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.     

Membrane bioreactors for hospital wastewater treatment: recent advancements in membranes and processes

Discharged hospital wastewater contains various pathogenic microorganisms, antibiotic groups, toxic organic compounds, radioactive elements, and ionic pollutants. These contaminants harm the environment and human health causing the spread of disease. Thus, effective treatment of hospital wastewater is an urgent task for sustainable development. Membranes, with controllable porous and nonporous structures, have been rapidly developed for molecular separations. In particular, membrane bioreactor (MBR) technology demonstrated high removal efficiency toward organic compounds and low waste sludge production. To further enhance the separation efficiency and achieve material recovery from hospital waste streams, novel concepts of MBRs and their applications are rapidly evolved through hybridizing novel membranes (non hydrophilic ultrafiltration/microfiltration) into the MBR units (hybrid MBRs) or the MBR as a pretreatment step and integrating other membrane processes as subsequent secondary purification step (integrated MBR-membrane systems). However, there is a lack of reviews on the latest advancement in MBR technologies for hospital wastewater treatment, and analysis on its major challenges and future trends. This review started with an overview of main pollutants in common hospital wastewater, followed by an understanding on the key performance indicators/criteria in MBR membranes (i.e., solute selectivity) and processes (e.g., fouling). Then, an in-depth analysis was provided into the recent development of hybrid MBR and integrated MBR-membrane system concepts, and applications correlated with wastewater sources, with a particular focus on hospital wastewaters. It is anticipated that this review will shed light on the knowledge gaps in the field, highlighting the potential contribution of hybrid MBRs and integrated MBR-membrane systems toward global epidemic prevention.     

Membrane bioreactor technology for wastewater treatment and reuse

Treatment technology for water recycling encompasses a vast number of options. Membrane processes are regarded as key elements of advanced wastewater reclamation and reuse schemes and are included in a number of prominent schemes world-wide, e.g. for artificial groundwater recharge, indirect potable reuse as well as for industrial process water production. Membrane bioreactors (MBRs) are a promising process combination of activated sludge treatment and membrane filtration for biomass retention. This paper will provide an overview of the status of membrane bioreactor applications in municipal wastewater reclamation and reuse in Europe and will depict their potential role in promoting more sustainable water use patterns. Particular attention will be paid to the impact of MBR technology on emerging pollutants. A case study will be presented on a full-scale MBR plant for municipal wastewater which is operated by Aquafin in Belgium.     

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.     

管式膜MBR在印染废水处理工艺中的运行规律研究

以模拟印染废水为研究对象,探讨管式膜MBR在印染废水处理过程中的运行情况.试验结果表明,当MLSS质量浓度为8g·L~(-1)左右,HRT为8h时,管式膜MBR对COD的去除率为82%,对色度的去除率为80%.有机物的去除主要取决于生物反应的效果,膜的截留作用进一步强化了MBR对色度和COD的去除效果.污泥浓度对膜通量的整体衰减程度影响很小,但对初始膜通量的影响较大.     

Influence of sludge loadings and types of substrates on nutrients removal in MBRs

It has been shown that by combining the patented process for biological phosphorus removal with post-denitrification without additional carbon dosing in membrane bioreactors (MBRs) good nutrient eliminations can be achieved. Especially, reported denitrification rates are higher than expected ones. The reason for this is not understood yet but a correlation between acetate dosing in batch trials and DNR has been reported. The present study investigated the influence of COD sludge loading and acetate inflow concentration on denitrification rates in continuous MBRs. A laboratory scale MBR operated with synthetic wastewater was switched from a multi to a mono substrate (acetate) wastewater and compared to three other MBR connected to separate sewer systems. Better eliminations for COD, TN and TP for the MBR operated with acetate were expected. However, elimination efficiencies were on a good level for all plants and configurations (eliminations: 94-97% COD, 86-94% TN, 92-99% TP) and no significant increase for mono substrate could be found. Average denitrification rate and TN elimination was even a bit lower with mono substrate. For increasing COD sludge loads increasing denitrification rates could be found. However, the variation within the rates has proved that many different influences have to be considered.     

Performance and kinetics of membrane and hybrid moving bed biofilm‐membrane bioreactors treating salinity wastewater

A pilot‐plant membrane bioreactor (MBR) and two pilot‐plant hybrid moving bed biofilm reactor–membrane bioreactors (MBBR–MBRs), divided into three aerobic and one anoxic chambers, were started up for the treatment of salinity‐amended urban wastewater. The MBBR–MBR systems worked with and without carriers in the anoxic zone (MBBR–MBRanox and MBBR–MBRn/anox, respectively). The systems were operated from start‐up to stabilization, showing high removal of organic matter—a maximum of 90% chemical oxygen demand and 98% biochemical oxygen demand on the fifth day for MBBR–MBRn/anox in the stabilization phase—but low nitrogen elimination—30% maximum for MBBR–MBRn/anox in the stabilization phase. Biofilm attached to carriers reached less than 50 mg L^?1 in the hybrid system. MBR showed faster kinetics than the two MBBR–MBR systems during start‐up, but the opposite occurred during stabilization. Maximum specific growth rates for heterotrophic and autotrophic biomass were 0.0500 and 0.0059 h^?1 for MBBR–MBRn/anox in the stabilization phase. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3329–3342, 2017     

The effect of biomass adsorption on the removal of selected pharmaceutical compounds in an immersed membrane bioreactor system

BACKGROUND: The performance of a pilot membrane bioreactor system (MBR) was tested for the treatment of municipal wastewater, with emphasis on the capability for removal of selected pharmaceuticals RESULTS: The MBR showed excellent performance with regards to conventional pollutants. However, the removal of specific pharmaceuticals was not as high. Carbamazepine and 17 α‐ethinyl estradiol showed the lowest removal, with mean removal rates of around 20%. Clofibric acid showed the highest removal 70%, while for 17β‐estradiol the mean removal was 40%. In order to distinguish between the two basic mechanisms of removal, adsorption on biomass and biodegradation, adsorption studies on inactivated biomass were performed and mass balances were written for the four pharmaceuticals. The immediate removal observed for the three compounds during short hydraulic retention times may have been primarily due to adsorption. CONCLUSIONS: The removal of carbamazepine, 17β‐estradiol and 17α‐ethynil estradiol, as well as half of the removal of chlofibric acid could be attributed to direct adsorption on biomass within the hydraulic residence time of the reactor. Copyright © 2011 Society of Chemical Industry     

Bioreaktionstechnik in mikrofluidischen Reaktoren

In the last decade micro bioreactor (MBR) technology has made rapid advances in biotechnology process development and in the investigation of various biological systems from industrial to pharmaceutical biotechnology applications. MBRs range in complexity from simple micro titer‐based systems to complex automated parallel bioreactors designed to allow the meaningful scale‐up/ ‐down of conventional pilot and large‐scale bioprocesses. MBR technology and the capability to monitor cultivation process variables in situ, provide real‐time and quantitative data from the microliter cultivation. This paper gives an overview of micro technologically fabricated MBRs, for the high‐throughput operation, its design, advantages and current limitations and potential future challenges in different biotechnological fields.     

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.     

膜生物反应器在污水处理中的研究进展

膜生物反应器是近年来发展起来的传统生物处理单元与膜分离技术有机结合的高效污水处理新技术,具有常规污水处理工艺无法比拟的优势。本文介绍了膜生物反应器的主要类型及在国内外污水处理中的研究进展,分析了膜生物反应器应用过程中存在的主要问题及解决措施,展望了其应用前景,为今后MBR的进一步研究发展奠定基础。     

膜生物反应器中污泥特性对膜污染的影响研究

膜生物反应器(MBR)是膜技术与污水生物技术的组合工艺，与传统污水处理工艺相比具有许多优点，但膜污染目前仍是限制MBR广泛应用的突出问题。有效的膜污染防治技术，可以增加膜通量，增强系统稳定性，减少系统维护和运行费用。在膜过滤过程中，污泥混合液的特性对于膜污染具有重要作用。近年来围绕污泥特性对膜污染的防治问题取得了许多研究成果，膜污染的数学模型研究也得到了很大发展。     

AHL-QS减缓膜生物反应器膜污染研究进展

首先介绍N-乙酰高丝氨酸环内酯（N-acyl homoserine lactone,AHL）型生物群体感应（quorum sensing,QS）信号分子对膜生物反应器（membrane bioreactor,MBR）膜表面形成生物膜的调节机制,通过AHL-QS信号分子细胞间的交流,可决定生物膜形成及胞外聚合物（extracellular polymeric substances,EPS）分泌;系统阐述了应用AHL-QS信号分子降解酶及淬灭剂对MBR生物膜污染的控制效果,抑制或降解信号分子可显著降低生物膜形成能力,从根本上控制膜污染。此外,针对降解酶及淬灭剂新的固定化技术在MBR中的应用也作了介绍,如磁性载体、膜表面负载、微生物-管束及多孔微球包埋细胞技术。以AHL-QS为基础的膜污染控制策略对于MBR应用前景广阔,然而该技术的工程化研究仍有待进一步深入;加强AHL-QS信号分子识别及进一步明确QS系统对微生物代谢机制的影响是该领域未来重要的研究方向。     

SRT对膜生物反应器（MBR）的污泥活性和硝化性能的影响

考察了SRT分别为10 d和不排泥2种情况下MBR的运行效果和污泥特征的变化,研究结果表明,随着SRT的减小,比耗氧速率从不排泥时的10.2 mg O2/g SSh增加至SRT为10 d时的15.9 mg O2/g SSh,排泥有助于提高污泥的活性。不排泥运行和SRT为15 d两种情况的处理效果基本相同,去除效率均超过90%,继续提高氨氮负荷,M2出水NH4-N浓度增加,因此污泥停留时间应该根据不同的水质来设定。     

膜生物反应器处理废水技术研究的进展

引用了40篇参考文献，综述了膜生物反应器处理生活污水及有机废水的特点，重点阐述了膜生物反应器中超滤膜污染的主要原因及相应的防治措施，并就膜生物反应器的研究现状，提出一些建议。     

Mathematical modeling of aerobic membrane bioreactor (MBR) using activated sludge model no. 1 (ASM1)

Activated sludge model no. 1 (ASM1) was applied to an aerobic membrane bioreactor (MBR) treating dilute municipal wastewater. The model for the aerobic MBR was calibrated using the data collected from a lab-scale aerobic MBR using AQUASIM 2.0. The performance of MBR process in terms of chemical oxygen demand (COD) removal and ammonia nitrogen (SNH) nitrification was studied at different operating conditions such as hydraulic retention time (HRT), solid retention time (SRT) and mixed liquor suspended solids (MLSS) concentrations. The characteristics of influent wastewater, pre-settled primary effluent from a wastewater treatment plant (City of Elmhurst WWTP, Elmhurst, IL, USA), were determined in the laboratory and used for the calibration of the model. The results from the simulations provided a better understanding of the mechanisms and kinetics of the MBR process including sludge removal.     

A Review of Membrane Fouling in MBRs: Characteristics and Role of Sludge Cake Formed on Membrane Surfaces

Abstract

Membrane bioreactor (MBR) has been deemed to be a promising technology for wastewater treatment and reclamation; however, the MBR filtration performance inevitably decreases with filtration time attributed to the deposition of soluble and particulate materials onto and into the membrane under the interactions between activated sludge components and the membrane. Cake layer formation on membrane surfaces has been a major challenge in the operation of MBRs under supra-critical flux operation, and/or caused by uneven distribution of aeration intensities, etc.; however, it was argued that a thin cake layer might improve filtration operation by some researchers. This paper provides a critical review on the formation mechanisms, properties, the role of sludge cake in membrane filtration, and the corresponding strategies of controlling cake fouling in MBRs. Drawbacks and benefits of the formation of sludge cake were also discussed in order to better understand the characteristics and role of sludge cake formation in MBRs.     

Research and applications of membrane bioreactors in China: Progress and prospect

In the past 15 years, remarkable progress has been achieved on the research and commercial applications of membrane bioreactor (MBR) technology in China. The objective of this paper is then to critically review the research achievements and to specifically present commercial applications of MBR in China. A total of 722 scientific papers published in peer-reviewed journals (600 Chinese papers and 122 English papers) written by Chinese authors from 1991 to 2006 and 254 full-scale MBR plants constructed in China were used as the analysis database. The number of articles published in journals together with organizations involved in MBR research saw a significant increase from 2001 to 2006, and much research progress was made during this period. From geographic distribution of these studies, it was found that the majority of the studies were carried out in North China, East China and North-East China. The research mainly focused on biomass separation MBR (BSMBR) with limited studies on extractive MBR (EMBR) and membrane aeration bioreactor (MABR), etc., and research contents included MBR configuration and type, membrane material and module, membrane fouling and control, characteristics of various wastewater treatment and other aspects like gas removal and microbial fermentation, etc. For commercial applications in China, a total of 254 MBR plants for municipal and industrial wastewater treatment were constructed by a lot of home-grown companies such as Tianjin Motimo Membrane Technology Co., Ltd. and Beijing Origin Water Technology Co., Ltd. and overseas-funded companies like Toray (Japan), Zenon (Canada), Mitsubishi-Rayon (Japan), etc. MBR plants with large treatment capacity will be built in future especially in North China due to the great need of water reclamation and reuse. Potential areas of MBR application include surface/drinking water treatment, gas diffusion and removal, membrane assisted fermentation for biological substance transformation and production, etc.     

MBR工艺处理腈纶废水研究进展

通过对干法腈纶废水的产生及其特点以及它的处理研究现状的描述,对国内腈纶生产废水处理方法和现状进行了分析,认为目前国内已工业化应用的腈纶废水处理技术不能达到理想效果。膜生物反应器(membrane,简称MBR)是通过膜技术来强化生物反应器的废水处理新工艺。针对水资源短缺、水污染严重和用水量增加的状况,应用膜生物反应器(MBR)处理腈纶污水,以推动我国含氰废水处理技术的不断完善和发展。     

The Impact of Intermittent Aeration on the Operation of Air‐Lift Tubular Membrane Bioreactors under Sub‐Critical Conditions

Abstract

An air‐lift sidestream polymeric multi‐tube membrane module has been investigated to compare the hydraulic performance of an MBR challenged with municipal wastewater and landfill leachate. In both cases the MBRs were operated under the same conditions of membrane aeration rate and sludge retention time, but with hydraulic retention time for the leachate set by scoping trials based on porous pots to 48 hours. Operation under conventional continuous aeration conditions yielded critical flux values, based on classical flux step experiments, of 36–42 l m^?2 hr^?1 for the sewage‐fed trial compared with ～24 l m^?2 hr^?1 for the leachate‐fed trial. Substantial improvements in operating flux, between 20 and 100%, were obtained when operating with air pulsing (1s on/s off). Intermittent operation under more conventional conditions (5s on/5s off) yielded no improvement.