The necessity for effective wastewater treatment and purification has grown as a result of the increasing pollution issues brought on by industrial and municipal wastewater. Membrane bioreactor (MBR) ...technology stands out when compared to other treatment methods because of its high efficiency, environmental friendliness, small footprint, and ease of maintenance. However, the development and application of membrane bioreactors has been severely constrained by the higher cost and shorter service life of these devices brought on by membrane biofouling issues resulting from contaminants and bacteria in the water. The nanoscale size of the electrospinning products provides unique microstructure, and the technology facilitates the production of structurally different membranes, or the modification and functionalization of membranes, which makes it possible to solve the membrane fouling problem. Therefore, many current studies have attempted to use electrospinning in MBRs to address membrane fouling and ultimately improve treatment efficacy. Meanwhile, in addition to solving the problem of membrane fouling, the fabrication technology of electrospinning also shows great advantages in constructing thin porous fiber membrane materials with controllable surface wettability and layered structure, which is helpful for the performance enhancement of MBR and expanding innovation. This paper systematically reviews the application and research progress of electrospinning in MBRs. Firstly, the current status of the application of electrospinning technology in various MBRs is introduced, and the relevant measures to solve the membrane fouling based on electrospinning technology are analyzed. Subsequently, some new types of MBRs and new application areas developed with the help of electrospinning technology are introduced. Finally, the limitations and challenges of merging the two technologies are presented, and pertinent recommendations are provided for future research on the use of electrospinning technology in membrane bioreactors.
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•The article reviews the research and application of electrospinning technology in different types of MBRs.•The article analyzes several approaches (including novel membrane design, additional features, and technological innovation) to combat membrane fouling and enhance the performance of MBRs with electrospinning technology.•The article discusses the problems of combining electrospinning technology with MBRs and envisions future research directions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Extensive research in recent years has explored numerous new features in the forward osmosis membrane bioreactor (FOMBR) process. However, there is an aspect, which is revolutionary but not yet been ...investigated. In FOMBR, FO membrane shows high rejection for a wide range of soluble contaminants. As a result, hydraulic retention time (HRT) does not correctly reflect the nominal retention of these dissolved contaminants in the bioreactor. This decoupling of contaminants retention time (CRT, i.e. the nominal retention of the dissolved contaminants) from HRT endows FOMBR a potential in significantly reducing the HRT for wastewater treatment. In this work, we report our results in this unexplored treatment potential. Using real municipal wastewater as feed, both a hybrid microfiltration-forward osmosis membrane bioreactor (MF-FOMBR) and a newly developed hybrid biofilm-forward osmosis membrane bioreactor (BF-FOMBR) achieved high removal of organic matter and nitrogen under HRT of down to 2.0 h, with significantly enhanced phosphorus recovery capacities. In the BF-FOMBR, the used of fixed bed biofilm not only obviated the need of additional solid/liquid separation (e.g. MF) to extract the side-stream for salt accumulation control and phosphorus recovery, but effectively quarantined the biomass from the FO membrane. The absence of MF in the side-stream further allowed suspended growth to be continuously removed from the system, which produced a selection pressure for the predominance of attached growth. As a result, a significant reduction in FO membrane fouling (by 24.7–54.5%) was achieved in the BF-FOMBR due to substantially reduced bacteria deposition and colonization.
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•FO membrane decouples CRT from HRT; HRT can thus be significantly reduced.•Both BF-FOMBR and MF-FOMBR achieved high pollutant removal with HRT of 2 h.•Reduced HRT resulted in enhanced phosphorus recovery capacity in both systems.•The use of fixed-bed biofilm overcame the need for MF in side-stream extraction.•The use of biofilm also significantly lowered FO membrane fouling.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The robustness of anaerobic dynamic membrane bioreactor (AnDMBR) for synthetic textile wastewater treatment was investigated. Textile wastewater may contain high concentrations of NaCl and sulfate, ...hence their impact on the AnDMBR performance was investigated in detail. A dynamic membrane was formed on a 20-μm pore sized nylon support layer at a constant flux of around 8 LMH. In the absence of sulfate addition, total and filtered (soluble) COD averaged 96 ± 49 mg/L (91% removal) and 75 ± 35 mg/L (93% removal), respectively. Sulfate addition increased total COD in the permeate to 222 ± 68 mg/L (79% removal). Average SS concentration was lower than 30 mg/L in the permeate although its concentration in the bioreactor reached 10 g/L. Throughout the AnDMBR operation dye removal averaged >97%. Sludge filterability, which was assessed by specific resistance to filtration, supernatant filtration, capillary suction time and viscosity, decreased after sulfate addition. Organic and inorganic matters in the dynamic layer were characterized by SEM-EDS and FTIR analyses.
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•Dynamic membrane filtration in the treatment of textile effluent was investigated.•Dynamic MBR was operated at a constant flux of 8 LMH.•Over 97% dye removal was achieved while influent dye was between 100 and 200 mg/L.•Effluent suspended solid concentration was below 30 mg/L throughout the study.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Very first review on MBR technologies for tannery wastewater (TWW) treatment.•Among various MBR moving bed biofilm bioreactor (MBBR) was found most effective for TWW treatment.•MBBR showed great ...efficiency in reducing COD and salinity from TWW.•Appropriate modification of MBBR may lead sustainability of tannery effluent treatment plant.
A multitude of tannery wastewater (TWW) is a key challenge for the tanning industry. Developing efficient and new technology is crucial to regulate the disposal of TWW. Many scientists developed a variety of types of membrane bioreactor-based technologies to treat TWW. This study performed a critical review to understand the existing membrane bioreactor-based TWW treatment technologies. The review revealed that many studies tried to understand the removal efficiency of the membrane bioreactor-based technologies for treating TWW. The study findings depicted that scientists tried to develop various types of membrane technologies, i.e., modified membrane bioreactor (MBR), anaerobic MBR, moving bed biofilm bioreactor (MBBR) and hybrid MBBR, osmotic membrane bioreactor (OMBBR), hybrid MBR. The MBBR technologies performed better than the existing MBR techniques among the currently employed MBR. The review suggests a set of future research domains for sustainable treatment of TWW by applying MBR. In the future, the research focus could be on the development of novel biocarriers, application of 3D printing and the implementation of process simulation to enhance process efficiency and sustainability. . The review will aid scientists in enhancing their comprehension of the processes associated with different MBR treatment technologies used for treating TWW. This will, in turn, accelerate the advancement of process parameters and techniques.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Advanced oxidation processes have been widely applied as a post-treatment solution to remove residual organic compounds in water reuse schemes. However, UV/TiO2 photocatalysis, which provides a ...sustainable option with no continuous chemical addition, has very rarely been studied to treat anaerobically treated effluents. In the current study, the removal of organics and nutrients from an anaerobic membrane bioreactor (AnMBR) effluent is evaluated during adsorption and photocatalysis processes under various conditions of TiO2 dose and UV intensity and compared to the effluent from an aerobic membrane bioreactor (AeMBR). The sequence for preferential adsorption on TiO2 was found to be phosphorus, inorganic carbon and then ammonia/organic carbon were found. The competing effect between the organics and nutrients, along with the low UV transmission efficiency caused by the need for high doses of TiO2, ultimately compromise the organic removal efficiency in the AnMBR permeate. TiO2 dosage was found to have a greater impact than UV intensity on improving the overall removal performance as nutrients are competing for the adsorption site but are not photodegraded. Under the same operational condition, the UV/TiO2 photocatalysis displayed a higher removal efficiency of organic matter and phosphorus in the AeMBR effluent due to a lower initial organics concentration and absence of ammonia as compared to the AnMBR effluent.
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•Adsorption priority on TiO2 is phosphorus, inorganic carbon, ammonia/organic carbon.•Only organic compounds were found to be photodegraded by UV/TiO2.•Ammonia and phosphorus are adsorbed but not degraded.•Competing effects between nutrients and organics lead to increased catalyst dosage.•UV/TiO2 displayed non-selectivity for all dissolved organic matter fractions removal.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Recent challenges in MBR and electrochemical processes are discussed.•New configurations of MBR and electrochemical reactors are examined.•Removal of organics, heavy metal ions, micropollutants, and ...dyes are analyzed.•Low-voltage electrically-enhanced MBRs address the drawbacks of standalone units.•Future prospects are discussed.
Research and development activities on standalone systems of membrane bioreactors and electrochemical reactors for wastewater treatment have been intensified recently. However, several challenges are still being faced during the operation of these reactors. The current challenges associated with the operation of standalone MBR and electrochemical reactors include: membrane fouling in MBR, set-backs from operational errors and conditions, energy consumption in electrochemical systems, high cost requirement, and the need for simplified models. The advantage of this review is to present the most critical challenges and opportunities. These challenges have necessitated the design of MBR derivatives such as anaerobic MBR (AnMBR), osmotic MBR (OMBR), biofilm MBR (BF-MBR), membrane aerated biofilm reactor (MABR), and magnetically-enhanced systems. Likewise, electrochemical reactors with different configurations such as parallel, cylindrical, rotating impeller-electrode, packed bed, and moving particle configurations have emerged. One of the most effective approaches towards reducing energy consumption and membrane fouling rate is the integration of MBR with low-voltage electrochemical processes in an electrically-enhanced membrane bioreactor (eMBR). Meanwhile, research on eMBR modeling and sludge reuse is limited. Future trends should focus on novel/fresh concepts such as electrically-enhanced AnMBRs, electrically-enhanced OMBRs, and coupled systems with microbial fuel cells to further improve energy efficiency and effluent quality.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The organic loading rate (OLR) is an essential parameter that controls the anaerobic digestion process. This work investigated the performance of immersed membrane bioreactors operated at high OLRs ...of 4, 6, 8 and 10 g volatile solids (VS)/L/d regarding the fermentation behavior, product recovery and microbial dynamics during the acidogenic fermentation of food waste to volatile fatty acids (VFAs) and hydrogen. The highest yield of 0.52 g VFA/gVSadded was attained at 6 g VS/L/d, while an optimal hydrogen yield of 14.7 NmL/gVSadded was obtained at 8 g VS/L/d. The bacterial populations, analyzed using 16S rRNA gene amplicon sequencing, consisted mainly of Firmicutes and Actinobacteria at OLRs 4 and 8 g VS/L/d while Firmicutes, Actinobacteria and Proteobacteria phyla dominated at 6 and 10 g VS/L/d. Moreover, the presence of Clostridium and Lactobacillus genera correlated with the acetate, butyrate, caproate and lactate production.
•Production of VFAs and hydrogen in membrane bioreactors at high OLRs was assessed.•The OLR of 6 g VS/L/d resulted in the highest yield of VFAs at 0.52 gVFA/gVSadded.•The OLR of 8 g VS/L/d resulted in the highest yield of hydrogen at 14.7 NmL/gVSadded.•Dominance of acetate, butyrate and caproate was due to the presence of Clostridium.•Relative abundance of Lactobacillus influenced the biosynthesis of lactate.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Aerobic granular sludge membrane bioreactor (AGMBR) has emerged with strong potential to overcome membrane fouling. There have been no extensive studies on extracellular polymeric substances (EPS) in ...AGMBR. The present work aimed at conducting an in-depth study of EPS and monitoring fouling development in AGMBR using a 22 factorial design having hydraulic retention time (HRT) and total organic carbon (TOC) as independent variables. HRT was tested at three levels of 6, 8 and 10 h while the TOC levels were 104 ± 13, 189 ± 17, and 266 ± 27 mg/L. AGMBR exhibited high proteins (PN) in the tightly-bound EPS (TB-EPS) resulting in high proteins/polysaccharides (PN/PS) ratios of 2–16. The PN in the LB-EPS was low, ranging from 0.01 to 1.92 mg/g MLVSS, but the range of PN/PS ratio was also of 2–16. Despite the high PN/PS ratio, TMP rise was low. Water jet easily sloughed off the developed membrane cake layer. The elimination of chemicals for membrane cleaning has significant cost savings. TOC had a significant main effect on both the PN and PS components of TB-EPS at α < 0.05. TB-EPS PN increased with increase in TOC. TB-EPS PN decreased as HRT increased from 6 h to 10 h at 104 ± 13 mg/L TOC but the change of HRT from 10 h to 6 h at 266 ± 27 mg/L TOC did not affect TB-EPS PN. The TMP increased with increasing HRT at 104 ± 13 and 266 ± 27 mg/L TOC. An increase in sEPS PN correlated well with increase in membrane fouling (r = 0.581). Three runs performed best: 266 ± 27 mg/L TOC and 10 h HRT; 104 ± 13 mg/L TOC and 6 h HRT; and 266 ± 27 mg/L TOC and 6 h HRT as TMP was below the 50 kPa threshold. AGMBR achieved 98 ± 1%, 99 ± 1%, 52 ± 33% organics degradation, NH3-N removal, total nitrogen removal, respectively.
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•AGMBR exhibited high PN/PS ratio (2–16) for LB-EPS and TB-EPS.•3D-EEM confirm PN to be the most significant component of TB-EPS.•Low membrane fouling with no membrane cleaning in 3 of the 5 runs.•No chemical cleaning required as water jet easily sloughed off membrane cake layer.•AGMBR achieved excellent TOC and NH3-N removal but limited TN removal.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Integration of AnMBR with bioelectrochemical processes benefit for MWW treatment.•MEC-AnMBR can heighten biomass conversion capacity and decrease membrane fouling.•MEC-AnMBR facilitates exocellular ...electron transfer and bacteria activity.•Voltage, hydraulic retention time, temperature and module material require concern.•Future development to enhance matter conversion and energy recovery are proposed.
The coupling of membrane separation technology with anaerobic digestion (AD) treatment in anaerobic membrane bioreactors (AnMBRs) presents a promising approach for municipal wastewater (MWW) treatment, offering exceptional treatment efficiency and the potential to recover valuable bioenergy resources. However, challenges like suboptimal methane production efficiency, refractory substances inhibition, and issues related to membrane fouling pose significant obstacles to the use of AnMBRs in full-scale MWW treatment. In recent years, the combination of AnMBR with bioelectrochemical processes, such as microbial electrolysis cell (MEC), holds great potential to address these challenges, but a systematic analysis is currently lacking. Herein, this study systematically reviewed the enhancement of bioelectrochemical processes in AnMBRs for MWW treatment. We initially identified the primary challenges associated with AnMBR in MWW treatment. On this basis, we described the different integration of MEC with AnMBR (MEC-AnMBR) configurations and highlighted the advantages of MEC-AnMBR technology in treating MWW, including heightened biomass conversion capacity, mitigated substance inhibition and decreased membrane fouling, particularly in low temperature and low organic substrate conditions. The effects of various operating parameters in MEC-AnMBRs treatments, including reactor type, applied voltage, hydraulic retention time (HRT), temperature, and module material were also detailed. Furthermore, we elucidated the mechanisms of the bioelectrochemical processes in MEC-AnMBRs to overcome the limitations of AnMBRs in treating MWW. By accelerating exocellular electron transfer and boosting the activity of electroactive microorganisms (EAMs), the bioelectrochemical processes in AnMBRs are able to improve methane production, eliminate refractory organic matter, and regulate membrane fouling. Finally, this study explored the potential future development of MEC-AnMBRs to enhance material conversion and energy recovery, ultimately promoting a circular economy in the wastewater treatment industry.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Thermophilic membrane bioreactor technologies are systematically reviewed.•Thermophilic membrane bioreactor technologies have a number of advantages.•Membrane fouling is the major challenge for ...thermophilic membrane bioreactor applications.•Challenges and opportunities of thermophilic membrane bioreactors are identified.
This study undertakes a state-of-the-art review on thermophilic membrane bioreactors (ThMBRs). Thermophilic aerobic membrane bioreactors (ThAeMBR) and thermophilic anaerobic membrane bioreactors (ThAnMBR) have been widely tested for various high-temperature industrial wastewater treatments at lab- and pilot-scale studies and full-scale applications. The biological and membrane performances of the ThAeMBRs and ThAnMBRs could be better, comparable or poorer, as compared to the mesophilic ones. In general, sludge yield was much lower, biodegradation kinetic was higher, and microbial community was less diversity in the ThAeMBR and ThAnMBR systems. The results from the literature show that ThMBR technology has demonstrated many advantages and is a promising technology for industrial wastewater treatment and sludge digestion. Furthermore, challenges and opportunities of various ThMBRs for industrial applications are identified and discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
