The Kinetics for Electrochemical Removal of Ammonia in Coking Wastewater

Electrochemical removal of ammonia is a new and effective method in coking wastewater.The reaction mechanism of ammonia removal was proved by stable polarization curve in this paper.First,the supposing of reaction steps of the electrode were proposed.And then reaction parameter of the electrode was measured by Tafel curve.Finally,the reaction mechanism was determined by quasi-equilibrium approach.The results showed that Cl2+H2O→HOCl+H++Cl was the rate-determining step,the calculated apparent transfer coefficient was uniform to the experimental value.

Influence of osmotic distillation on membrane absorption for the treatment of high strength ammonia wastewater

Osmotic distillation(OD) was found to be a coupled process in membrane absorption(MA) for the treatment of high strength ammonia wastewater. As a result, ammonia could not be concentrated in absorption solution(AS) as expected. The inhibition of the coupled OD in MA process was investigated as well as various factors affecting the inhibition. The results indicated that the coupled OD can be effectively inhibited by heating concentrated solution and cooling dilute solution. It was also found that experimental minimum inhibition temperature difference(MITD) between concentrated and dilute solutions was different when using polyvinylidene fluoride(PVDF) and polypropylene(PP) membranes respectively, which could be ascribed to material properties, such as OD and membrane distillation(MD) coefficients of the membranes. Experimental MITDs were found to be higher than theoretical MITDs which were calculated using a simplified method.

Effects of Coagulation and Ozonation Pretreatments on Biochemical Treatment of Fluid Catalytic Cracking Wastewater

Fluid catalytic cracking (FCC) salty wastewaters, containing quaternary ammonium compounds (QACs), are very difficult to treat by biochemical process. Anoxic/oxic (A/O) biochemical system, based on nitrification and denitrification reactions, was used to assess their possible biodegradation. Because of the negative effects of high salt concentration (3%), heavy metals and toxic organic matter on microorganisms’ activities, some techniques consisting of dilution, coagulation and flocculation, and ozonation pretreatments, were gradually tested to evaluate chemical oxygen demand (COD), ammonia-nitrogen (ammonia-N) and total nitrogen (TN) removal rates. In this process of FCC wastewater, starting with university-domesticated sludge, the ammonia-N and TN removal rates were worst. However, when using domesticated SBR’s sludge and operating with five-fold daily diluted influent (thus reducing salt concentration), the ammonia-N removal reached about 57% while the TN removal rate was less than 37% meaning an amelioration of the nitrification process. However, by reducing the dilution factors, these results were inflected after some days of operation, with ammonia-N removal decreasing and TN barely removed meaning a poor nitrification. Even by reducing heavy metals concentration with coagulation/flocculation process, the results never changed. Thereafter, by using ozonation pre-treatment to degrade the detected organic matter of di-tert-butylphenol and certain isoparaffins, COD, ammonia-N and TN removal rates reached 92%, 62% and 61%, respectively. These results showed that the activities of the microorganisms were increased, thus indicating a net denitrification and nitrification reactions improvement.

Community analysis of ammonia-oxidizing bacteria in activated sludge of eight wastewater treatment systems

We investigated the communities of ammonia-oxidizing bacteria （AOB） in activated sludge collected from eight wastewater treatment systems using polymerase chain reaction （PCR） followed by terminal restriction fragment length polymorphism （T-RFLP）, cloning, and sequencing of the α-subunit of the ammonia monooxygenase gene （amoA）. The T-RFLP fingerprint analyses showed that different wastewater treatment systems harbored distinct AOB communities. However, there was no remarkable difference among the AOB T- RFLP profiles from different parts of the same system. The T-RFLP fingerprints showed that a full-scale wastewater treatment plant （WWTP） contained a larger number of dominant AOB species than a pilot-scale reactor. The source of influent affected the AOB community, and the WWTPs treating domestic wastewater contained a higher AOB diversity than those receiving mixed domestic and industrial wastewater. However, the AOB community structure was little affected by the treatment process in this study. Phylogenetic analysis of the cloned amoA genes clearly indicated that all the dominant AOB in the systems was closely related to Nitrosomonas spp. not to Nitrosospira spp. Members of the Nitrosomonas oligotropha and Nitrosomonas communis clusters were found in all samples, while members of Nitrosomonas europaea cluster occurred in some systems.

Study on Influencing Factors and Kinetics of Removal of Ammonia Nitrogen from High Salinity Wastewater by Sodium Hypochlorite Oxidation

The influencing factors and kinetics of oxidative degradation of ammonia nitrogen in high salinity wastewater by sodium hypochlorite oxidation( Na Cl O) were studied. The results showed that the degradation process of ammonia nitrogen by sodium hypochlorite accorded with a pseudo first-order kinetics model,and the influencing factors included Na Cl O dosage,initial concentration of ammonia nitrogen,salinity,temperature,and so on. When Na Cl O dosage was 0. 6%( MCl∶ MN= 13. 76),the reaction rate constant was up to 0. 015 75 min^(-1). The higher the initial concentration of ammonia nitrogen was,the worse the effect of oxidation reaction was. When the initial concentration did not exceed 45 mg/L,the effect on oxidation reaction rate constant increased with the increase of the initial concentration. Low salinity had no effect on ammonia nitrogen oxidation.When salinity was higher than 2. 0%,the inhibition effect on ammonia nitrogen oxidation would increase,and the reaction rate constant decreased obviously with the increase of salinity. The improvement of reaction temperature was beneficial to ammonia oxidation degradation. As temperature increased from 10 to 35 ℃,the reaction rate constant rose from 0. 00188 to 0. 01043 min^(-1).

Isolation and Identification of Ammonia Nitrogen Degradation Strains from Industrial Wastewater

Nine strains of ammonia nitrogen degradation strains from C1 to C9 were isolated from industrial wastewater to study their degradation and conversion of ammonia nitrogen. The results showed that C2 strain with a high degradation activiity of ammonia nitrogen, and the ammonia nitrogen degradation rate of the activated C2 strain was 93% within 24 h when the initial concentration of ammonia nitrogen was 200 mg/L under the conditions of inoculation 10%, temperature 35?C, pH 7.0, rotation 200 r/min. And C2 was identified as Bacillus amyloliquefaciens.

Treatment of nickel-ammonia complex ion-containing ammonia nitrogen wastewater

Air stripping was adopted to treat nickel ammonia complex ion-containing wastewater in order to remove nickel and ammonia simultaneously in one technological process.The relationship among pH,the concentration of nickel ammonia complex ion and total ammonia concentration was analyzed theoretically.Influence of pH value,water temperature,airflow rate and time on air stripping was studied in detail by static experiment in laboratory.The results show that at pH 11,temperature of 60℃and airflow rate of 0.12 m3/h,NH3 and Ni 2+concentrations remained in wastewater are less than 2 and 0.2 mg/L,respectively,after blowing for 75 min,which reaches the standard of the state discharge.When the tail gas is absorbed by 0.5 mol/L H2SO4 in order to avoid the secondary pollution,the absorption rate can achieve 70%.

Removal of organic matter and nitrogen from distillery wastewater by a combination of methane fermentation and denitrification/nitrification processes

The distillery wastewater of Guangdong Jiujiang Distillery, which is characteristic of containing high organic matters and rich total nitrogen, was treated by a combination of methane fermentation and denitrification/nitrification processes. 80% of COD in the raw wastewater was removed by methane fermentation at the COD volumetric loading rate of 20 kg COD/（m^3·d） using the expanded granule sludge bed （EGSB） process. However, almost all the organic nitrogen in the raw wastewater was converted into ammonia by ammonification there. Ammonia and volatile fatty acids （VFA） remaining in the anaerobically treated wastewater were simultaneously removed utilizing VFA as an electron donor by denitrification occurring in the other EGSB reactor and nitrification using PEG-immobilized nitrifying bacteria with recirculation process. An aerobic biological contact oxidization reactor was designed between denitrification/nitrification reactor for further COD removal. With the above treatment system, 18000-28000 mg/L of COD in raw wastewater was reduced to less than 100 mg/L. Also, ammonia in the effluent of the system was not detected and the system had a high removal rate for 900-1200 mg/L of TN in the raw wastewater, only leaving 400 mg/L of nitrate nitrogen.

Treatment of coke plant wastewater by SND fixed biofilm hybrid system

In this article, coke plant wastewater was treated by a simultaneous nitrifying and denitrifying （SND） fixed biofilm hybrid system. The results showed that suitable parameters of the system were important for the performance of the bio-degradation system. The chemical oxygen demand （COD） removal efficiency in this system was satisfactory, higher than 94%, and ammonia nitrogen was higher than 95%. The effluent COD concentration could meet the discharge standard, except for very few situations. The results showed that a sufficient carbon source was important for making ammonia nitrogen concentration meet the discharge standard. Then the TiN removal efficiency in this system can be brought higher than 94%. Dissolved oxygen （DO） is very important to the performance of the SND bio-degradation system, and the suitable DO is about 3.5-4.0 mg/L at the forepart of reactor. In addition, the performance of the system was almost not affected by pH value. The results show that the system is feasible to treat coke plant wastewater.

Seed yeast cultivation for salad oil manufacturing wastewater treatment

The mixture of five yeast strains obtained from soil could remove about 85% TOC of oil rich wastewater in batch test. While the highest MLSS was obtained at an N∶C of 1∶5, the oil removal decreased with the increase of N∶C during yeast sludge cultivation. Ammonium chloride was the best nitrogen source for yeast cultivation from the viewpoint of yeast growth and oil utilization. An ammonia concentration of over 1300 mg/L led to mass death of yeast at a pH of 5. The ammonia concentration should be controlled at a level of 1000 mg/L or lower.

Experimental Research on Coke Wastewater Treatment by Hybrid Biological Reactor

Phase hybrid biological reactor (HBR) was used in treating coke wastewater by adding submerging fiber-ball fillers in suspended growth activated sludge.The optimum operation parameters for the highest performance were determined.It was found that the hybrid biological reactor worked well for the coke wastewater treatment in terms of Chemical Oxygen Demand (COD),NH+4-N and other refractory organic compounds removal efficiencies.Compared with conventional activated sludge system,the removal rate of COD and NH+4-N and the nitrating rate were higher and more stable in the hybrid biological reactor.COD of effluent was less than 75 mg/L and the removal rate of COD and NH+4-N could be up to 95.0% and 92.5% when COD of influent and NH+4-N were less than 700 mg/L and 300 mg/L,respectively.In this way,the quality of effluent concentration could reach the first class of integrated wastewater discharge standard (GB8978-1996)(COD ≤100 mg/L).

Reclaimation of petroleum-based wastewater by noval ozone immobilized biological activated carbon process

Wastewater reclamation in the petroleum industries in Northern China is important because of the shortage of water resource. Conventional treatment technology used in treating petroleum-based wastewater, namely the 3-phase biological process, typically removes COD, BOD, grease, volatile hydrobenzenes, cyanides, sulfides and suspended solids. However, the process is often ineffective in ammonia-nitrogen removal, and thus the treated effluent quantity can’t meet the required standards for reuse. This paper investigated a novel ozone immobilized biological activated carbon （O3-IBAC） process for ammonia nitrogen removal from petroleum-based wastewater. Operated at a HRT （Hydraulic Retention Time） of 15 minutes in IBAC1 and 27 minutes in IBAC2, the O3-IBAC process achieved ammonia nitrogen removal efficiency of 91%. In addition, the removal efficiencies of COD, volatile hydrobenzenes, suspended solids, turbidity and petroleum-based micro-pollutants were all above 90%. Competition between the autotrophs and heterotrophs was observed, which was indicated by an increase of ammonia nitrogen removal with a decrease of COD removal, and vise versa. Nitrite accumulation in IBAC1 followed by erobic shortcut denitrification in IBAC2 led to 28% of the Total Nitrogen removal efficiency. Pollutant reduction in the IBAC process was achieved by a rapid physical adsorption and biodegradation on the activated carbon, which effectively retained the pollutants in the system despite the short hydraulic retention time.

Biodegradation of Ammonia Nitrogen Using a Novel Candida sp. Strain N6 Immobilization

Due to the high efficiency of ammonia nitrogen degradation,a novel Candida sp.strain N6 was applied for wastewater treatment by using immobilization technology.Immobilization conditions and corresponding ammonia removal capacity of immobilized N6 beads were investigated.The immobilized N6 beads were applied to degrade simulated ammonia nitrogen wastewater.Results showed that the optimum formula of immobilized materials was 9%polyvinyl alcohol,1.5%sodium alginate,and 2%calcium chloride,under which the ammonia nitrogen removal rate of the immobilized N6 beads reached 97.97%.The following immobilization conditions were observed to be optimal:the immobilization time was 24 h,the inoculum of N6 was 3%,and the pH was 8.The immobilized N6 beads exhibited excellent ammonianitrogen degradation ability in SBRs.The ammonia nitrogen removal rate was stable at 95%-99%in the SBRs.The results indicated that immobilized N6 beads possess good application prospects in the treatment of ammonia nitrogen wastewater.

鸟粪石沉淀法处理高浓度氮磷废水研究进展

随着节能低碳理念的深入发展,鸟粪石沉淀法因其较高的氮磷回收效率和相对低能耗的优势,近年来成为高浓度氮磷废水处理和资源化利用的热点方向之一。系统地对国内外鸟粪石沉淀法处理污水的相关文献进行了梳理,从新兴处理对象及方案、回收反应器构型开发、低成本镁源开发、高效结晶、晶体分离提纯等方面,总结了相关研究成果。此外,结合环境毒理性、处理成本、综合资源化利用等角度对鸟粪石沉淀法的发展前景和趋势进行预判,为相关研究提供参考。

低氨氮质量浓度废水DPR-SNAD脱氮除磷效能研究

针对低氨氮废水单级自养脱氮系统副产物硝氮残留,有机物耐受能力差,以及缺乏除磷功能等问题,提出反硝化除磷(Denitrifying Phosphorus Removal,DPR)-单级自养脱氮(Simultaneous Partial Nitrification,Anaerobic Ammonium Oxidation and Denitrification,SNAD)组合处理技术,重点考察氨氮负荷对单级自养脱氮工艺(Single-stage Nitrogen Removal Using Anammox And Partial Nitritation,SNAP)系统、泥龄对DPR系统构建的影响,以及低氨氮废水DPR-SNAD组合处理系统的脱氮除磷效能与微生物种群。研究结果显示:采用氨氮质量浓度梯度递减方式,氨氮负荷为0.20 kg N/(m^(3)·d)的低氨氮质量浓度的SNAP系统构建时间为63 d,较负荷为0.05 kg N/(m^(3)·d)的系统缩短了37 d。泥龄对构建的DPR系统效能影响显著,泥龄为35 d的系统除磷脱氮效能较高,PO_(4)^(3-)-P、NO_(3)^(-)-N、COD去除率分别为86.25%、98.00%、92.00%,系统释磷、吸磷、反硝化脱氮速率分别达4.60 mg/(L·h)、4.13 mg/(L·h)、5.53 mg/(L·h)。DPR-SNAD组合处理系统的氨氮(NH_(4)^(+)-N)、总氮(Total Nitrogen,TN)、总磷(Total Phosphorus,TP)、化学需氧量(Chemical Oxygen Demand,COD)去除率分别为100%、98.64%、86.00%、93.30%。TN、TP去除率较对照组SNAP分别提高了19.20百分点和86.00百分点。16S rRNA高通量测序结果显示,组合系统脱氮除磷功能菌属主要有Rhodobacter、Candidatus_Brocadia、Nitrosomonas、Gemmobacter,SNAD系统中厌氧氨氧化菌(Anaerobic Ammonia Oxidation,AnAOB)相对丰度显著高于对照组SNAP系统,DPR促进SNAD提高了系统脱氮效能。

正渗透膜回收废水中氨氮的研究进展

综述了正渗透(FO)膜技术对废水中的氨氮回收的研究进展。重点介绍了其发展历史、工艺原理、应用现状,将应用现状分为膜制造和改性、膜与其它工艺的耦合工艺、提取液、膜污染、数学建模这五方面进行了综述。在此基础上,对正渗透膜技术的研究前景进行了展望。

生物增效技术促进炼油废水降氮效果分析

介绍了针对外排氨氮标准不断提升,炼油含盐废水处理装置出水氨氮控制难度增加,在一段时期常出现波动情况,投加硝化菌进行生物增效处理达标的生产试验。对试验过程和试验前后含盐污水处理装置进、出水数据进行分析,对照出水pH值与硝化系统的关系,找到了出水氨氮异常升高主要是污水处理系统碱度降低引起的根本原因。证明了投加硝化菌进行生物增效的方法可作为恢复污水生化系统快速建立硝化系统,恢复氨氮去除能力的有效应急手段。