Moving Bed Membrane Bioreactor Research Articles

Integrated attached and suspended biomass moving bed membrane bioreactor for municipal wastewater treatment: performance and biokinetic study

Integrated attached and suspended biomass moving bed membrane bioreactor for municipal wastewater treatment: performance and biokinetic study

Removal of nutrients and pharmaceutical and personal care products in an electroconductive bed-membrane bioreactor (EcB-MBR): The role of conductive media

In our previous work, an electroconductive moving bed membrane bioreactor was developed by introducing conductive media into an electrically assisted membrane bioreactor (EMBR). It incorporated microbial degradation, electrochemical processes, and membrane filtration for enhanced simultaneous removal of organics and nutrients. However, the additional aeration energy for suspending conductive media in the mixed liquor and the consumption of the reactive anode left bottlenecks for its broader application. In this study, an electroconductive bed membrane bioreactor (EcB-MBR) was developed. Graphite felt at a packing density of 0.10 (v/v) was equipped as the conductive media, and the anode was composed of a graphite electrode combined with iron. Simultaneous COD, TP, and TN removals of 98.5 ± 1.0%, 98.9 ± 0.7%, and 48.5 ± 14.9%, respectively, were achieved in the EcB-MBR. Specifically, TN removal significantly increased by approximately 89.5% compared with that in an EMBR under the same operating conditions (5 min-ON/5 min-OFF at 6.67 A/m2). The conductive media reduced the resistivity of mixed liquor, which enhanced electrochemical processes. In addition, the felt configuration served as a biocarrier and provided more reaction sites for microbiological activity. A 45.5% reduction in extracellular polymeric substances was observed in the EcB-MBR, probably due to the local electrochemical oxidation occurring on the conductive media. Nevertheless, insignificant membrane fouling control was achieved due to the fixed operating mode of the conductive media. Furthermore, the EcB-MBR successfully eliminated up to approximately 98% of several selected pharmaceutical and personal care products, demonstrating its ability to handle emerging contaminants in municipal wastewater.

Moving bed membrane bioreactor treating wastewater low load paper production industry: analysis ofperformance and clogging of membranes

RESUMO O processo de biorreator com membranas tem se consolidado nos últimos anos como uma alternativa aos métodos tradicionais para o tratamento de efluentes da indústria de produção de papel. Recentemente, a introdução de material suporte nesses reatores tem contribuído para a melhoria de seu desempenho, tendo em vista a maior atividade biológica que se verifica em decorrência do desenvolvimento de biofilme. Assim, a presença da biomassa aderida confere uma capacidade adicional ao biorreator com membranas em suportar choques de cargas, bem como pode contribuir para a biodegradação de compostos potencialmente tóxicos e recalcitrantes como derivados da lignina. Desse modo, o presente trabalho teve como objetivo avaliar o desempenho de um biorreator à membrana de leito móvel operado em batelada sequencial e aplicado ao tratamento de efluente real de baixa carga oriundo da produção de papel. O reator foi avaliado quanto ao seu desempenho na remoção de demanda química de oxigênio solúvel, fenol total, cor verdadeira, compostos aromáticos (UV254nm) e lignínicos (UV280nm). Paralelamente, o reator foi avaliado quanto ao processo de colmatação das membranas, por meio do monitoramento da pressão transmembrana, da concentração de substâncias poliméricas extracelulares e produtos microbianos solúveis). Nas condições testadas, o biorreator à membrana de leito móvel operado em batelada sequencial atingiu eficiência média de remoção de 89% para demanda química de oxigênio solúvel, 39% para UV254nm, 38% para UV280nm, 57% para cor verdadeira e 73% para fenóis totais. Em relação à colmatação das membranas, as variáveis UV254nm, UV280nm e fenóis totais correlacionaram-se diretamente com o aumento da pressão transmembrana (PTM).

Purification of polluted surface water by sponge moving bed membrane bioreactor with short hydraulic retention time operation

AbstractA sponge moving bed membrane bioreactor (SMB‐MBR) was developed for high‐rate biological purification of polluted surface water for nonpotable utilization purposes. The SMB‐MBR contains polyurethane sponge cubes (10% v/v) and submerged hollow fibre membranes in a solid separation compartment and operated under a short hydraulic retention time of 1 h. High organic (96% biochemical oxygen demand [BOD], 85% soluble chemical oxygen demand [COD] and 84% COD) and nitrogen (99% ammonium nitrogen [NH4+], 98% total Kjeldahl nitrogen [TKN] and 87% total nitrogen [TN]) removals were achieved. In the SMB‐MBR, the suspended and attached biomass were allowed to develop under no sludge wastage operation. The co‐existence of heterotrophs, nitrifiers and denitrifiers in the biomass was confirmed under a high oxygen environment. Sustainable operation of SMB‐MBR could be achieved by maintaining stable membrane flux without chemical cleaning for 60 days. This research demonstrates the technical feasibility of applying the SMB‐MBR for clean water production when the polluted surface is the only raw water source.

Effects of coarse and fine bubble aeration on performances of membrane filtration and denitrification in moving bed membrane bioreactors

In this study, two lab-scale Moving Bed Membrane Bioreactors (MBMBR) were setup and operated in parallel to study the effect of coarse and fine bubble aeration on the performances of membrane filtration and denitrification treating domestic wastewater. The bacterial populations in the two MBMBRs were further analyzed to investigate the mechanisms involved in the different denitrification performances. The results showed that coarse bubble aeration could effectively mitigate membrane fouling by decreasing the formation of cake layer, although smaller sizes of bio-flocs were induced. In addition, coarse bubble aeration could also maintain dissolved oxygen (DO) at a relatively lower level without compromising the moving of bio-carriers, which achieved 10% higher total nitrogen removal rate due to anoxic zone created at inner layers of biofilms on bio-carriers. Accumulation of denitrifier (Thiobacillus denitrificans) on the bio-carriers was found under the coarse bubble aeration system, which can explain its superior denitrification performance.

Highlighting the cathodic contribution of an electrooxidation post-treatment study on decolorization of textile wastewater effluent pre-treated with a lab-scale moving bed-membrane bioreactor.

This study is carried out to investigate the effect of the cathodic contribution in the performance of electro-oxidation process for decolorization of the textile wastewater effluent pre-treated with a lab-scale moving bed-membrane bioreactor. For this purpose, titanium dioxide (TiO2) was used as anode electrode and four different cathodic electrode materials: Graphite, TiO2, TiO2-coated Platine, and TiO2-coated ruthenium dioxide (RuO2) (namely RuO2) were tested and compared for their color removal efficiencies. Besides, the optimization parameters that affect color removal in correspondence to the electrode materials, such as applied current, electrolysis time, and pH were studied. In this context, the optimum parameters for each electrode material were selected, and the color removal percentages were found as 92.95%, 91.58%, 91.40%, and 89.17% for TiO2/Graphite, TiO2/Platine, TiO2/TiO2, and TiO2/RuO2, respectively. Finally, the operational cost for each of the tested cathodic electrode materials was calculated in each of the studied optimization parameters making it easier and practical for the selection and evaluation of the electrode materials by the readers. The correlation coefficients (R2) were 81.2%, 87.1%, 86.7%, and 88.6% respectively as a result of the optimization study using the nonlinear regression modeling.

Electroconductive moving bed membrane bioreactor (EcMB-MBR) for single-step decentralized wastewater treatment: Performance, mechanisms, and cost

Membrane bioreactor (MBR) is an advantageous technology for wastewater treatment. However, efficient nutrient removal and membrane fouling mitigation remain major challenges in its applications. In this study, an electroconductive moving bed membrane bioreactor (EcMB-MBR) was proposed for simultaneous removal of organics and nutrients from domestic wastewater. The EcMB-MBR was composed of a submerged MBR, filled with electrodes and free-floating conductive media. Conductive media were introduced to reduce energy consumption in an electrochemical MBR, to improve nitrogen removal, and to mitigate membrane fouling. The results showed that COD, total nitrogen, and total phosphorus removal was up to 97.1 ± 1.4%, 88.8 ± 4.2%, and 99.0 ± 0.9%, respectively, in comparison with those of 93.4 ± 1.5%, 65.2 ± 5.3%, and 20.4 ± 11.3% in a conventional submerged MBR. Meanwhile, a total membrane resistance reduction of 26.7% was obtained in the EcMB-MBR. The optimized operating condition was determined at an intermittent electricity exposure time of 10 min-ON/10 min-OFF, and a direct current density of 15 A/m2. The interactions between electric current and conductive media were explored to understand the working mechanism in this proposed system. The conductive media reduced 21% of the electrical resistivity in the mixed liquor at a selected packing density of 0.20 (v/v). The combination of electrochemical process and conductive media specially enhanced the reduction of nitrate-nitrogen (NO3−-N) through hybrid bio-electrochemical denitrification processes. These mechanisms involved with electrochemically assisted autotrophic denitrification by autotrophic denitrifying bacteria. As a result, 5.2% of NO3−-N remained in the effluent of EcMB-MBR in comparison with that of 29.5% in the MBR. Membrane fouling was minimized via both mechanical scouring and electrochemical decomposition/precipitation of organic/particulate foulants. Furthermore, a preliminary cost analysis indicated that an additional operating cost of 0.081 USD/m3, accounting for 10 – 30% increment of the operating cost of a conventional MBR, was needed to enhance the nitrogen and phosphorus removal correspondingly in the EcMB-MBR.

Performance evaluation of conventional membrane bioreactor and moving bed membrane bioreactor for synthetic textile wastewater treatment

In this study, conventional membrane bioreactor (MBR) and moving bed-membrane bioreactor (MB-MBR) processes were compared in synthetic textile wastewater treatment. For this purpose, the bioreactors were operated as a conventional MBR, an MB-MBR with a biocarrier filling ratio of 20 % and an MB-MBR with a biocarrier filling ratio of 10 %, respectively. In the conventional MBR operation, 93.1 % chemical oxygen demand (COD) and 87.1 % color (Reactive Red 390) removal efficiencies were obtained. In both MB-MBR operations, almost equal COD and color removal efficiencies were found as 98.5 % and 89.5 %, respectively. Moreover, offline physical and chemical membrane cleaning processes were applied every other day and every 15 days throughout the conventional MBR operation, respectively, while no physical or chemical membrane cleaning was required during both MB-MBR operations. Furthermore, lower polysaccharide concentrations of extracellular polymeric substances (EPS) and floc sizes of sludge and higher zeta potential of sludge were determined in MB-MBR. Considering the obtained results, it may be stated that the MB-MBR process is an attractive treatment technology for reducing membrane fouling propensity for treatment of textile wastewater.

Antifouling behaviour of a photocatalytic modified membrane in a moving bed bioreactor for wastewater treatment

Membrane fouling is a major bottleneck in the application of moving bed-membrane bioreactors. A novel moving bed-UV-photocatalytic-modified membrane bioreactor (MB-UVPMBR) was proposed for efficient wastewater treatment and membrane fouling mitigation. Herein, the modified membrane served as photocatalysis and membrane processes simultaneously. Compared with the conventional moving bed-membrane bioreactor (MBMBR) and MB-UVPMBR without UV light irradiation, the MB-UVPMBR exhibited good effluent quality and anti-fouling ability with UV light irradiation. The cake layer resistance was reduced by 83%, and the pore blockage resistance was reduced by 88%, thus reducing the total membrane filtration resistance. The hydrophilicity of the modified membrane helped mitigate foulant deposition and cake layer formation on the membrane surface. The modified membrane effectively reduced the contents of soluble microbial products and foulants deposited on the membrane surface by photocatalysis. Additionally, the fouled membrane could be effectively regenerated by self-cleaning.

Development of a moving-bed electrochemical membrane bioreactor to enhance removal of low-concentration antibiotic from wastewater

Removal of low-concentration (ng/L ~ μg/L) antibiotics from water calls for the development of cost-effective treatment technologies. In this study, a novel moving-bed electrochemical membrane bioreactor (MEMBR) was developed for removing sulfamethoxazole (SMX). Results showed that the introduction of external electric field and carbon felt particles could efficiently eliminate SMX (removal efficiency of 88.9%). In contrast, the moving-bed membrane bioreactor (MMBR) took a long time to acclimate microorganism, reaching a removal efficiency of 43.9%. Transmembrane pressure increase rate was much lower in MEMBR (1.06 kPa/d) compared to MMBR (1.72 kPa/d). The presence of carriers increased the generation of reactive oxygen species, contributing to SMX removal. Microbial community analysis revealed that the introduction of electric field could increase microbial community richness/diversity and enrich the phyla of Actinobacteria and Gemmatimonadete, potentially capable of mineralizing SMX. These results clearly demonstrated the potential of this novel MEMBR to be used for enhanced micropollutants removal from water/wastewater.

Fouling Mitigation and Wastewater Treatment Enhancement through the Application of an Electro Moving Bed Membrane Bioreactor (eMB-MBR).

High operational cost due to membrane fouling propensity remains a major drawback for the widespread application of membrane bioreactor (MBR) technology. As a result, studies on membrane fouling mitigation through the application of integrated processes have been widely explored. In this work, the combined application of electrochemical processes and moving bed biofilm reactor (MBBR) technology within an MBR at laboratory scale was performed by applying an intermittent voltage of 3 V/cm to a reactor filled with 30% carriers. The treatment efficiency of the electro moving bed membrane bioreactor (eMB-MBR) technology in terms of ammonium nitrogen (NH4-N) and orthophosphate (PO4-P) removal significantly improved from 49.8% and 76.7% in the moving bed membrane bioreactor (MB-MBR) control system to 55% and 98.7% in the eMB-MBR, respectively. Additionally, concentrations of known fouling precursors and membrane fouling rate were noticeably lower in the eMB-MBR system as compared to the control system. Hence, this study successfully demonstrated an innovative and effective technology (i.e., eMB-MBR) to improve MBR performance in terms of both conventional contaminant removal and fouling mitigation.

The effect of the solids and hydraulic retention time on moving bed membrane bioreactor performance

The aim of the present paper was to investigate the effect of solids (SRT) and hydraulic (HRT) retention time on Integrated Fixed Film Activated Sludge (IFAS) University of Cape Town (UCT) membrane Bioreactor (MBR). In particular, three different pairs of SRT and HRT values were analysed, namely, Phase I 56 d/30 h, Phase II 31 d/15 h and Phase III 7 d/13 h. The short-term effect of these three SRT/HRT conditions was assessed by analysing several system performance indicators: organic carbon and biological nutrient (nitrogen and phosphorus) removal, biomass respiratory activity, activated sludge filtration properties and membrane fouling. The results showed that the decrease of SRT/HRT had a positive influence on system performance. Specifically, the IFAS-UCT-MBR showed excellent removal of organic matter - highest value (99%) at the shortest SRT/HRT (7 d/13 h). Also, the increase in organic loading rate resulting from the decrease of SRT and HRT led to improved nitrogen removal due to higher N removal by sludge wasting requiring less N removal (as N2) by denitrification. Complete nitrification of influent ammonia was achieved at all three SRT/HRT phases, guaranteed by the presence of biofilm carriers in the aerobic reactor, which ensured a higher media SRT than suspended biomass SRT. The increase of the organic loading rate and decrease in SRT led also to a higher heterotrophic activity as demonstrated by the respirometric batch tests, which is due to the increasing active biomass fraction of the volatile suspended solids as SRT decreases. The SRT/HRT decrease over the three phases resulted in an overall increase of the Extracellular Polymeric Substance concentration, which caused an increase in membrane fouling.

Performance of a novel hybrid membrane bioreactor for treating saline wastewater from mariculture: Assessment of pollutants removal and membrane filtration performance

A novel AF-MBMBR system (sponge moving bed membrane bioreactor coupled with a pre-positioned anoxic bio-filter) was proposed for treating saline wastewater from mariculture. Its development process was divided into 4stages and the performance in each stage were evaluated in order to clarify the pollutants removal mechanism and the membrane filtration performance. The results showed that TOC removal efficiency was maintained at high level (92.8%–96.2%) throughout the development period due to the utilization of pre-acclimated biomass; Excellent TN (total nitrogen) removal efficiency (up to 93.2%) was progressively obtained which could be attributed to the combined effects of pre-positioned AF and sponge bio-carriers in MBMBR. Indeed, such an effective TN removal for the treatment of saline wastewater was rarely reported. Moreover, the short-cut nitrification-denitrification was observed to be the dominant nitrogen removal pathway in AF-MBMBR. Concerning membrane filtration performance, the filtration cycle was pronouncedly prolonged from 10days to 44days. Such an improvement was the result of mitigation on cake layer resistance, which could be attributed to the reduction of MLSS and organic load in MBR induced by pre-positioned AF, as well as the modification effect of sponge bio-carriers on mixed liquor in MBR.

Membrane fouling mitigation in a moving bed membrane bioreactor combined with anoxic biofilter for treatment of saline wastewater from mariculture

Membrane fouling mitigation in a novel AF-MBMBR system (moving bed membrane bioreactor (10L) coupled with anoxic biofilter (4L)) under high salinity condition (35‰) was systematically investigated. Pre-positioned AF served as a pretreatment induced significant decrease of suspended biomass by 85% and dissolved organic matters by 51.7% in subsequent MBR, which resulted in a reduction of cake layer formation. Based on this, sponge bio-carriers in MBMBR further alleviated the fouling propensity by modifying extracellular polymeric substances (EPS) properties. The protein component in EPS decreased from 181.4 to 116.5mg/g MLSS, with a decline of protein/carbohydrate ratio from 4.6 to 3.4. In particular, elimination of hydrophobic groups like aromatic protein-like substance in EPS was detected. These caused the less biomass deposition on membrane surface, thereby alleviating membrane fouling. In summary, mitigation of membrane fouling in AF-MBMBR should be attributed to contributions from both pre-positioned AF and sponge bio-carriers.

Analysis of Extracellular Polymeric Substances and Membrane Fouling of a MB-MBR Treating Shipboard Slops

AbstractThis work concerns the simultaneous effects of salinity and hydrocarbons on the biological activity and membrane fouling of a moving bed-membrane bioreactor (MB-MBR) fed with real high-sali...

Moving bed membrane bioreactors for carbon and nutrient removal: The effect of C/N variation

In this paper, an experimental campaign was carried out on a University of Cape Town Integrated Fixed Film Activated Sludge Membrane Bioreactor (UCT-IFAS-MBR) pilot plant. The aim of the study was to evaluate the effect of the influent C/N ratio on the system performance in terms of organic carbon, nitrogen and phosphorus removal, biomass viability (through respirometry), activated sludge features and membrane filtration properties. The experiments were organized into three phases, characterized by a variation of the C/N ratio (namely, Phase I: C/N=5, Phase II: C/N=10; Phase III: C/N=2). The results highlighted that the system performance was significantly affected by C/N ratio. The removal efficiencies were satisfactory for C/N ratio equal to 10 and 5, with average removal in Phases I and II of 98–98%, 53–69% and 67–87% for COD, nitrogen and phosphorus, respectively. Conversely, with a C/N ratio of 2, a significant worsening of the pilot plant performance was observed, with average COD, nitrogen and phosphorus removal equal to 70%, 44% and 26%, respectively, much lower compared to the previous phases. Respirometry highlighted a significant decrease of bacterial activity when the C/N was reduced to 2, even if the biofilm seemed to be more resilient in terms of activity compared to the activated sludge.

Biological Nutrient Removal of Municipal Wastewater Using Two Hybrid Moving Bed Membrane Bioreactors and a Conventional Membrane Bioreactor

This study was the advent of a novel biofilm carrier that incorporated a high porosity fibrous packing inside a spherical high density polyethylene carrier. To test the validity of the media against another carrier, the industry standard finned cylindrical media was used as a control Moving bed membrane bioreactors (MBMBR) system. To investigate biofilm growth as a function of media size three spherical diameters were developed; 21 mm, 27 mm and 33 mm. Preliminary results for the range tested indicates that the 21 mm media has the highest capacity to accumulate biomass with 47% of the available volume colonized by biomass, whereas a standard finned cylindrical media only capitalized on 18% of available volume and the 27 mm spherical and 33 mm spherical both colonized 28% of available volume. In addition to media performance, the three bioreactors were assessed by analyzing mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), attached biomass, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (TOC), total nitrogen (TN), ammonia nitrogen, nitrate nitrogen and total phosphorous. Organic carbon removal was consistent in all three reactors with average BOD and COD removal exceeding 98% and 94% respectively.

Membrane fouling between a membrane bioreactor and a moving bed membrane bioreactor: Effects of solids retention time

In this study, a control membrane bioreactor (MBR) and a moving bed membrane bioreactor (MBMBR) were operated in parallel treating real domestic wastewater at the different solids retention time (SRT) of 20, 10 and 5d to investigate the membrane fouling behaviors and microbial community structures. Both the MBR and MBMBR were found less prone to membrane fouling under the longer SRTs. The MBMBR showed consistently superior membrane filtration performance, and the extension of membrane filtration time was more pronounced at the shortest SRT. From the characterization of the mixed liquor suspensions, it was found that the mitigation of membrane fouling in the MBMBR was probably attributed to the lower concentrations of biopolymers (including proteins and carbohydrates) and low molecular weight (LMW) compounds in the mixed liquor supernatant (MLS). The findings were further justified by the analysis of organic fractions in the fouling cake layer, where the biopolymers were found to play a significant role in the cake layer formation. Through DNA pyrosequencing analysis which can reveal microbial community structures, the abundance of Nitrospira spp. (one of key bacterial populations responsible for nitrification) was found to be largely affected by the SRT. More Nitrospira spp. could develop in the attached biofilm than in the suspended biomass under the shorter SRTs of 10 and 5d. Furthermore, predominance of an uncultured bacterial genus within family Saprospiraceae was found in the MBMBR at all the examined SRTs, which can be an important explanation for its lower concentrations of carbohydrates and proteins in MLS of the MBMBR.

Membrane fouling of a hybrid moving bed membrane bioreactor plant to treat real urban wastewater

The influence of operative variables in the performance of an ultrafiltration membrane in a hybrid moving bed membrane bioreactor treating real urban wastewater was studied in relation to the fouling rate and the recovery of permeability with a multivariable statistical analysis. Twenty-one cycles of operation were studied in relation to the filling ratio, flux, temperature, biomass concentration in a pilot-scale experimental plant. The pilot plant consisted of three units of ZW-10 submerged membrane and 20, 35 and 50% of K1 of Anoxkaldnes were used as carrier. The statistical analysis has shown that the most influential variables in the performance of the membrane were temperature and flux. Transmembrane pressure ranged from 22kPa to 68kPa, increasing with the MLSS, BFSS and flux and decreasing with temperature. The presence of biofilm negatively affected the performance of the membrane in relation to the fouling rate; this varied between 0.26 and 1.22kPa/day, and was found to increase when viscosity and BFSS increased and temperature decreased.

Performance of a moving bed-membrane bioreactor treating saline wastewater contaminated by hydrocarbons from washing of oil tankers

This work analyses the performance of a moving bed-membrane bioreactor (MB-MBR) in the treatment of saline wastewater contaminated by hydrocarbons from washing of oil tankers with seawater (slops). In order to allow a biomass acclimation, a gradual increase in salinity and total petroleum hydrocarbons (TPHs) were adopted during six experimental phases. The results showed that acclimation of heterotrophic strains to TPHs occurred during Phase IV (30% by volume of slop). This is confirmed by an evident increase in the biological removal efficiencies of chemical oxygen demand, total organic carbon and TPHs. In particular, the TPHs removal efficiency increased from about 8% up to the range of 35–70%. No inhibition of the ammonia oxidizing bacteria (AOB) was noted except for Phase VI (100% by volume of slop) characterized by a collapse of ammonium removal efficiency from about 95% to about 21–24%. An accumulation of nitrite at the end of Phase IV, suggested an inhibition of nitrite-oxidizing bacteria (NOB), while a simultaneous “salt-in” of bromide indicated the acclimation of the same strains to salinity. Moreover, the hydraulic performance showed a high increase in total resistance to filtration (RT) during the pseudo-stationary phases (from Phase I to Phase III) and during Phase VI, due to the high salinity and hydrocarbons concentration. The results showed that the MB-MBR system has high potentiality for the treatment of saline oily wastewater.