Difficulties in maintaining long-term partial nitritation of ammonium-rich sludge digester liquids in a moving-bed biofilm reactor (MBBR).

Nitrogen can be eliminated effectively from sludge digester effluents by anaerobic ammonium oxidation (anammox), but 55-60% of the ammonium must first be oxidized to nitrite. Although a continuous flow stirred tank reactor (CSTR) with suspended biomass could be used, its hydraulic dilution rate is limited to 0.8-1 d(-1) (30 degrees C). Higher specific nitrite production rates can be achieved by sludge retention, as shown here for a moving-bed biofilm reactor (MBBR) with Kaldnes carriers on laboratory and pilot scales. The maximum nitrite production rate amounted to 2.7 gNO2-Nm(-2)d(-1) (3 gO2m(-3)d(-1), 30.5 degrees C), thus doubling the dilution rate compared to CSTR operation with suspended biomass for a supernatant with 700 gNH4-Nm(-3). Whenever the available alkalinity was fully consumed, an optimal amount of nitrite was produced. However, a significant amount of nitrate was produced after 11 months of operation, making the effluent unsuitable for anaerobic ammonium oxidation. Because the sludge retention time (SRT) is relatively long in biofilm systems, slow growth of nitrite oxidizers occurs. None of the selection criteria applied - a high ammonium loading rate, high free ammonia or low oxygen concentration - led to selective suppression of nitrite oxidation. A CSTR or SBR with suspended biomass is consequently recommended for full-scale operation.     

Optimizing and modelling nitrogen removal in a new configuration of the moving-bed biofilm reactor process.

A new configuration of the moving-bed biofilm reactor process with pre-denitrification and nitrification was investigated in a pilot plant, which is fed with urban raw wastewater, the primary settler is located between the anoxic and the aerobic reactors, and primary sludge is recycled to the anoxic reactor as a hybrid pre-denitrification. The carriers used in the experiments are made of high-density polyethylene, with a diameter of 10 mm and a specific surface area of 400 m(2)/m(3). The new process was compared with conventional pre-denitrification-nitrification using in-series reactors fed with settled wastewater. The new configuration achieved an increase of 45% for the denitrification rate and of 30% for the nitrification rate when compared with conventional configuration. These results were analysed in light of the calibration study of the mixed-culture biofilm (MCB) model and simulations in AQUASIM 2.1 platform. Regarding denitrification, the high values obtained in the new configuration were attributed to a higher removal of the slowly biodegradable substrate (Xs) in the anoxic reactor due to the use of raw wastewater and sludge recycle. Accordingly, the amounts of heterotrophic biomass (XH) and Xs obtained in simulations were higher in both the biofilm and the bulk liquid. Regarding nitrification, the higher values were attributed to a lower removal of Xs in the aerobic reactors and accordingly, a lower accumulation of heterotrophic biomass in the biofilm was found in the simulations.     

MBBR处理三河市城市污水的工程应用

采用移动床生物膜反应器(MBBR)处理三河市城市污水,实践证明,在填料填充率为30%(体积比),水力停留时间6.5h的条件下,反应器运行稳定且处理效果良好。系统稳定运行时,出水CODCr、BOD5、SS去除率分别为80.7%、84.2%、88.9%,达到《城镇污水处理厂污染物排放标准》(GB18918—2002)二级标准。     

MBBR工艺在制药废水中的应用

某制药厂提标改造工程将原有活性污泥生物系统升级改造为移动床生物膜反应器(MB-BR),在生化池内投加好氧活性生物填料.改造后,平均出水COD 78 mg/L,氨氮3.3 mg/L,总氮70.8 mg/L,各项指标好于当地的纳管标准.分别对系统活性污泥及生物膜进行菌群结构分析,发现活性污泥及生物膜系统内丰度较高的功能菌分...     

UNITANK工艺深度处理漂染废水

介绍UNITANK工艺深度处理漂染废水的效果,并探讨UNITANK工艺运行规律、HRT及水质变化等对处理效果的影响.结果表明,在中等有机负荷下,HRT 6 h,中间池DO为1.5～2 mg/L、边池DO为2 mg/L的条件下,处理效果较佳且稳定.经济方面也具有一定优势.     

Influence of surface modification of polyethylene biocarriers on biofilm properties and wastewater treatment efficiency in moving-bed biofilm reactors

Two methods of surface modification of polyethylene biocarriers, chemical oxidation-surface covering with ferric ion (CO-SCFe) and chemical oxidation-surface grafting with gelatin (CO-SGG), were studied for improving the efficiency of wastewater treatment by moving-bed biofilm reactors. The results showed that two surface modifications caused corrosion pits to increase surface roughness, and brought -(C=O)-/-O-C-O- groups and ferric ions to the biocarrier surface, respectively. The positively charged surface increased the hydrophilicity and biological affinity of the biocarrier. The biofilm formation rate was improved by 37.5 and 60% after surface modifications of CO-SCFe and CO-SGG; the concentration of biomass on the biocarriers was improved by 54.8 and 76.1% and the COD removal efficiencies were increased by 10.63 and 8.64%, respectively. Polymerase chain reaction-denaturing gradient gel electrophoresis analysis showed that the microbial populations in the biofilm were almost the same after surface modifications, but the biomass concentration was greatly increased.     

High-rate wastewater treatment combining a moving bed biofilm reactor and enhanced particle separation.

Many cities around the world are looking for compact wastewater treatment alternatives since space for treatment plants is becoming scarce. In this paper development of a new compact, high-rate treatment concept with results from experiments in lab-scale and pilot-scale are presented. The idea behind the treatment concept is that coagulation/floc separation may be used to separate suspended and colloidal matter (resulting in > 70% organic matter removal in normal wastewater) while a high-rate biofilm process (based on Moving Bed biofilm reactors) may be used for removing low molecular weight, easily biodegradable, soluble organic matter. By using flotation for floc/biomass separation, the total residence time for a plant according to this concept will normally be < 1 hour. A cationic polymer combined with iron is used as coagulant at low dosages (i.e. 1-2 mg polymer/l, 5-10 mg Fe/l) resulting in low sludge production (compared to conventional chemical treatment) and sufficient P-removal.     

改进型移动床生物膜反应器处理有机废水的试验

改进型移动床生物膜反应器(CMCBR)是在普通移动床生物膜反应器中引入导流板,使填料在全池循环移动,消除了普通移动床生物膜反应器的死角。在CMCBR处理模拟生活污水的试验中,研究了有机物的去除效果,考察了容积负荷、水力停留时间、冲击负荷等参数对处理效果的影响。试验发现,在填料填充比例为50%(体积比),进水COD质量浓度为320~550mg/L,水力停留时间为3 h的条件下,出水COD质量浓度小于100 mg/L,达到国家污水综合排放标准的一级标准。反应器具有较强的抗冲击负荷能力,出水水质稳定。     

混凝沉淀-ABR-接触氧化工艺处理纱线染整废水

采用混凝沉淀—ABR—接触氧化工艺处理纱线染整废水,并对工艺单元的特点和运行情况进行了分析。运行结果表明,混凝沉淀池对CODCr和色度的去除率分别为50.5%和76.9%;ABR和接触氧化池的容积负荷分别为0.73kgCODCr/(m3.d)和0.43kgCODCr/(m3.d);处理后出水CODCr<85.5mg/L,色度<40倍,系统对CODCr、BOD5、SS、色度和硫化物的平均去除率分别为89.8%、92.1%、82.8%、95.2%和99.2%。     

污水处理厂尾水再生回用于印染工艺用水的应用实践

为保证印染工艺用水系统安全经济运行,工业园区新建再生水回用工程.工程利用高密市第一城市生活污水处理厂尾水,根据印染工业用水要求确定回用水质标准,优选采用混合絮凝沉淀—臭氧活性炭—超滤—反渗透—消毒工艺,对污水处理厂排放尾水进行深度处理,处理后的尾水作为园区企业印染工艺生产用水.产水量为12 000 m3/d,总产水率约60％.该系统建设完成运行1年,出水水质能稳定达到工业回用水质标准,可以满足孚日工业园区新增工业项目用水需求.本项目总投资为10 723.73万元,单位经营成本为2.37元/m3,单位制水成本约为4.07元/m3,是城市污水再生利用、解决工业用水资源短缺问题的应用实践.     

Tracking particle size distributions in a moving bed biofilm membrane reactor for treatment of municipal wastewater.

A study has been conducted to investigate the effect of loading rates on membrane fouling in a moving bed biofilm membrane reactor process for municipal wastewater treatment, especially analysing the fate of submicron colloidal particles and their influence on membrane fouling. Two operating conditions defined as low and high organic loading rates were tested where the development and fate of the particulate material was characterised analysing the particle size distributions throughout the process. Analysis of the membrane performance showed higher fouling rates for the high-rate conditions. The fraction of colloidal submicron particles was higher in the membrane reactor indicating that fouling by these particles was a dominant contribution to membrane fouling.     

A one-stage system with partial nitritation and anammox processes in the moving-bed biofilm reactor.

The ability of bacterial cultures to create biofilm brings a possibility to enhance biological wastewater treatment efficiency. Moreover, the ability of Anammox and Nitrosomonas species to grow within the same biofilm layer enabled a one-stage system for nitrogen removal to be designed. Such a system, with Kaldnes rings as carriers for biofilm growth, was tested in a technical pilot plant scale (2.1 m(3)) at the Himmerfj?rden Waste Water Treatment Plant (WWTP) in the Stockholm region. The system was directly supplied with supernatant originating from dewatering of digested sludge containing high ammonium concentrations. Nearly 1-year of operational data showed that during the partial nitritation/Anammox process, alkalinity was utilised parallel to ammonium removal. The process resulted in a small pH drop, and its relationship with conductivity was found. The nitrogen removal rate for the whole period oscillated around 1.5g N m(-2)d(-1) with a maximum value equal to 1.9 g N m(-2)d(-1). Parallel to the pilot plant experiment, a series of batch tests were run to investigate the influence on removal rates of different dissolved oxygen conditions and addition of nitrite. The highest nitrogen removal rate (5.2g N m(-2)2d(-1)) in batch tests was obtained when the Anammox process was stimulated by the addition of nitrite. In the simultaneous partial nitritation and Anammox process, the partial nitritation was the rate-limiting step.     

Application of chemical precipitation for piggery wastewater treatment.

Several series of experiments were conducted to investigate the treatment of piggery wastewater using chemical precipitation (CP) where various types of coagulants such as aluminium sulfate (Al2(SO4)3), poly aluminium chloride (PAC), ferric chloride (FeCl3), ferric sulfate (Fe2(SO4)3), ferrous sulfate (FeSO4) and ferrous chloride (FeCl2) were used. Throughout the experiments, CP was found to achieve high removal efficiencies for organic compounds and nutrients (nitrogen and phosphorus) from the piggery wastewater. Experimental results showed the optimal doses of FeCl3, Fe2(SO4)3, FeCl2 and FeSO4 was 2.0 g/L, while 0.31 g/L and 2.5 g/L were the optimum dose for PAC and Al2(SO4)3, respectively. The pH range 4-5 resulted in the best performance to all coagulants except FeCl2 and FeSO4, whose optimum pH were more than 6. Percentage removal efficiencies for COD were in the ranges of 70-80%, 90-95% for SS, 80-90% for organic-N and TP. Those removal efficiencies were achieved within 5 min of operation. Three times of repetition in CP resulted in higher removal efficiencies for COD, SS and colour up to 74%, 99% and 94% respectively, in which Al2(SO4)3 was used as the coagulant. Removal efficiencies of various water quality parameters in a continuously operated reactor were similar to those of the batch experiments. Biodegradable ratios (BOD5/COD) increased up to 65% after the application of CP.     

Aerobic granulation in a sequencing batch reactor (SBR) for industrial wastewater treatment.

Aerobic granulation seems to be an a attractive process for COD removal from industrial wastewater, characterised by a high content of soluble organic compounds. In order to evaluate the practical aspects of the process, comparative experimental tests are performed on synthetic and on industrial wastewater, originating from pharmaceutical industry. Two pilot plants are operated as sequencing batch bubble columns. Focus was put on the feasibility of the process for high COD removal and on its operational procedure. For both wastewaters, a rapid formation of aerobic granules is observed along with a high COD removal rate. Granule characteristics are quite similar with respect to the two types of wastewater. It seems that filamentous bacteria are part of the granule structure and that phosphorus precipitation can play an important role in granule formation. For both wastewaters similar removal performances for dissolved biodegradable COD are observed (> 95%). However, a relatively high concentration of suspended solids in the outlet deteriorates the performance with regard to total COD removal. Biomass detachment seems to play a non-negligible role in the current set-up. After a stable operational phase the variation of the pharmaceutical wastewater caused a destabilisation and loss of the granules, despite the control for balanced nutrient supply. The first results with real industrial wastewater demonstrate the feasibility of this innovative process. However, special attention has to be paid to the critical aspects such as granule stability as well as the economic competitiveness, which both will need further investigation and evaluation.     

Evaluating a strategy for maintaining nitrifier activity during long-term starvation in a moving bed biofilm reactor (MBBR) treating reverse osmosis concentrate

A two-stage moving bed biofilm reactor (MBBR) was applied at the Bundamba advanced water treatment plant (AWTP) (Queensland, Australia) to treat the reverse osmosis concentrate (ROC) for inorganic nutrient removal. One of the operational challenges for the system was to cope with the large fluctuations of the ROC flow. This study investigated the decay rates of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) and biofilm detachment in MBBR during starvation for up to one month. An intermittent aeration strategy of 15 min aeration every 6 h was applied. This study also evaluated the activity recovery of both AOB and NOB after normal operation was resumed. The results showed that the activity loss of AOB and NOB was relatively minor (<20%) within 10 days of starvation, which ensured relatively quick recovery of ammonium removal when normal operation resumed. In contrast, the AOB and NOB activity loss reached 60-80% when the starvation time was longer than 20 days, resulting in slower recovery of ammonium removal after starvation. Starvation for less than 20 days didn't result in an apparent biomass detachment from carriers.     

接触氧化-强化混凝法处理低温城镇污水

试验主要研究了低温条件下,接触氧化-强化混凝联合工艺对城镇污水的处理效果.结果表明;当进水平均温度低于12 ℃,CODCr 130～320 mg/L,氨氮20～45 mg/L,TP 2～4.5 mg/L时,其去除率分别可达到88%、70%、95%,出水可达到《城镇污水处理厂污染物排放标准》(GB18918-2002)一级B标准.强化混凝工艺能有效改善低温对接触氧化工艺造成的影响.     

Innovations in wastewater treatment: the moving bed biofilm process.

This paper describes the moving bed biofilm reactor (MBBR) and presents applications of wastewater treatment processes in which this reactor is used. The MBBR processes have been extensively used for BOD/COD-removal, as well as for nitrification and denitrification in municipal and industrial wastewater treatment. This paper focuses on the municipal applications. The most frequent process combinations are presented and discussed. Basic design data obtained through research, as well as data from practical operation of various plants, are presented. It is demonstrated that the MBBR may be used in an extremely compact high-rate process (<1 h total HRT) for secondary treatment. Most European plants require P-removal and performance data from plants combining MBBR and chemical precipitation is presented. Likewise, data from plants in Italy and Switzerland that are implementing nitrification in addition to secondary treatment are presented. The results from three Norwegian plants that are using the so-called combined denitrification MBBR process are discussed. Nitrification rates as high as 1.2 g NH4-N/m2 d at complete nitrification were demonstrated in practical operation at low temperatures (11 degrees C), while denitrification rates were as high as 3.5g NO3-Nequiv./m2.d. Depending on the extent of pretreatment, the total HRT of the MBBR for N-removal will be in the range of 3 to 5 h.     

Assessment of electrochemical and chemical coagulation as post-treatment for the effluents of a UASB reactor treating cellulose pulp mill wastewater.

This paper presents results from exploratory experiments to test the technical feasibility of electrolytic treatment and coagulation followed by flocculation and sedimentation as post-treatment for the effluent of an UASB reactor treating simulated wastewater from an unbleached Kraft pulp mill. The electrolytic treatment provided up to 67% removal of the remaining COD and 98% of color removal. To achieve these efficiencies the energy consumption ranged from 14 Wh x l(-1) to 20 Wh x l(-1). The coagulation-flocculation treatment followed by settling required 350-400 mg x l(-1) of aluminium sulfate. The addition of a high molecular weight cationic polymer enhanced both COD and color removal. Both post-treatment processes are technically feasible.     

A pilot-plant study of a moving-bed biofilm reactor system using PVA gel as a biocarrier for removals of organic carbon and nitrogen.

A pilot-plant study was conducted to evaluate the performance of a moving-bed biofilm reactor process using PVA-gel beads as a biocarrier. Real primary-settled wastewater was fed to the pre-denitrification system and removals of nitrogenous and organic contaminants were evaluated over a 1-year period. The results demonstrated that at a total nitrogen (TN) loading of 18 mg/L.h, a TN removal efficiency in keeping with and even exceeding the theoretical maximum efficiency based on the level of internal recycle, was possible and a nitrification rate of 15 mg/L.h was sustained with a HRT of only 2.5 h at 15 degrees C. Furthermore, soluble COD and BOD5 in the effluent of the pilot plant were reduced to levels well below most regulatory discharge limits. In addition, the possibility of using this biocarrier in a system, including the elimination of waste organic sludge, was discussed.