0.66 d^-1和2.5 mg·L^-1,基于硝态氮和亚硝态氮的有机物半饱和常数分别为90.8 mg·L^-1和96.8 mg·L^-1。     

Enhancing completely autotrophic nitrogen removal over nitrite by trace NO2 addition to an AUSB reactor

BACKGROUND: Completely autotrophic nitrogen removal over nitrite (CANON) could decrease energy consumption and CO₂ release compared with conventional nitration–denitrification. Trace NO₂ addition could enhance the activities of aerobic and anaerobic ammonium oxidation. RESULTS: An aerated upflow sludge bed (AUSB) reactor inoculated simultaneously with aerobic and anaerobic ammonium oxidizing sludge was operated to cultivate granular sludge capable of carrying out CANON. The results showed that the efficiency and rate of total nitrogen (TN) removal reached 61% and 0.114 kgN, respectively (m^?3 day^?1) for DO = 0.5–0.6 mg L^?1. Batch tests indicated that trace NO₂ addition could increase the CANON activity of sludge. The TN removal rate and efficiency of the reactor was increased to 0.234 kgN m^?3 day^?1 and 63%, respectively, when the reactor was aerated with air containing 2.7–3.3 mmol m^?3 NO₂ and DO was at 0.5–0.8 mg L^?1. CONCLUSIONS: Trace NO₂ addition provides an alternative to increase the capacity of a CANON system at low DO concentration. Copyright © 2009 Society of Chemical Industry     

短程硝化颗粒污泥SBR的快速启动与维持

为探究短程硝化污泥快速颗粒化的最佳条件,采用SBR反应器,在温度28℃,曝气量0.2m3.h-1,溶解氧(DO)2.0mg·mL-1,污泥龄(SRT)为15d的运行工况下,缩短沉降时间为2min,通过以pH作为氨氧化过程的控制参数,优化曝气时间,防止过曝气,经过80周期(19d)成功实现短程硝化絮状污泥的颗粒化,并维持稳定。形成的颗粒污泥粒径在1.5～2.0mm之间,对COD和氨氮的去除率分别达到80%和95%,亚硝酸盐积累率(NO2--N/NOx--N)平均达到95%。分子生物学FISH技术对颗粒污泥菌群结构的定量分析表明,AOB依旧是优势菌群,约占17.8%左右,NOB占0.6%。曝气初期FA的抑制和实时控制是启动和维持颗粒污泥短程硝化性能的主要原因。     

Evaluation of an Integrated System for Pig Slurry Treatment

A system for pig slurry treatment, where anaerobic digestion, nitrification and denitrification have been integrated in a unique process treatment, has been investigated. This configuration allowed both removal of Chemical Oxygen Demand (COD) and a decrease in nitrogen content. Strategies are reported to bring enough COD to the denitrification system. Results (90% reduction in COD, 99·8% reduction in NH₄⁺-N and 98·8% reduction in NO₃⁻N) show this process could be considered a good alternative to treat these wastes. © 1997 SCI.     

Effect of supplying a carbon extracting solution on denitrification in horizontal subsurface flow constructed wetlands

Denitrification strongly depends on the availability of carbon source in constructed wetlands (CWs). In this study, several relevant carbon source extracting solutions made from hydrolyzate of selected wetland litters were added to CWs for nitrogen removal enhancement. The feasibility of supplying a carbon extracting solution to improve potential denitrification rate in horizontal subsurface flow constructed wetland was deeply investigated. Combinations of different hydraulic retention time (HRT, especially for 2-day and 4-day) with different influent COD/N ratios were designed to prove the enhancement on denitrification by carbon source supplement. In addition, specific denitrification rate (SDNR) was calculated for the comparison of the nitrogen removal at different COD/N ratios. The sequential operation results on total nitrogen (TN) and nitrate (NO ₃ ^? -N) removal efficiencies were obtained in CW system with an influent COD/N ratio of 4.0. The accumulation of nitrite (NO ₂ ^? -N) was found to be closely related to the removal of NO ₃ ^? -N. Meanwhile, no obvious accumulation of NO ₂ ^? -N was found when the removal of NO ₃ ^? -N was relatively high.     

SBR好氧污泥颗粒的脱氮性能研究

The sequencing batch reactor （SBR） was started up by seeding the anaerobic granular sludge and the aerobic granular sludge was successfully cultivated. The performance characteristic of the aerobic granules for nitrogen removal was investigated in detail. The experimental results demonstrated the relationship between operational parameters [dissolved oxygen （DO） and pH] and variation of chemical oxygen demand （COD）, ammonium （NH4^＋-N） and total nitrogen （TN）. In continuous flow pattern, COD was too low in the reactor at the later stage of a cycle, which restrained denitrification and decreased the removal of nitrogen, while in discontinuous flow pattern, the carbon source could be supplemented in time, which improved denitrification and increased the removal of TN from 66% to 81%.     

Performance and sludge characteristics of anammox process at moderate and low temperatures

A sequencing batch reactor (SBR) was used to investigate the performance and sludge characteristics of anammox process at moderate and low temperatures. The initial pH was 7.5 and hydraulic retention time (HRT) was 3 h. When temperature was 25-35 °C, nitrogen removal rate (NRR) fluctuated from 1.67 to 1.82 kg/m³·d. However, when temperature dropped to 15 °C, NRR suddenly decreased by 0.48 kg/m³·d. Larger activation energy was acquired at lower temperature, and it was difficult to achieve efficient nitrogen removal under low temperature. When temperature declined to 10 °C, ΔNO ₂ ^? -N/ΔNH ₄ ⁺ -N and ΔNO ₃ ^? -N/ΔNH ₄ ⁺ -N reached 1.02 and 0.27, respectively. Inhibition resulting from low temperature on anammox activity was recoverable, and the modified Boltzmann model was appropriate to analyze recovery feature of anammox process. Low temperature not only led to poor nitrogen removal, but also affected sludge size and feature.     

缺氧环境对颗粒污泥强化除磷系统释磷的影响

以除磷颗粒污泥为研究对象,采用批次试验,以混合丙酸和乙酸（2∶1）为外加碳源,在厌氧起始阶段投加不同浓度的NO^-₃-N（0, 20, 30, 50和75 mg·L^-1, pH=8.0）和NO^-₂-N（10,20,40和60 mg·L^-1, pH=7.0, 7.5和8.0）,研究缺氧环境对颗粒污泥强化除磷系统释磷的影响。结果表明,硝态氮的投加对聚磷菌释磷无明显抑制,系统中VFA的吸收、磷的释放和硝态氮的反硝化同时发生,挥发性脂肪酸（相似文献   

Simultaneous desulfurization and denitrification of flue gas by pre-ozonation combined with ammonia absorption

A process of simultaneous desulfurization and denitrification of flue gas was conducted in this study. The flue gas containing 200 mg·m⁻³ NO, 1000–4000 mg·m⁻³ SO₂, 3%–9% O₂, and 10%–20% CO₂ was first oxidized by O₃ and then absorbed by ammonia in a bubbling reactor. Increasing the ammonia concentration or the SO₂ content in flue gas can promote the absorption of NO_X and extend the effective absorption time. On the contrary, both increasing the absorbent temperature or the O₂ content shorten the effective absorption time of NO_X. The change of solution pH had substantial influence on NO_X absorption. In the presence of CO₂, the NO_X removal efficiency reached 89.2% when the absorbent temperature was raised to 60 °C, and the effective absorption time can be maintained for 8 h, which attribute to the buffering effect in the absorbent. Besides, both the addition of Na₂S₂O₃ and urea can promote the NO_X removal efficiency when the absorbent temperature is 25 °C, and the addition of Na₂S₂O₃ had achieved better results. The advantage of adding Na₂S₂O₃ became less evident at higher absorbent temperature and coexistence of CO₂. In all experiments, SO₂ removal efficiency was always above 99%, and it was basically not affected by the above factors.     

Effect of COD/NO3-N ratio on the performance of a hybrid UASB reactor treating phenolic wastewater

The effect of COD/O₃⁻-N ratio on the biodegradation of complex phenolic mixture was studied in bench scale hybrid upflow anaerobic sludge blanket (HUASB) reactors. HUASB reactor is a combination of a UASB unit at the lower part and an anaerobic fixed film at the upper end. The aim of this study was to evaluate the biodegradability of phenolic mixture (from synthetic coal wastewater) as the only carbon and energy source in continuous experiments using nitrate as the final electron acceptor. Synthetic coal wastewater contained phenol (490 mg/L); m-,o-,p-cresols (123.0 mg/L, 58.6 mg/L, 42 mg/L); 2,4-, 2,5-, 3,4- and 3,5 dimethyl phenols (6.3 mg/L, 6.3 mg/L, 4.4 mg/L and 21.3 mg/L) as major phenolic compounds representing the complex phenolic mixture. Nitrate nitrogen loading was increased from 0.11 g/m³/d to 0.5 g/m³/d in order to keep COD/NO₃⁻-N ratio as 20.1, 14.85, 9.9, 6.36 and 4.45. An input phenolics concentration of 752 mg/L and hydraulic retention time (HRT) of 24 h was maintained through out the study. Removal of phenolic mixture was found to increase with the lowering of COD/NO₃⁻-N ratio. Maximum phenolics removal of 98% was achieved at a COD/NO₃⁻-N ratio of 6.36. However, phenolics removal got adversely affected when COD/NO₃⁻-N ratio was reduced below 6.36. A nitrogen production efficiency of 78% was obtained according to nitrate consumption. Simultaneous denitrification and methanogenesis was observed in all the reactors throughout the study, demonstrating that denitrification is a feasible alternative for the treatment of coal wastewater. Granules degrading complex phenolic mixture were of diameter 1.6–2.25 mm.     

Deterioration of denitrification by oxygen and cost evaluation of electron donor in an uncovered pre-denitrification process

Specific nitrate uptake rates (SNURs) under two test conditions were measured to evaluate effects of oxygen inhibition on denitrification. A test condition was that activated sludge was completely prevented from contacting of oxygen (SNUR _closed ), the other was that activated sludge was contacted to free air (SNUR _open ). Municipal wastewater and acetate were used as electron donors. SNUR _closed was 2.42 mg NO₃-N/g VSS-hr and SNUR _open was 1.09 mg NO₃-N/g VSS-hr when municipal wastewater was used as electron donor. Meanwhile, when acetate was used as electron donor, SNUR _closed was 24.65 mg NO₃-N/g VSS-hr and SNUR _open was 18.00 mg NO₃-N/g VSS-hr. The operating costs for electron donors were calculated based on the unit price of acetate to remove nitrate. When municipal wastewater was used as electron donor the ratio of cost _open to cost _closed was 0.45. Cost evaluation showed the adverse impacts on denitrification and explained why an anoxic reactor should be sequestered from oxygen.     

自养脱氮工艺有机物去除段与硝化段精确分离的实现与实时控制

为了实现城市污水处理过程中的节能降耗,提出了三段式城市污水自养脱氮工艺,阐述了除有机物SBR在整套工艺中的重要地位,探讨了不同曝气量与污泥浓度条件下,除有机物SBR中有机物的去除特征与规律。结果表明,在不同的曝气量及污泥浓度条件下,COD降解结束前NO₂^--N与NO₃^--N的浓度均低于0.1 mg·L^-1,反应器进入COD难降解阶段后,NO₂^--N与NO₃^--N的浓度快速提高,可以认为在除有机物SBR内有机物的去除和硝化过程是分步进行的,即先进行有机物的去除,而后进行硝化过程。DO曲线与pH曲线的突越点与除有机物过程的终点始终保持一致,可将其作为实时控制参数监测有机物的去除终点,对好氧曝气过程进行实时控制。     

Characteristics of nitrogen and phosphorus removal in SBR and SBBR with different ammonium loading rates

Laboratory scale experiments were conducted to study the deterioration of enhanced biological phosphorus removal (EBPR) due to influent ammonium concentration, and to compare the performance of two types of sequencing batch reactor (SBR) systems, a conventional SBR and sequencing batch biofilm reactor (SBBR). Both in SBR and SBBR, the total nitrogen removal efficiency decreased from 100% to 53% and from 87.5% to 54.4%, respectively, with the increase of influent ammonium concentration from 20 mg/l to 80 mg/l. When the influent ammonium concentration was as low as 20 mg/l (C: N: P=200: 20: 15), denitrifying glycogen-accumulating organisms (DGAOs) were successfully grown and activated by using glucose as a sole carbon source in a lab-scale anaerobic-oxic-anoxic (A₂O) SBR. In the SBR, due to the effect of incomplete denitrification and pH drop, the nitrogen and phosphorus removal efficiency decreased from 77% to 33.3% when the influent ammonium concentration increased from 20 mg/l to 80 mg/l. However, in the SBBR, simultaneous nitrification/denitrification (SND) occurred, and the nitrification rate in the aerobic phase did not change remarkably in spite of the increase in influent ammonium concentration. Phosphorus removal was not affected by the increase of influent ammonium concentration.     

Modelling of simultaneous methanogenesis and denitrification in an upflow packed-bed biofilm reactor

The performance of an upflow packed-bed biofilm reactor was investigated by considering simultaneous methanogenesis and denitrification reactions under step and sinusoidal variations of feed concentration and temperature. For simultaneous step inputs of 20 mg dm⁻³ of NO₃⁻—N and 60 mg dm⁻³ of methanol, the proposed model shows that major conversion of both the substrates takes place in the first half of the reactor. However, when the inlet concentration of methanol is subjected to sinusoidal variation, while that of NO₃⁻—N is maintained stepwise, the exit concentration of both methanol and NO₃⁻—N follow a sinusoidal response. On the other hand, when the inputs are reversed (methanol stepwise and NO₃⁻—N sinusoidal), the response exhibits similar behaviour. For sinusoidal variation of feed temperature the exit concentration profiles of both substrates also follow a sinusoidal pattern. For methanol, the mean steady state conversion under sinusoidal variation is higher than the corresponding steady state concentration when feed temperature is constant at 30°C. The model predictions are in good agreement with the experimental data available in the literature. ©1997 SCI     

高氮豆制品废水的亚硝酸型同步硝化反硝化生物脱氮工艺

采用序批式活性污泥法,通过控制溶解氧浓度开发出处理高氮豆制品废水的新工艺.实验结果显示,当曝气阶段反应器内溶解氧浓度保持在0.5 mg•L^-1左右时,曝气过程中NO^-₂-N/NO^-_x-N的比率始终维持在93%以上,并且曝气结束时,有大约87.6%的氨氮是通过同步硝化反硝化途径去除的.因此,控制反应器内溶解氧浓度在0.5 mg•L^-1左右时,在一个反应器内同时实现了亚硝酸型硝化反硝化和同步硝化反硝化.经过理论计算和机理分析,在此溶解氧下,亚硝酸菌的比增殖速率近似为硝酸菌的2.22～2.43倍,并且低溶解氧容易在活性污泥颗粒内形成进行反硝化作用的缺氧区.因此,在常温下,只要采用溶解氧传感器控制SBR反应器内溶解氧浓度在0.5 mg•L^-1左右,就可以实现稳定的亚硝酸型同步硝化反硝化生物脱氮工艺.     

Parametric study of the factors influencing simultaneous denitrification and enhanced biological phosphorus removal

In this study, the effect of various factors such as C:N ratio, carbon source, percentage P content in the sludge influencing the simultaneous denitrification and enhanced biological phosphorus removal was investigated in batch tests on bean and tomato waste sludge from an upflow anaerobic sludge blanket reactor–anoxic/aerobic system and municipal sludge from a circulating fluidized bed bioreactor. A correlation between the change in redox potential and rate of P release was developed. Interestingly, maximum P release was observed at positive redox potential in some of the batch tests. Simultaneous denitrification and P release under anoxic conditions was observed during all the batch tests. Sludge acclimatization improved the efficiency of the sludge and proved independency of maximum specific denitrification rate and P content of sludges. The contribution of denitrifying PAOs to anoxic P uptake was determined through the denitrification control test at an initial level of PO₄‐P of 100–120 mg dm^?3. Copyright © 2006 Society of Chemical Industry