Submerged Membrane Bioreactor System Research Articles

Treatment Performance of Municipal Sewage in a Submerged Membrane Bioreactor (SMBR) and Mechanism of Biochar to Reduce Membrane Fouling

Submerged membrane bioreactors (SMBRs) are a promising technology for municipal sewage treatment, but membrane fouling has limited their development. In this study, biochar (BC), which has a certain adsorption capacity, was added to an SMBR to investigate its potential in treating municipal sewage and alleviating membrane fouling. The results showed that the average removal rates of ammonia nitrogen (NH4+-N), total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) were 94.38%, 59.01%, 44.15% and 83.70%, respectively. After BC was added and operation was stable, the ratio of mixed liquor volatile suspended solids to mixed liquor suspended solids (MLVSS/MLSS) was maintained between 0.78 and 0.81. The concentrations of soluble microbial products (SMPs) and extracellular polymeric substances (EPSs) were stabilized between 63.05 ± 8.49 mg/L and 67.12 ± 1.54 mg/L. Trans-membrane pressure (TMP) and scanning electron microscopy (SEM) analyses showed that BC reduced the TMP by reducing the thickness and compactness of the cake layer on the membrane surface. The high-throughput sequencing results showed that the microorganisms associated with biofilm formation (proteobacteria, γ-proteobacteria and α-proteobacteria) were significantly reduced in the BC-enhanced SMBR system. BC promoted the enrichment of functional microorganisms such as Chloroflexi, Acidobacteriota, Anaerolineae and Planctomycetes. Compared with traditional anti-fouling methods, the results of this study may provide a low-cost membrane fouling mitigation method for industrial applications of SMBRs.

Municipal wastewater treatment and recycle by an electrocoagulation process and a submerged membrane bioreactor system

To remove phosphates and nitrates from municipal wastewater, an electrocoagulation process with membrane bioreactor process (EC-MBR) was used. Experiments were carried out incrementally to evaluate the new design. In a lab-scale (EC-MBR) treatment of municipal wastewater, the structure and distribution of the organic matter removal utilizing the membrane are being examined. The study's objectives were to evaluate the efficiency of the Al-Hawraa wastewater's organic matter removal process for nitrate (NO-3) and phosphate (PO4-3) as well as how it related to machine learning indicators. It was chosen to use an EC-MBR with operational parameters of 25 Co, pH 7 and DO (4-6 mg/L), initial and final concentrations of NO-3 (4.4-0.6 mg/L), and (PO4-3) (6.0-0.1 mg/L) to collect and analyze effluent from municipal wastewater treated using biological and chemical methods. According to the results, it may be possible to measure the effectiveness of organic matter removal using a neural network method. The results also showed that an overall reactor had agreeablemaximum NO-3 and (PO4-3) removal efficiencies of (87.6% and 98.1%), respectively. The accuracy model by its (98.1 and 85.7) for both NO-3 and (PO4-3) was effective, according to the models' accuracy results.

Fabrication, characterization and treatment of polymeric membranes with submerged membrane bioreactor system: fruit juice industry wastewater

Fabrication, characterization and treatment of polymeric membranes with submerged membrane bioreactor system: fruit juice industry wastewater

Review: Reuse of Treated Wastewater

Abstract: Water reuse generally refers to the process of using treated wastewater (reclaimed water) for beneficial purposes such as agricultural and landscape irrigation, industrial processes, nonpotable urban applications (such as toilet flushing, street washing, and fire protection), groundwater recharge, recreation, and direct or undirected water supply. Its increased application has been facilitated by modern wastewater treatment processes that have advanced substantially during the twentieth century. Water Reuse is a reality at international. Several practices have emerged around the world as results of different needs, perspectives and policies. Accelerating development occurred in the past 15 years, especially in the application field of potable reuse. Technologies and treatment flowsheets have been studied and validated, demonstrating advanced water quality, safety and suitability for potable reuse applications. Reuse of wastewater after its treatment may be a good alternative for regions, which suffer from lack of pure water or have limited access to water resources. Effective water reuse applications require a combination of advanced treatment technologies. Increasingly these include a combination of low-pressure technologies MF/UF followed by NF/RO (high pressure) to provide a high-quality grade of water. Submerged membrane bioreactor systems (MBR) have also become a viable alternative for wastewater reuse technologies. Reuse technologies may be applied for municipal and industrial wastewater. Reuse of wastewater is only possible if sanitary and environmental safety is provided with no hazard for current ecosystem. That fact requires strict fulfilment of laws and regulation. Wastewater to be reused has to follow a certain sequence of treatment procedures to reduce concentration of pollutants in it. Water reuse (also commonly known as water recycling or water reclamation) reclaims water from a variety of sources then treats and reuses it for beneficial purposes such as agriculture and irrigation, potable water supplies, groundwater replenishment, industrial processes, and environmental restoration. Water reuse can provide alternatives to existing water supplies and be used to enhance water security, sustainability, and resilience that might be traditional methods (waste separation, sedimentation), methods of removal of certain components (nitrogen and phosphorus), disinfection

Direct visualization of hollow fiber membrane fouling distribution

Submerged membrane bioreactor system is commonly used for water and wastewater treatment processes. This system is a more economical alternative to conventional activated sludge process due to small footprint and better effluent quality. Nevertheless, membrane fouling is a major issue that requires further studies. This paper covers the use of an optical microscope to observe membrane fouling. Bentonite was used as model particles to simulate activated sludge. In-situ observation of particle deposition along the surface of hollow fiber membranes during filtration was performed at various operating conditions. Results from this studies indicated that the flux distribution was affected by the permeate flux and cross flow velocity. Lower CFV and higher flux caused the flux to be more non-uniformly distributed due to more severe fouling. These findings provided useful information to further improve the membrane module design to achieve more evenly distributed permeate flux.

Permeate Flux Control in SMBR System by Using Neural Network Internal Model Control

This paper presents a design of a data-driven-based neural network internal model control for a submerged membrane bioreactor (SMBR) with hollow fiber for microfiltration. The experiment design is performed for measurement of physical parameters from an actuator input (permeate pump voltage), which gives the information (outputs) of permeate flux and trans-membrane pressure (TMP). The palm oil mill effluent is used as an influent preparation to depict fouling phenomenon in the membrane filtration process. From the experiment, membrane fouling potential is observed from flux decline pattern, with a rapid increment of TMP (above 200 mbar). Membrane fouling is a complex process and the available models in literature are not designed for control system (filtration performance). Therefore, this work proposes an aeration fouling control strategy to measure the filtration performance. The artificial neural networks (Feed-Forward Neural Network—FFNN, Radial Basis Function Neural Network—RBFNN and Nonlinear Autoregressive Exogenous Neural Network—NARXNN) are used to model dynamic behaviour of flux and TMP. In this case, only flux is used in closed loop control application, whereby the TMP effect is used for monitoring. The simulation results show that reliable prediction of membrane fouling potential is obtained. It can be observed that almost all the artificial neural network (ANN) models have similar shape with the actual data set, with the highest accuracy of more than 90% for both RBFNN and NARXN. The RBFNN is preferable due to simple structure of the network. In the control system, the RBFNN IMC depicts the highest closed loop performance with only 3.75 s (settling time) for setpoint changes when compared with other controllers. In addition, it showed fast performance in disturbance rejection with less overshoot. In conclusion, among the different neural network tested configurations the one based on radial basis function provides the best performance with respect to prediction as well as control performance.

Foaming control and determination of biokinetic coefficients in membrane bioreactor system under various organic loading rate and sludge retention time

This work aims to control foaming in a submerged membrane bioreactor (SMBR) by optimizing the organic loading rate (OLR) and sludge retention time (SRT) values to decrease the extracellular polymeric substance (EPS) production used for the pharmaceutical wastewater treatment. Four lab-scale SMBRs were operated for a period of more than 8 months to determine the biokinetic coefficients and optimize the SMBR systems operation under the SRT of 5, 10, 15, 20, 25 days and OLRs of 0.03-0.32 gCOD/L.day. The investigation revealed that the lowest foaming quantity was at an organic loading rate of 0.32 gCOD/L.day and a sludge retention time of 15 days related to few protein concentration of EPS. The results also showed that the foaming quality at the OLR of 0.03 gCOD/L.day was higher compared to the greater OLRs in all SRTs. It was found that the yield (Y), the endogenous decay coefficient (kd), the maximum specific growth rate (μmax), and the saturation constant (Ks) of four SMBRs were in the range of 0.073-0.310 mg/mg, 0.985-3.119 day−1, 1.249-3.672 day−1, and 2.63-106.671–232.55 mg/mg, 1–3.156 day mgCOD/L, respectively. Furthermore, the most appropriate operating condition to activated sludge among the SMBRs was the OLR of 0.1 gCOD/L.day and SRT of 15 days. Under these optimum conditions, a 92.8 % COD removal efficiency and 3.708 1/day μmax were achieved.

Efficiencies of Organic Matters and Nitrogen Removal at Different Recycle Ratios in a SMBR System

The experiment in this study was conducted using wastewater treatment system constructed with anoxic reactor, selector, and aerobic reactor. The Submerged Membrane Bioreactor (SMBR) system was operated with a design flow of 50 m3/day, and the vertically double layer-submerged biological membrane was integrated with aerobic reactor. The objective of this study has been to help move towards an optimal design on the operation of submerged reactor treatment plants. In particular, this study has focused on the organic matters and nitrogen removal efficiency according to recycle ratios. The obtained results of experiment are as follows: BOD and COD, which are indicators of organic compounds were 96.50−98.50% and 92.90−97.00%, respectively. The measured ranges of BOD and COD indicated a reliable treatment efficiency, and similar efficiency was observed for suspended solids and coliform removal. These results could be applied to good effluent quality for suitable standards of the reuse water. The Recycle ratios in this study were 1, 1.5, 2, and 3; and the corresponding T-N removal efficiencies for each ratio were 54.10%, 69.80%, 76.60%, and 81.90%, respectively. It is observed that the removal efficiencies are increased in proportion to the recycle ratio. While the recycle ratio was increasing from 1 to 3, the removal efficiency increased 15.70%, 22.50% and 27.80%.

Treatment of cake shop wastewater by pilot-scale Submerged Membrane Bioreactor (SMBR)

In this work, the treatment of cake shop wastewater using Submerged Membrane Bioreactor (SMBR) on pilot-scale has been studied. The commercial hollow fiber membrane was used with a total surface area of 0.609 m2. The experiment was set up with three different conditions as follows: model 1 - the SMBR system used suspended activated sludge; model 2 – the SMBR system was combined with the substrate inside; model 3 – the SMBR system was added with PAC (Poly Aluminium Chloride) excluding substrate. Effects of organic loading rates (OLR) were investigated to assess the performance of each model. The results showed that the optimal OLR of model 1 achieved at 11 kgCOD/m3.day and COD, TN, TP removal efficiencies were 97.93%, 71.04% and 79.04%, respectively. The optimal OLR of model 2 was 13.3 kgCOD/m3.day and the COD, TN, TP removal efficiencies were 98.04%, 82.35% and 84.59%, respectively. 11 kgCOD/m3.day was optimal OLR for model 3 with COD, TN, TP removal efficiencies 98.10%, 73.35% and 84.70%, respectively. Trans-membrane pressure (TMP) of the whole operation was in range of 20 to 55.5 CmHg and flux values were observed in the range of 35.86 to 333.24 L/m2.h. Depending on discharge requirements, an approximate processing model for cake shop wastewater treatment is chosen.

Removal and degradation mechanisms of sulfonamide antibiotics in a new integrated aerobic submerged membrane bioreactor system

A novel laboratory-scale aerobic submerged membrane bioreactor integrating sponge-plastic biocarriers (SPSMBR) was conducted to study the removal and degradation mechanisms of sulfonamide antibiotics (SAs). Experimental results indicated that SPSMBR had a better removal of sulfadiazine (91% SDZ) and sulfamethoxazole (88% SMZ) than that of a conventional aerobic submerged membrane bioreactor (CSMBR) (76% SDZ and 71% SMZ, respectively). Material balance calculations suggested that biodegradation is the primary removal mechanism of SDZ and SMZ. Protein (tyrosine-like materials) significantly affected the removal of SAs. Moreover, the SPSMBR exhibited its better performance in removing SAs due to more abundance of tyrosine-like materials. The 16S rRNA sequencing showed that biocarriers could promote the enrichment of slow growing bacteria, especially Thermomonas, associated with the removal of SAs. Valuable insights into the removal and degradation mechanisms of SAs in the SPSMBR systems are documented here.

Long-term MBR performance of polymeric membrane modified with Bismuth-BAL chelate (BisBAL)

ABSTRACTAn ultrafiltration membrane prepared by polyethersulfone (PES) was modified with Bismuth-BAL chelate (BisBAL) and was used in submerged membrane bioreactor system. Moreover, a control membrane reactor was also tasked to evaluate the effect of BisBAL on the membrane performance. The flux profile, transmembrane pressure, the effect of chemical treatment, cake layer formation, anti-fouling properties against extracellular polymeric substances (EPS) and soluble microbial products (SMP) were studied. The UF modified membrane demonstrated a sustained permeability, low cleaning frequency, and longer filtration time. In terms of anti-EPS and SMP accumulation, the modified membrane showed a lower membrane resistance. It can be illustrated from scanning electron microscopy and confocal laser scanning microscope images that the modified membrane had presented better properties than bare PES membrane, as it was looser and thinner. Thus, the UF membrane proved to be more efficient in terms of permeability and lifetime.

Characterization of Active Biomass and Species by Means of Respirometric Technique from Activated Sludge Models

The aim of this work is to evaluate the performance of a submerged membrane bioreactor that operated continuously for 200 days and to assess biomass activity and membrane fouling under various operating conditions. Furthermore, a method for the characterisation of biomass activity is developed based on its separation into various fractions. Respirometry and Activated Sludge Models are used as biological process to identify active biomass and species of activated sludge. However, the equations describing the active biomass are developed. The submerged membrane bioreactor system operated at the solids retention times of 40 and 60 days with organic loading rate of 0.5635 kg/COD/m−3/day−1 and chemical oxygen demand/nitrogen ratio of 3.5. Activated sludge is generated in a system fed with soluble and easily biodegradable substrate [ethanol/sodium acetate (1:1)], this synthetic wastewater, containing no hardly biodegradable organic or inorganic particulate matter, has led to the generation of a sludge constituted essentially of two fractions: active biomass and cell debris.

Single house on-site grey water treatment using a submerged membrane bioreactor for toilet flushing

Wastewater recycling has been and continues to be practiced all over the world for a variety of reasons including: increasing water availability, combating water shortages and drought, and supporting environmental and public health protection. Nowadays, one of the most interesting issues for wastewater recycling is the on-site treatment and reuse of grey water. During this study the efficiency of a compact Submerged Membrane Bioreactor (SMBR) system to treat real grey water in a single house in Crete, Greece, was examined. In the study, grey water was collected from a bathtub, shower and washing machine containing significant amounts of organic matter and pathogens. Chemical oxygen demand (COD) removal in the system was approximately 87%. Total suspended solids (TSS) were reduced from 95mgL−1 in the influent to 8mgL−1 in the effluent. The efficiency of the system to reduce anionic surfactants was about 80%. Fecal and total coliforms decreased significantly using the SMBR system due to rejection, by the membrane, used in the study. Overall, the SMBR treatment produces average effluent values that would satisfy international guidelines for indoor reuse applications such as toilet flushing.

Membrane fouling control using high-frequency power vibration, in an SMBR pilot system—preliminary studies

AbstractMembrane bioreactors (MBRs) in wastewater treatment have gained significant popularity recently, especially due to reclamation needs. Submerged membrane bioreactors (SMBRs) are considered to be an extremely successful method for this purpose. However, membrane fouling is one of the most critical problems of the SMBR systems, and the used techniques to avoid this problem have the disadvantage of the high energy needed. The objective of this study was to introduce an alternative cleaning technique of submerged membranes, with reduced energy consumption. A lot of lab studies have been published concerning the impact of mechanical action in the removal of foulants from the membranes (e.g. vibration, buck-pulse, and ultrasound). In this preliminary study, the feasibility of high frequency power (or powerful) vibration (HFPV), as cleaning technique, on fouled membrane modules, in a small pilot-scale SMBR system, treating a novel synthetic wastewater was examined. This pilot-scale system comprised from s...

A submerged membrane bioreactor with pendulum type oscillation (PTO) for oily wastewater treatment: Membrane permeability and fouling control

In this study, a novel submerged membrane bioreactor (SMBR) with pendulum type oscillation (PTO) hollow fiber membrane modules was developed to treat oily wastewater and control the problem of membrane fouling. To assess the potential of PTO membrane modules, the effect of oscillation orientation and frequency on membrane permeability was investigated in detail. The forces exerted on sludge flocs in the oscillating SMBR were analyzed to evaluate the impact of membrane oscillating on the cake layer resistance reduction. Results showed that the optimized PTO SMBR system exhibited 11 times higher membrane permeability and better fouling controllability than the conventional MBR system. By hydrodynamic analysis, it was found that the cooperative effect of bubble-induced turbulence and membrane oscillation in PTO SMBR system generated strong shear stress at liquid-membrane interface in vertical and horizontal direction and effectively hindered the particles from depositing on membrane surface.

Effect of Mixed Liquor Volatile Suspended Solids on Membrane Fouling During Short and long-term Operation of Membrane Bioreactor

The aim of this study was to examine the impact of different Mixed Liquor Volatile Suspended Solids (MLVSS) concentrations on membrane fouling,in a submerged Membrane Bioreactor (MBR) at short and longterm MBRoperation for waste water treatment. Three laboratory-scale in a submerged MBR system were operated under critical flux, subcritical flux,and an intermittent suction time and backwashing conditions. At short-term MBR operation with mixed liquors of 4,200 and 6,150 mg MLVSSL−1, the hydraulic resistance of membranes followed a same trajectory with averages of 5.0E+12m−1, whereas for 7,940 mg MLVSSL−1, a highresistance of up to 1.7E+13m−1was obtained. The result showed thathigh biomass concentrations decreased to permeability due to a bio-layer formed in the membrane surface and high Extracellular Polymeric Substance (EPS).

On the performance of real grey water treatment using a submerged membrane bioreactor system

The performance of a submerged membrane bioreactor (SMBR) system for grey water (GW) treatment was evaluated in terms of effluent quality and membrane fouling. The SMBR was operated for 42 days at constant transmembrane pressure (13kPa) in six consecutive stages. A hollow fibre ultrafiltration membrane module (ZW-1) was used to treat real GW with the aim of producing effluent that meets reuse guidelines for non-potable standards. A complete retention for activated sludge was maintained in the bioreactor to minimize the amount of sludge disposed into the environment. The results demonstrated that the SMBR system was able to reduce effectively the COD, NH3–N, turbidity, and colour to have values of 45mg/L, 0.26mg/L, 3FTU and 18 PtCo in the effluent, respectively. Furthermore, a complete removal of total suspended solids (TSS) was achieved and faecal coliform concentration was below the determination threshold. In terms of membrane permeability, the results showed that the cake layer contributed significantly (86%) in reducing the permeation flux. The time-dependent permeation flux was modelled adequately according to an exponential expression. Ultimately, the treated GW by SMBR system can be considered as a good source for the most stringent non-potable reuse standards in arid areas.

Highly effective antifouling performance of PVDF/graphene oxide composite membrane in membrane bioreactor (MBR) system

A composite microfiltration membrane, prepared by blending polyvinylidene fluoride (PVDF) and hydrophilic graphene oxide (GO) nanosheets, was successfully used in a submerged membrane bioreactor system. Scanning electron microscopy (SEM), contact angle measurements, and X-ray photoelectron spectroscopy were used to determine the surface properties of GO modified PVDF membrane. To compare the composite membrane with a commercial PVDF membrane, the critical flux, fouling behavior, membrane resistance, and anti-fouling properties against extracellular polymeric substances (EPS) were studied. Higher critical flux was obtained by PVDF/GO composite membrane due to the change of surface characteristics. The PVDF/GO composite membrane demonstrated sustained permeability, lower cleaning frequency, and filtration time that was three times longer than that of the PVDF membrane. In terms of anti-EPS accumulation, the PVDF/GO composite membrane showed lower membrane resistance, particularly, lower pore plugging resistance than the PVDF membrane. Fewer amounts of EPS, specifically polysaccharide accumulated on the composite membrane surface due to the introduction of GO nanosheets. The SEM and confocal laser scanning microscope images showed that the cake layer on composite membrane was looser and thinner than that of commercial PVDF membrane. Consequently, membrane surface was exposed, resulting in the maintenance of high permeability over a long period of time.

The treatment of pharmaceutical wastewater using in a submerged membrane bioreactor under different sludge retention times

The performance of a lab-scale submerged membrane bioreactor system (SMBR) for treating a process wastewater containing the pharmaceutical active compound (PhAc) etodolac with four different microfiltration (MF) membranes (MP005, MV02, CA, and MCE) was investigated at three different sludge retention times (SRTs) under constant pressure. In the first phase of the study, the continuous bioreactor system was operated at SRTs of 15 and 30 days and without sludge wasting (WSW). After steady state conditions were reached, the SMBR process was started as the second phase. Short-term filtration (24h) tests were conducted for each SRT. When the SRTs were increased, both permeate volumes and steady-state flux values increased. The best etodolac removals were obtained in case of WSW for both bioreactor system and SMBR. The etodolac removals achieved by the different membranes for the period WSW were observed in the following order: MV02=MP005>CA=MCE. In addition, the chemical oxygen demand (COD) removal efficiencies for bioreactor system and SMBR were approximately 80±2% and 86±2%, respectively, at all SRTs. The COD removals at each of the three SRTs were similar for all of the membranes. Extracellular polymeric substances (EPSs) and soluble microbial products (SMPs) were analyzed as fouling control factors. Increasing the SRT caused increases in sludge concentrations in the SMBR as well as in increased etodolac removal, while EPS and SMP protein and carbohydrate concentrations decreased. Fouling on the pores and surfaces of the membranes were characterized using a Scanning Electron Microscope (SEM), an Atomic Force Microscope (AFM), a Fourier transform infrared spectroscopy (FT-IR), and contact angle measurements. The resistance in series model was used to evaluate the flux decline caused by the gel layer, cake resistance, and internal pore blocking in the MF membranes at the three different SRTs.

Evaluation of a submerged membrane bioreactor (SMBR) coupled with chlorine disinfection for municipal wastewater treatment and reuse

In this study, municipal wastewater was treated by a SMBR system and further disinfected with chlorine to produce reclaimed water. The primary objective was to examine the water quality with a focus on trihalomethanes (THMs). As disinfection conditions are important aspects in controlling the formation of THMs, influences of chlorine dose and contact time on THM formation and speciation were also investigated. High quality reclaimed water was generated though the SMBR system with regard to five-day biological oxygen demand (BOD5), suspend solid (SS) and turbidity. However the concentration of total trihalomethanes (TTHM) in the chlorinated SMBR effluent was up to 160μg/L, demonstrating that the SMBR was insufficient in the removal of THM precursors. TTHM levels increased with chlorine dose and contact time. As chlorine dose increased, the yields of trichloromethane (CHCl3) and bromodichloromethane (CHBrCl2) increased, whereas both tribromomethane (CHBr3) and dibromochloromethane (CHBr2Cl) decreased due to the rise of Cl2/Br− ratio. In order to reduce health risks of reclaimed water, efficient removal of disinfection by-product precursor and opportune chlorine disinfection conditions are recommended.