Survey of MBR market: Trends and perspectives in China

Membrane bioreactor (MBR) has gained considerable attention for wastewater treatment and reuse in China in the last two decades. Comparing with the global MBR market, which has an average annual growth rate of 10.9%, the average annual growth rate in China is nearly 100% in recent years. In the past 10 years, publications on MBR researches and applications for wastewater treatment have increased sharply. Over three hundred MBR plants have been successfully applied into practice for different wastewater treatments, such as municipal wastewater, bathing wastewater, restaurant wastewater, landfill leachate, hospital wastewater, petrochemical wastewater and high-concentration industrial wastewater. These plants have capacities ranging from 10 to 100,000 m³/d, among which over 12 MBR plants have capacities exceeding 10,000 m³/d. The largest MBR plant, i.e. Beijing Kunyu River WWPT, which has a capacity of 100,000 m³/d for municipal wastewater treatment and reuse, was constructed in Beijing by Origin Water Technology Co., Ltd. The largest MBR plant for industrial wastewater treatment was located in Tianjin and installed by Motimo Membrane Inc., which has a capacity of 30,000 m³/d. The largest MBR application for industrial sectors was petrochemical wastewater treatment, and over ten MBR plants each exceed a capacity of 5000 m³/d. In South-east China, the constructed MBRs are mostly involved in the high-strength industrial wastewater treatment while in North China MBRs mainly focused on municipal wastewater treatment and reuse.For an MBR commercial application in China, MBR plants were constructed by a lot of home-grown companies such as Tianjin Motimo Membrane Technology Co., Ltd., Beijing Origin Water Technology Co., Ltd. and Omexell Environmental Engineering Co., Ltd. and overseas-funded companies like Zenon-GE and CNC-Simens. Origin Water occupies the majority of the MBR market in China, whereas CNC-Simens and Zenon-GE have a larger number of installations in other parts of China. MBR unit key suppliers in China are Zenon (Canada), Mitsubishi-Rayon (Japan), Toray (Japan), Kubota (Japan), Norit (Netherlands), Motimo (China) etc.Due to more stringent regulations and wastewater reuse strategies, it is expected that a significant increase in MBR plant capacity and a widening of application areas will occur in the future.     

Behavior of Membrane Scaling During Crossflow Filtration in the Anaerobic MBR System

Abstract

Fouling of membrane bioreactor (MBR) has been studied intensively. Because of the high concentration of carbonates, scaling can be a serious problem in anaerobic bioreactor, which attracts little attention. In this study, the wastewater was treated with an anaerobic process followed by either a submerged or a side‐stream aerobic membrane reactor. The wastewater was spiked with calcium to investigate the effect of scaling on membrane filtration. Very little scaling was detected in the external membrane system (the side‐stream MBR). Results from chemical cleaning of internal membrane system indicated that the flux decline caused by membrane scaling was far more severe than that by membrane fouling. However, the flux decline from membrane scaling can be effectively recovered by the chemical cleaning of EDTA and NaOCl.     

A novel combination of methane fermentation and MBR — Kubota Submerged Anaerobic Membrane Bioreactor process

Methane fermentation is considered one of the best placed biological processes to reduce volume of organic waste while keeping small sludge production and recovering energy. One of the disadvantages of early anaerobic digestion technologies was the long hydraulic retention time thus large capacity tanks were required to hold slow growing methanogenic bacteria. New technological attempts such as upflow anaerobic sludge blanket (UASB), fixed or fluidised bed and membrane bioreactor (MBR) appeared as countermeasures.Kubota’s submerged anaerobic membrane biological reactor (KSAMBR) process has been developed in the last decade and successfully applied in a number of full-scale food and beverage industries. It consists of a solubilization tank and a thermophilic digestion tank, the latter incorporating submerged membranes. The biogas generated can be utilized for water heating via boilers. Both permeate and waste anaerobic sludge are further treated in wastewater treatment facilities.One of the main advantages of KSAMBR is that membranes retain the methanogenic bacteria while dissolved methane fermentation inhibitors such as ammonia are filtered out with the permeate. This makes the KSAMBR process very stable. Furthermore, the digester volumes can be scaled down to 1/3 to 1/5 of the conventional digesters provided that biomass is 3 to 5 times as concentrated.Applications include stillage treatment plants for Shouchu (Japanese spirits made from sweet potato, rice or other grains), potato processing sites, sludge liquor and food factory treatment plants.In summary, it is believed that KSAMBR offers the best possible solution combining the benefits of methane fermentation process with the performance of membrane technology. More details will be presented in the proceedings paper and in the presentation.     

Application of MBR for hospital wastewater treatment in China

In China, the number of hospitals has increased to 19,712 in 2008, with the production of hospital wastewater reaching 1.29 × 10⁶ m³/d. Membrane bioreactor (MBR) technology presents a more efficient system at removing pathological microorganism compared with existing wastewater treatment systems. In the past 8 yr, over 50 MBR plants have been successfully built for hospital wastewater treatments, with the capacity ranging from 20 to 2000 m³/d. MBR can effectively save disinfectant consumption (chlorine addition can decrease to 1.0 mg/L), shorten the reaction time (approximately 1.5 min, 2.5-5% of conventional wastewater treatment process), and attain a good effect of inactivation of microorganism. Higher disinfection efficacy is achieved in MBR effluents at lower dose of disinfectant with less disinfection by-products (DBPs). Moreover, when capacity of MBR plants increases from 20 to 1000 m³/d, their operating cost decreases sharply.     

Structural Analysis and Dewatering Characteristics of Waste Sludge from WWTP MBR

Abstract

A pilot‐scale UF membrane bioreactor (MBR) of 1 m³/day capacity was set up in an industrial wastewater treatment plant to evaluate its performance. This study mainly focused on testing the dewaterability and structural analysis of MBR sludge. MBR had 14% reduction of excess sludge production in relative to the conventional activated sludge process (CAS sludge). For dewatering, MBR sludge had comparable dewaterability with the CAS sludge but required nearly 20% less flocculant to reach the highest filterability χ and lowest specific filtration resistance (SRF). This could reduce the cost for running the dewatering facilities and final disposal. Meanwhile the chemical and morphological analyses on MBR sludge exhibited lower EPS (exocellular polymeric substances) content, slightly smaller flocs and more compact morphology. Additionally, to estimate the appropriate polyelectrolyte dose prior to dewatering, we measured the hysteresis loop area of the sludge rheogram (shear stress vs. shear rate) using a co‐axial cylinder viscometer. For both sludges, the area dramatically increased at some critical flocculant dosage and then plateaued off. The critical dosage, though not optimal, still led to an acceptable dewatering performance for the sludge.     

Comparison of removal of pharmaceuticals in MBR and activated sludge systems

Membrane bioreactors (MBRs) nowadays attract serious attention for the treatment of municipal wastewater, due to recent technical innovations and drastic cost reductions of the employed membranes. Especially the high biomass concentrations and long sludge retention times are favorable for the biodegradation of organic pollutants, resulting in high rate treatment systems. These characteristic features of MBR technology are not merely advantageous for organic matter removal, but also likely promote a higher biodegradation efficiency of refractory organic pollutants. The increasing concern about the potential accumulation of micro-pollutants such as pesticides, pharmaceuticals and personal care products, in the aquatic environment triggered many investigations into their biological degradation or fate in wastewater treatment systems. In this work a short overview is presented on the current knowledge of removal of pharmaceuticals in MBRs compared to their removal in conventional activated sludge treatment system. In general, for slowly degradable pharmaceuticals the removal in MBRs is better due to the relatively long sludge ages, which leads to the development of distinct microbial communities in MBRs compared to activated sludge plants. Nevertheless, from the literature results it could not be concluded that pharmaceutical removal in MBR reactors is better as many other factors have been indicated that may affect biodegradation rates, which are not directly related to the reactor configuration.     

Engineering design approaches for minimum fouling in submerged MBR

A contributor to success in managing membrane operations is to be able to identify suitable engineering design approaches to slow down the membrane fouling rate. Two such approaches were discussed in this study, namely: (1) offsite chemical and mechanical cleaning, and (2) air scouring. A longer subsequent operation time was observed after a membrane was cleaned chemically compared with mechanically. For air scouring during membrane operation, the investigation aimed at determining the crossflow velocity induced by coarse and fine bubble diffusers. Higher crossflow velocities were obtained with the latter. Uniformly distributed fine air bubbling might possibly have caused less uplift resistance and induced higher crossflow velocities. Such air scouring, at critical aeration intensity, was able to prolong the membrane operation for up to 8 months without needing chemical or mechanical cleaning.     

MBR module design and operation

Membrane Bioreactor (MBR) technology is widely accepted today for wastewater treatment providing superior effluent quality, opportunities for water reuse, smaller footprint, and better process control. In the following paper, the development and application of hollow fibre submerged membrane modules in Membrane Bioreactors will be discussed. Early MBR systems used tubular cross flow micro-filtration (MF) or ultra-filtration (UF) membrane modules but the huge energy demand for cross flow technology limited it to heavily polluted niche applications. In the late 80’s the development of submerged membrane technology reduced the energy consumption by using aeration to induce a cross flow and withdrawing purified water by slight vacuum allowing the adoption of MBR technology to more conventional applications. Based upon the m² of membrane area sold/used worldwide, hollow fibre membrane technology is today the most successful submerged MBR technology.     

MBR工艺深度处理印刷电路板废水的研究

分别采用陶瓷膜和超滤膜生物反应器对某印刷电路板(PCB)厂现有废水处理厂出水进行深度处理研究。结果表明:在进水COD 191.2?270.4 mg/L,氨氮30?50 mg/L,MLSS 6 500 mg/L,DO 4?8 mg/L,反应时间为5 h的条件下,两种膜生物反应器出水COD和氨氮的浓度分别低于99.2 mg/L和0.759 mg/L,达到《污水综合排放标准》(GB8978-1996)中的一级排放标准。     

生物法处理含油污泥的研究进展

随着石油产业的不断发展,导致含油污泥产量越来越大。含油污泥成分复杂,乳化严重,难于处理,直接排放对环境危害极大。生物法处理含油污泥具有成本低、无二次污染等优点,因此受到国内外学者的广泛关注。主要介绍了几种含油污泥的生物处理方法,包括:生物堆肥法、联合生物法、生物反应器法、生物修复法和生物浮选法,并对生物法处理含油污泥未来的发展提出了一些建议,以期为相关研究提供参考。     

High strength wastewater treatment in a jet loop membrane bioreactor: kinetics and performance evaluation

Treatment of wastewater containing high organic matter was investigated by means of a jet loop bioreactor combined with a membrane process. Volume of jet loop bioreactor and area of membrane filtration unit were 23 l and 155 cm² respectively. It was found that jet loop reactor had high mass transfer coefficient (K_La) varying from 58.8 to 486 h^-1 depending on the water flow rate (i.e. power input) and air flow rate. Oxygen transfer efficiency and oxygenation capacity of the reactor varied from 12 to 22.5% and from 0.2 to 1.8 , respectively. The efficiency of jet loop membrane bioreactor was found to be approximately 97% for a volumetric organic load of 2- over a period of 10 weeks. The reactor was not disturbed from the organic loads up to , but the treatment efficiency decreased to about 60% at higher organic loads. This decrease was due to insufficient oxygen transfer rate. The relationship between the effluent substrate concentration and the specific oxygen uptake rate (SOUR) values was determined. Applied food/microorganism (F/M) ratio was varied between 2.5 and . Critical sludge age of the system () was evaluated to be 7.2 h. Sludge with unsatisfactory settling characteristics formed at high F/M values under turbulent conditions. Therefore, membrane process was used for solid-liquid separation and effluent solid concentration was approximately zero. Specific cake resistances (α) changed with F/M ratio. It was found that permeate fluxes were significantly effected with F/M ratio much more than mixed liquor suspended solids (MLSS). Average flux was for pore sized cellulose acetate membrane. It was concluded that the jet loop membrane bioreactor has distinctive advantages such as the ability to treat high strength wastewater, low area requirements and easy operation.     

生物法处理制药废水的研究进展

制药工业废水的种类较多,主要包括抗生素生产废水、合成药物废水、中成药生产废水以及各种制剂生产过程所产生的洗涤水和冲洗废水。特点是成分复杂、有机物含量高、毒性较大、色度深和含盐量较高,尤其是生化性很差,且间歇排放,属难处理的工业废水。介绍了SBR法、UASB法、水解酸化、膜生物等技术在制药废水处理方面的研究现状,幵对今后的研究方向提出了建议。     

Comparison of the filtration characteristics between biological powdered activated carbon sludge and activated sludge in submerged membrane bioreactors

The filtration performances of submerged membrane bioreactors (SMBR) with and without the addition of powdered activated carbon (PAC) were investigated respectively under the same feed and operation conditions. A series of experiments were conducted to analyze near-critical flux, effect of air-scouring rate and time of stable filtration operation of both systems. The experimental results demonstrated that pronounced flux enhancement was achieved by adding 1.2 g/L PAC. The near-critical flux for the biological powdered activated carbon (BPAC) system was about 32% higher than that for the activated sludge (AS) system. Increasing the air-scouring rate led to a more significant flux improvement for the BPAC system compared to the AS system. Long-term operation indicated that, at constant flux, the TMP increasing rate of the BPAC system could be lagged and thus cause the extension of operating intervals about 1.8 times compared to the AS system. Quantitative calculations showed the total hydraulic resistance of the BPAC system was about 44% lower than that of the AS system, and this decrease was mainly caused by the reduction in cake resistance. Analyses were then made from various aspects such as floc size distribution and apparent viscosity of the mixed liquor to elucidate the major factors giving rise to different filtration characteristics.     

Optimising mixing and nutrient removal in membrane bioreactors: CFD modelling and experimental validation

Membrane Bioreactors (MBRs) have been used successfully in biological wastewater treatment to solve the perennial problem of effective solids-liquid separation. The optimisation of MBRs requires knowledge of the membrane fouling, mixing and biokinetics. MBRs are designed mainly based on the biokinetic and membrane fouling considerations even though the hydrodynamics within an MBR system is of critical importance to the performance of the system. Current methods of design for a desired flow regime within the MBR are largely based on empirical techniques (e.g. specific mixing energy). However, it is difficult to predict how vessel design in large scale installations (e.g. size and position of inlets, baffles or membrane orientation) affects hydrodynamics, hence overall performance. Computational Fluid Dynamics (CFD) provides a method for prediction of how vessel features and mixing energy usage affect the hydrodynamics and pollutant removal and subsequently allowing optimisation of MBR design and performance. In this study, a CFD model was developed which accounts for aeration and biological nutrient removal. The modelling results are compared against experimental results of two full scale MBRs for the hydrodynamics and against a modelling benchmark for the biological nutrient removal component of the model.     

The use of RO to remove emerging micropollutants following CAS/UF or MBR treatment of municipal wastewater

The removal of various organic micropollutants (OMPs), including six antibiotics (ERY, ROX, CLA, SMX, SMZ, and TMP), three pharmaceuticals (ibuprofen, salicylic acid, and diclofenac), one industrial product (BPA), and one hormone (cholesterol), was investigated in two pilot plants treating the same raw sewage of the Tel-Aviv WWTP. The effluent production by CAS-UF was 45 m³/h while that of MBR was 40 L/h. Each system's effluent constituted the feed for its RO, which comprised three RO steps after the CAS/UF and a semi-batch RO system after the MBR. Despite significant molecular differences between the selected OMPs, high removal rates were achieved after the RO stage (> 99% for macrolides, pharmaceuticals, cholesterol, and BPA, 95% for diclofenac, and > 93% removal of sulfonamides). However, low antibiotics concentrations and 28–223 ng/L residuals of ibuprofen, diclofenac, salicylic acid, cholesterol, and BPA in the MBR/RO and CAS-UF/RO permeates showed that although RO is an efficient removal solution, it cannot serve as an absolute barrier to OMPs. Therefore, additional treatment techniques should be considered to be incorporated aside the RO to ensure complete removal of such substances.     

膜生物反应器处理小区污水条件的优化

由于膜污染是限制膜生物反应器(MBR)应用与推广的主要因素。为此,本研究以MBR处理某小区污水为例,选择粉末活性炭投加量、活性污泥浓度及曝气量进行L12(43)正交试验,确定最佳的操作条件分别为2 g/L、7 g/L、6 m3/h;并在此基础上进行平行对比试验,其膜阻的最大差值达21.05 kPa,导致膜污染形成和发展的主要物质蛋白质/多糖值与膜压差上升速率存在线性关系。     

EM技术在MBR中的应用研究

实验采用投加EM菌强化的MBR工艺处理某印染厂排放废水,考察了强化MBR的处理效果和对活性污泥特性的影响,以及对膜过滤性能的影响。EM菌按0.5%的比例投入MBR,并启动反应器,在水温25℃,pH=7,水力停留时间12 h,溶解氧浓度3~5 mg/L的条件下运行60 d。实验表明,EM菌强化的MBR工艺对TOC的平均去除率高于未强化组20%,具有更好的出水水质。此外,EM菌的强化作用使活性污泥具有更好的生物活性和更大的粒径,同时在一定程度上缓解了膜污染。     

MBR工艺在制药工业废水处理中的设计及应用

通过对MBR在制药工业废水处理中的设计技术要求及应用效果分析,总结MBR的技术和经验,为MBR在制药废水处理领域中的设计及应用提供参考。     

MBR技术在啤酒废水处理中的应用

结合啤酒废水水质特点和MBR技术的优点,阐述了MBR处理啤酒废水的优势,综述了好氧MBR、厌氧MBR以及厌氧-好氧MBR处理啤酒废水的试验研究现状,介绍了MBR组合工艺在工程中的应用效果和膜污染防治方法,在此基础上展望了MBR技术在啤酒废水中的应用前景。     

MBR在水处理中的应用与研究

阐述膜生物反应器的分类、原理，总结了MBR在水处理领域中的应用现状，讨论了膜生物反应器对污染物的去除机理，并就膜的污染及其解决办法进行评述。