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The use of membrane bioreactors (MBR) is a promising technique for wastewater treatment that manages to respect the restrictive limits imposed by regulations. However, during the filtration process membranes are subject to fouling which requires additional costs for cleaning and replacing the modules. This phenomenon severely limits the widespread of this technology on a real scale. Thanks to many scientific studies, it has been possible to put into practice various fouling mitigation strategies which, at the same time, manage to increase the treatment efficiencies of the system, such as the application of electrochemical processes associated with MBR reactors (e-MBR). The introduction of low-cost self-forming dynamic membranes (SFDM), to replace the conventional ones, has made MBR technology even more promising. However, the large size of the pores limits their application since the effluents obtained at the beginning of the process are not of good quality. In the present study the performance of an innovative patented hybrid reactor, which combines encapsulated self-forming dynamic membranes (ESFDM) with an electro-MBR, was studied. The experiment, conducted at a pilot scale using real wastewater from a full-scale wastewater treatment plant, evaluated the efficiency of pollutant removal and fouling formation as a function of the applied current density.

Introduction Self-forming dynamic membrane (SFDM) technology has been gaining significant interest due to its potential advantages, notably lower capital and operational cost and easier fouling con...

The concept of a novel living encapsulated self-forming dynamic bio-membranes (ESFDM) for an innovative wastewater treatment in membrane bioreactor (MBR) is presented in the current study. The active filtering membrane is encapsulated, and thus stabilized, between two support meshes with pore in micrometer size. The combination of activated sludge, the ESFDM and the cake layer formed external to the filtering module contributed to the treatment of municipal wastewater. COD concentration reductions (average value of 95.55 ± 1.44%) by ESFDM bioreactor (ESFDMBR) were comparable to those obtained with a previously reported membrane bioreactor (MBR), where a conventional membrane was studied under the same operating conditions. The ESFDMBR, compared to the conventional MBR, obtained higher reductions of NH3-N, NO3–N and PO43–P concentrations. Increased removals of nitrogen-containing nutrients were ascribed to anoxic conditions reached in the ESFDM layer protected from the aeration by the external cake layer. Rate of increase of transmembrane pressure (TMP) per day in the ESFDMBR (0.03 kPa/day) was lower than the value obtained in the previously reported conventional MBR (8.08 kPa/day). Lower concentrations of fouling precursors in combination with the effective filtration capacity of the porous living ESFDM resulted in the reduction of the fouling rate. Analysis of microbiological community revealed that the microbial community structures in the mixed liquor and ESFDM were different. The ESFDM layer promoted growth of bacteria as indicated by the higher total cell count and higher microbial diversity compared to those observed in the mixed liquor.

The effect of addition of algae to activated sludge as active biomass in membrane bioreactors (MBRs) and electro-MBRs (e-MBRs) for wastewater remediation was examined in this study. The performances of Algae-Activated Sludge Membrane Bioreactor (AAS-MBR) and electro Algae-Activated Sludge Membrane Bioreactor (e-AAS-MBR) were compared to those observed in conventional MBR and e-MBR, which were previously reported and utilized activated sludge as biomass. The effect of application of electric field was also examined by the comparison of performances of e-AAS-MBR and AAS-MBR. Similar chemical oxygen demand (COD) reduction efficiencies of AAS-MBR, e-AAS-MBR, MBR, and e-MBR (98.35 ± 0.35%, 99.12 ± 0.08%, 97.70 ± 1.10%, and 98.10 ± 1.70%, respectively) were observed. The effect of the algae-activated sludge system was significantly higher in the nutrient removals. Ammoniacal nitrogen (NH3−N) removal efficiencies of AAS-MBR and e-AAS-MBR were higher by 43.89% and 26.61% than in the conventional MBR and e-MBR, respectively. Phosphate phosphorous (PO43−-P) removals were also higher in AAS-MBR and e-AAS-MBR by 6.43% and 2.66% than those in conventional MBR and e-MBR. Membrane fouling rates in AAS-MBR and e-AAS-MBR were lower by 57.30% and 61.95% than in MBR and e-MBR, respectively. Lower concentrations of fouling substances were also observed in the reactors containing algae-activated sludge biomass. Results revealed that addition of algae improved nutrient removal and membrane fouling mitigation. The study also highlighted that the application of electric field in the e-AAS-MBR enhanced organic contaminants and nutrients removal, and fouling rate reduction.

The low-level presence of emerging contaminants (ECs) in the environment has raised a great concern due to their persistence, chronic toxicological, and endocrine disrupting effects on terrestrial and aquatic organisms. Wastewater treatment plants (WWTPs) have become hotspots for the spread of these contaminants to the environment as conventional processes are not efficient in removing them. Thus, the integration of advanced treatment methods within the chain of WWTPs is very essential. In this study, the innovative hybrid process USAMe® which integrates ultrasound irradiation (US), adsorption (A) and membrane filtration (Me) was investigated for the removal of ECs from secondary effluents. Diclofenac, carbamazepine, and amoxicillin were selected due to their large consumption and frequent presence in the aquatic environment. All three ECs were spiked into real secondary wastewater effluent at two concentrations of 10 ppm and 100 ppb. Membrane ultrafiltration and its combination with US (USMe) or adsorption (AMe) were also studied as control tests. The hybrid combination of all the three methods in the USAMe® processes elevated the EC removals to above 99% as compared to only around 90% in the AMe process. All effluents of the hybrid USAMe® processes gave “No Effect” to D. magna, with immobilization of ≤20%. Therefore, results showed that the USAMe® process was efficient in not only removing ECs, but also in generating safe and less toxic treated effluents; thereby displaying its potential as an advanced method for wastewater treatment.

Presence of organic micropollutants (OMP) in wastewater has become an emerging concern due to OMP's bioaccumulation capacity in the aquatic environment and their harmful effects. As a result, numerous processes have been explored as alternatives to conventional activated sludge (CAS) to address OMP removal. Among these, membrane bioreactor (MBR) has become a promising option due to its capacity to retain high microorganism concentration and produce high effluent quality with low sludge production. MBR has been proven effective in OMP removal. Nonetheless, recalcitrance of other OMPs and membrane fouling limited MBR efficiency. Integration of MBR with other processes such as advanced oxidation, ozonation, adsorption, reverse osmosis, and electrochemical processes increased MBR efficiency while quorum sensing (QS) inhibition through quorum quenching (QQ) was proven effective in membrane fouling mitigation.

Water and energy are two essential resources for our future since these two resources are strongly interconnected. The identification of the future scenarios and the evaluation of the possible impact on the water sector due the production of electricity are essential actions to be performed in order to obtain a picture of possible developments that could affect the national and the international energy scenarios.

This paper presents self-forming dynamic membrane (SFDM) process as a promising alternative to membrane technology. A stable dynamic membrane (DM) is mainly composed of gel layer and cake layer which are responsible for filtration and biodegradation. An understanding of the formation mechanism and impact of operating conditions, support mesh, sludge properties and configuration on the formation, and characteristics of the dynamic membrane is essential to optimize the efficiency and reduce fouling propensity of this technology. The paper thus aims to promote its applicability on wastewater treatment. Review of the influence of mesh support properties, different operating conditions and sludge properties on SFDM performance, and cost comparison between MBR and SFDMBR technologies.

This paper focused on the combination of membrane ultrafiltration, adsorption and ultrasound processes in one hybrid process called USAMe for improving membrane wastewater treatment performance and membrane fouling control. Different tests were conducted at different ultrasound frequencies and recycle ratio. Improved permeate quality in the USAMe process. Membrane fouling reduction with the combined application of ultrasound and activated carbon. Influence of ultrasound frequency, membrane flux and recycle ratio on treatment performance.

Membrane bioreactor (MBR) technology is becoming increasingly popular as wastewater treatment due to the unique advantages it offers. However, membrane fouling is being given a great deal of attention so as to improve the performance of this type of technology. Recent studies have proven that the application of electrochemical processes to MBR represents a promising technological approach for membrane fouling control. In this work, two intermittent voltage gradients of 1 and 3 V/cm were applied between two cylindrical perforated electrodes, immersed around a membrane module, at laboratory scale with the aim of investigating the treatment performance and membrane fouling formation. For comparison purposes, the reactor also operated as a conventional MBR. Mechanisms of nutrient removal were studied and membrane fouling formation evaluated in terms of transmembrane pressure variation over time and sludge relative hydrophobicity. Furthermore, the impact of electrochemical processes on transparent exopolymeric particles (TEP), proposed as a new membrane fouling precursor, was investigated in addition to conventional fouling precursors such as bound extracellular polymeric substances (bEPS) and soluble microbial products (SMP). All the results indicate that the integration of electrochemical processes into a MBR has the advantage of improving the treatment performance especially in terms of nutrient removal, with an enhancement of orthophosphate (PO4-P) and ammonia nitrogen (NH4-N) removal efficiencies up to 96.06 and 69.34 %, respectively. A reduction of membrane fouling was also observed with an increase of floc hydrophobicity to 71.72 %, a decrease of membrane fouling precursor concentrations, and, thus, of membrane fouling rates up to 54.33 %. The relationship found between TEP concentration and membrane fouling rate after the application of electrochemical processes confirms the applicability of this parameter as a new membrane fouling indicator.

Pharmaceutical active compounds (PhACs) have been detected at significant concentrations in various natural and artificial aquatic environments. In this study, electro membrane bioreactor (eMBR) technology was used to treat simulated municipal wastewater containing widely-used pharmaceuticals namely amoxicillin (AMX), diclofenac (DCF) and carbamazepine (CBZ). The effects of varying current density on the removal of PhACs (AMX, DCF and CBZ) and conventional pollutants (chemical oxygen demand (COD), dissolved organic carbon (DOC), humic substances, ammonia nitrogen (NH4-N), nitrate nitrogen (NO3-N) and orthophosphate (PO4-P) species) were examined. High COD and DOC removal efficiencies (~100%) were obtained in all the experimental runs regardless of applied current density. In contrast, enhanced removal efficiencies for AMX, DCF and CBZ were achieved at high current densities. Membrane fouling rate in eMBR with respect to conventional MBR was reduced by 24, 44 and 45% at current densities of 0.3, 0.5 and 1.15 mA/cm2, respectively. The mechanism for pharmaceutical removal in this study proceeded by: (1) charge neutralization between negatively-charged pharmaceutical compounds and positive electro-generated aluminium coagulants to form larger particles and (2) size exclusion by membrane filtration.

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.

Membrane bioreactors (MBRs) are a well established and mature technology with many full-scale plants around the world treating municipal and industrial wastewater (Krzeminski et al. in J. Membr. Sci. 527:207–227, 2017).

In this study, the viability of using electrocoagulation process as a method for pharmaceuticals removal from real municipal wastewater was demonstrated. Batch experimental runs were performed using a simple laboratory scale electrochemical reactor with aluminium and stainless steel as anode and cathode, respectively. Diclofenac (DCF), carbamazepine (CBZ) and amoxicillin (AMX) were selected as representative of pharmaceuticals frequently detected in the aquatic environment. The effects of varying experimental parameters namely current density (0.3, 0.5 1.15 and 1.8 mA cm−2), initial pharmaceutical concentration (0.01, 4 and 10 mg L-1), electrolysis duration (3, 6 and 19 h) and application mode (continuous vs. intermittent) on pharmaceutical removal efficiencies were evaluated. High pharmaceutical abatement was recorded at elevated current density and prolonged electrolysis duration due to additional electro-generated coagulant species in solution.

The present study investigated the influence of electric field on the removal of quorum sensing (QS) and emerging contaminants using an electrochemical membrane bioreactor (eMBR). A significant reduction of N-octanoyl-L-homoserine lactone signal molecules (∼76%) was achieved in the eMBR, with respect to the level observed in the conventional MBR as the control. Furthermore, the intermittent electric current supply (0.5 mA/cm2) was found to be effective for the removal of atrazine and estrone. The degradation of key pharmaceutical compounds, such as diclofenac, carbamazepine, and amoxicillin, was also possible, confirming the applicability of the eMBR system for removing the priority chemical compounds of public health concern.

Membrane bioreactor (MBR) is a reliable and promising technology for wastewater treatment and reuse. However, since membrane fouling and energy consumption still remain operational obstacles and challenges for the widespread application of the MBR technology, research studies for fouling control are still underway. Recently, among different integrated approaches for membrane fouling mitigation, the combinations of MBRs with electrochemical processes (eMBR/electro MBR) or with moving bed biofilm reactor (MBBR) have been adopted as alternative technological methods. In the present study, the performance of an electro moving bed membrane bioreactor (eMB-MBR), in terms of treatment efficiency and fouling formation, was investigated as a novel integrated process which combines an electro MBR with a moving bed membrane bioreactor (MB-MBR). An intermittent voltage gradient of 3 V/cm was applied between two electrodes immersed around a membrane module inside the bioreactor filled with carriers at 30% filling ratio. A MB-MBR was operated as a control test. The integration of electrochemical processes into the MB-MBR improved the treatment performance especially in terms of nutrient removal, with an enhancement of orthophosphate (PO4-P) and ammonia nitrogen (NH4-N) removal efficiencies up to 55.0% and 98.7%. The filtration cycles were extended in the eMB-MBR with a reduction of membrane fouling rate of around 60% and of membrane fouling precursors respect to the control test. The results obtained showed the synergic effect of the combined process. Hence, the eMB-MBR process represents a novel exciting technology which is deemed possible for wastewater treatment.

Recently, microbial fuel cells (MFCs) have been integrated with membrane bioreactors (MBRs), either in an internal or an external configuration, for wastewater treatment and energy recovery. In an external configuration, MFCs could be applied for an efficient sludge reduction since they can simultaneously address energy issue and environmental concerns associated with sludge treatment. In the present study, a potentiostatic controlled microbial fuel cell (MFC) was fed with activated sludge from a membrane bioreactor (MBR) at different total suspended solid (TSS) concentrations (1–10 gTSS L −1 ) in order to assess the electrochemical response of the system and the impact of the bioelectrochemical treatment on sludge characteristics and membrane fouling parameters. The MFC showed COD removals 30% higher than the control test and a reduction of volatile suspended solids (VSS) up to 43% with concomitant production of energy (maximum current density of 2.0 A m −2 ). The electricity production increased with the increase of TSS content. In both MFC and the control test, an increase of soluble microbial products (SMP) ratio in terms of proteins and carbohydrates (SMPp/SMPc) and an average 50% increase of sludge hydrophobicity were observed. This could limit membrane fouling in the case that the sludge is recirculated to the MBR. The electrochemical characterization indicated that both, acetate and sludge oxidation took place at a similar formal potential of −0.2 V vs. SHE indicating that both used the same electron transfer mechanism. Hence, this study shows that a MFC could oxidize, reduce and stabilise MBR sludge producing electricity and affecting membrane fouling parameters The authors would like to thank the Spanish Ministry (CTQ2014-53718-R and CTM2015-71982-REDT) and the University of Girona (MPCUdG2016/137) for their financial support. LEQUIA has been recognised as consolidated research groups by the Catalan Government (2014-SGR-1168)

The continuous release of emerging contaminants (ECs) in the aquatic environment, as a result of the inadequate removal by conventional treatment methods, has prompted research to explore viable solutions to this rising global problem. One promising alternative is the use of electrochemical processes since they represent a simple and highly efficient technology with less footprint. In this paper, the feasibility of treating ECs (i.e., pharmaceuticals) using an intermittent electrocoagulation process, a known electrochemical technology, has been investigated. Diclofenac (DCF), carbamazepine (CBZ) and amoxicillin (AMX) were chosen as being representative of highly consumed drugs that are frequently detected in our water resources and were added in synthetic municipal wastewater. The removal efficiencies of both individual and combined pharmaceuticals were determined under different experimental conditions: hydraulic retention time (HRT) (6, 19 and 38 h), initial concentration (0.01, 4 and 10 mg/L) and intermittent application (5 min ON/20 min OFF) of current density (0.5, 1.15 and 1.8 mA/cm2). Results have shown that these parameters have significant effects on pharmaceutical degradation. Maximum removals (DCF = 90%, CBZ = 70% and AMX = 77%) were obtained at a current density of 0.5 mA/cm2, an initial concentration of 10 mg/L and HRT of 38 h.

The combination of chemical and biological treatment is a promising solution to remove emerging contaminants, e.g., pharmaceuticals, from wastewater for its future reuse. In this study, the combination of ozonation and ultrasound (O3/US) was examined as a pretreatment prior to membrane bioreactor (MBR). The effects of O3/US on the removal of selected pharmaceuticals, including diclofenac (DCF), sulfamethoxazole (SMX) and carbamazepine (CBZ), and MBR fouling control were investigated. The variation of the toxicity potential of the MBR influent was also assessed. The O3/US treatment was effective in reducing fouling, mainly due to its effects on the microbial metabolism products in the MBR. Extracellular polymeric substance (EPS) concentration was reduced by 50%. Improved operating conditions resulted in higher removal rates for pharmaceuticals in the MBR effluent, with removal efficiency in the range of 80–84%. However, the O3/US treatment alone was not efficient in removing the toxicity of wastewater. This was likely due to the formation of intermediate products that are more toxic than the parent compounds. These intermediate products were observed to be biologically oxidized by MBR, with a 80% reduction of the toxicity potential in the MBR permeate compared to the influent.

This study investigates the removal of selected pharmaceuticals, as recalcitrant organic compounds, from synthetic wastewater using an electro-membrane bioreactor (eMBR). Diclofenac (DCF), carbamazepine (CBZ), and amoxicillin (AMX) were selected as representative drugs from three different therapeutic groups such as anti-inflammatory, anti-epileptic, and antibiotic, respectively. An environmentally relevant concentration (10 μg/L) of each compound was spiked into the synthetic wastewater, and then, the impact of appending electric field on the control of membrane fouling and the removal of conventional contaminants and pharmaceutical micropollutants were assessed. A conventional membrane bioreactor (MBR) was operated as a control test. A reduction of membrane fouling was observed in the eMBR with a 44% decrease of the fouling rate and a reduction of membrane fouling precursors. Humic substances (UV254), ammonia nitrogen (NH4-N), and orthophosphate (PO4-P) showed in eMBR removal efficiencies up to 90.68 ± 4.37, 72.10 ± 13.06, and 100%, respectively, higher than those observed in the MBR. A reduction of DCF, CBZ, and AMX equal to 75.25 ± 8.79, 73.84 ± 9.24, and 72.12 ± 10.11%, respectively, was found in the eMBR due to the enhanced effects brought by electrochemical processes, such as electrocoagulation, electrophoresis, and electrooxidation.

The increasing application of membrane filtration in water and wastewater treatment necessitates techniques to improve performance, especially in fouling control. Ultrasound is one promising technology for this purpose as cavitational effects facilitate continuous cleaning of the membrane. This research studied the ultrafiltration of lake water in systems with constant permeate flux under medium frequency (45 kHz) ultrasound irradiation. Fouling was investigated by monitoring transmembrane pressure (TMP) using continuous or intermittent ultrasound irradiation and dead-end or crossflow operation. Best performance was observed with continuous ultrasound irradiation in crossflow mode. Intermittent irradiation reduced the rate of TMP build-up but nevertheless allowed irreversible fouling to develop.

Water scarcity is an increasing world-wide concern due to the rapid growth of population along with industrialization and urbanization. Membrane ultrafiltration represents a promising and sustainable technology for handling this problem through water reuse. However, fouling is still a significant drawback that limits the expansion of membrane filtration use. Recent studies have shown that ultrasound provides an alternative technology for membrane fouling control able to enhance the effluent water quality in an environmentally benign manner. Nevertheless, the ultrasonic parameters affecting the efficiency of the US-enhanced cleaning are not completely well known. In this work results from an experimental study of ultrasonically assisted ultrafiltration, varying ultrasonic frequencies, are presented. The performances of sonochemical oxidation, membrane ultrafiltration and their combination were evaluated on wastewater samples. Results show that ultrasonic field can drastically reduce membrane fouling. It was found that lower frequency (35 kHz) slows down the fouling formation, but, on the other hand, higher frequency (130 kHz) improves the organic matter removal.