Submerged Membrane Electro-bioreactor Research Articles

Enhancement of wastewater nutrient removal at low carbon/nitrogen ratio using a submerged membrane electro-bioreactor

The objective of this research was to explore the feasibility of removing ammonium and nitrate in a single electro-bioreactor at low carbon concentration. For that purpose a submerged membrane electro-bioreactor was operated at three influent carbon/nitrogen ratios (3:1, 2:1 and 1:1). For each carbon/nitrogen ratio, a submerged membrane electro-bioreactor and a membrane bioreactor were operated at the same conditions for 60 days. Results showed that the submerged membrane electro-bioreactor successfully removed ammonium and nitrate at all carbon/nitrogen ratios over membrane bioreactor. At carbon/nitrogen ratio of 1:1, the submerged membrane electro-bioreactor exhibited 9%, 55% and 25% higher removal efficiency over membrane bioreactor for ammonium, nitrate and total nitrogen, respectively. At carbon/nitrogen ratio of 3:1, the submerged membrane electro-bioreactor exhibited 0.0%, 89% and 14% higher removal efficiency over membrane bioreactor for ammonium, nitrate and total nitrogen, respectively. Submerged membrane electro-bioreactor system showed its capacity to remove ammonium, nitrate and total nitrogen regardless of carbon/nitrogen ratio. Submerged membrane electro-bioreactor capacity to remove nitrogen components is feasible because the system can be electrically controlled to operate at alternative aerobic/anaerobic conditions. The efficiency of the submerged membrane electro-bioreactor to remove nitrogen components was found to enhance over time, even though carbon is at low concentration, as higher concentrations of anammox bacteria are built up in the system. Beside nitrogen removal, submerged membrane electro-bioreactor showed on average more than 90% removal of orthophosphate.

Aluminum accumulation in treatment using submerged membrane electro-bioreactor of young landfill leachate: Statistical analysis

Herein, landfill leachate containing high amount of organic matter, which is quite difficult to treat, was first treated using the new submerged membrane electro-bioreactor (SMEBR) system. Aluminum (Al) electrode was used for the treatment of leachate in the SMEBR and Al accumulation was detected. This study aims to examine Al accumulation in the treatment of leachate with high organic content in the SMEBR system. The Al values obtained were plotted on a graph using MS Excel, and Mann–Whitney U test was used to determine whether there is a statistical difference between the observed Al values. Also, correlations between Al accumulations and conductivity and TOC in SMEBR and SMBR were evaluated. Resultantly, it was found that relationship between Al and conductivity is very weak, correlation between Al and TOC% is a weak-moderate, the Al accumulation in the SEMBR has a linear relationship with time and there is a very strong correlation between the two variables (R2= 0.7591). Its correlation with time in the SMBR is moderate (R2= 0.3316). MS Excel 2016 and Minitab 16.0 programs were utilized in the statistical analyses.

Determination of the optimal electrocoagulation operational conditions for pollutant removal and filterability improvement during the treatment of municipal wastewater

This study aims to determine optimal electrocoagulation (EC) operational conditions for removal of nutrients and organic matter and improving the mixed liquor filterability during municipal wastewater treatment in a Submerged Membrane Electro-Bioreactor (SMEBR). First, the optimal electric-current exposure time for the removal of PO4-3-P, NH4+-N, and chemical oxygen demand (COD) was determined. Then, different EC conditions were tested by varying the current density, mode of exposure, and pH, using a factorial design. Finally, the impact of the optimal conditions on biomass activity was evaluated. The observed optimal operational conditions were a current density of 10 Am-2 with an exposure mode of 6'ON/30'OFF at pH 8. Using these optimal conditions, electrocoagulation achieved high removal efficiencies of 99.51%, 98.56%, and 99.04% for PO4-3-P, NH4+-N, and COD, respectively, after 48 hours of treatment. An increase in the size of the flocs, under these optimal conditions, improved filterability to 98.76%, which reduces membrane fouling in an SMEBR. In addition, the optimized conditions increased the autotrophic and heterotrophic oxygen uptake rate, demonstrating that EC can be applied in an SMEBR without reducing the biomass activity.

Quorum sensing control and wastewater treatment in quorum quenching/ submerged membrane electro-bioreactor (SMEBR(QQ)) hybrid system

Membrane biofouling, in terms of quorum sensing (QS), reduction with hollow cylindrical quorum quenching (QQ) beads in submerged membrane bioreactor (SMBR(QQ)) and submerged membrane electro-bioreactor (SMEBR(QQ)) was investigated. Results showed that the rate of pressure increase (i.e. dTMP dt−1) was 0.7 and 0.5 kPa d−1 in SMBR(QQ) and SMEBR(QQ), respectively. Furthermore, sludge physicochemical and biological characteristics were analyzed in terms of mixed liquor suspended solids (MLSS), sludge volume index (SVI), time to filter (TTF), and mean sludge particle size (PSD). Results showed that the presence of electric field reduced SVI and TTF in the SMEBR(QQ) by 47 and 26%, respectively. Also, the concentration profiles of loosely bound extracellular polymeric substances (LB-EPS) and tightly bound EPS (TB-EPS) showed superiority in the performance of SMEBR(QQ) over SMBR(QQ). Chemical oxygen demand (COD) and nutrient removals were higher in the SMEBR(QQ) reporting 97, 90 and 90% removal of COD, ammonium-N (NH4+-N) and phosphorus-P (PO43--P), respectively. The synergetic effects of QQ and electric field have shown significant improvements of conventional MBRs and could be further developed as an efficient wastewater treatment and water reuse.

Optimized coupling of a submerged membrane electro-bioreactor with pre-anaerobic reactors containing anode electrodes for wastewater treatment and fouling reduction

In this paper, the performance of a submerged membrane electro-bioreactor with pre-anaerobic reactors containing anode electrodes (SMEBR+) was compared with that of a membrane bioreactor (MBR) in municipal wastewater treatment. The new design idea of the SMEBR+ was based on applications of direct current (DC) on the anode and cathode electrodes. The pilot study was divided into 2 stages and operated for 48 days. In Stage I, the MBR was continuously operated for 24 days without the application of electrodes. In Stage II, the SMEBR+ was continuously operated for 24 days, while aluminum electrodes and an intermittent DC were working with an operational mode of 2 min ON/4 min OFF at a constant voltage of 1.4 V. The results indicated that membrane fouling was reduced by nearly 22.02% in the SMEBR+ compared to the MBR. The results also showed that the SMEBR+ increased the quality of effluent to the extent that high removals of NH3+-N, PO43−-P, and chemical oxygen demand (COD) were 98%, 76%, and 90%, respectively. This system, in comparison with those proposed in other studies, showed a suitable improvement in biological treatments, considering the high removal of NH3+-N. Therefore, SMEBR+ can be considered as a promising treatment alternative to the conventional MBR.

Novel Anammox Membrane Electro-Bioreactor

Abstract This paper presents an alternative method for nitrogen removal using modified membrane reactor. A novel Anammox submerged membrane electro-bioreactor (Anammox-SMEBR) was developed to enhance nitrogen removal from municipal wastewater. At lab scale a comparison between continuous flow MBE and Anammox-SMEBR reactors was conducted. The novel reactor removed nitrate and ammonia by over 95% and 97%, respectively. The removal was due to subsequent application of aerobic and anoxic conditions in the same reactor. On other hand, MBR was able to remove ammonia by 60 to 76%, while nitrates were produced. Simultaneously, COD and phosphorous removals in MBR were also lower than in Anammox-SMEBR.

Electro-conditioning of activated sludge in a membrane electro-bioreactor for improved dewatering and reduced membrane fouling

The impact of applying a direct current (DC) field on the morphology and structural composition of municipal wastewater flocs and their bound water content was investigated. The effects on sludge dewaterability and membrane fouling were assessed using batch electro-bioreactors and continuous flow submerged membrane electro-bioreactor (SMEBR). Series of batch electro-bioreactors were tested at current densities (CD) ranging between 5 and 35A/m2 for three concentrations of mixed liquor suspended solids (from 3000 to 15,000mg/l) and five electrical exposure modes (time-ON/time-OFF). Results of batch tests showed that CD of 15 to 35A/m2 enhanced sludge filterability, represented as specific resistance to filtration (SRF), up to 200 times compared to sludge in the control reactor. Electrically enhanced sludge under continuous flow (SMEBR) exhibited a reduction of SRF over the conventional activated sludge from 8 to 86 times, while membrane fouling rate decreased by 6 times. It was assumed that the removal of organic materials and soluble microbial products (SMP) through electro-coagulation (up to 90% for polysaccharides and up to 50% for protein), reduction of bound water by electroosmosis, increasing floc size through electro-bio-flocculation and the reduction of sludge organic/inorganic ratio were the major mechanisms contributed to SRF and membrane fouling reduction.

Optimized coupling of an intermittent DC electric field with a membrane bioreactor for enhanced effluent quality and hindered membrane fouling

This article studies a submerged membrane electro-bioreactor (SMEBR), an integrated system embracing biological treatment, electrical coagulation, and membrane filtration, all in one individual reactor, by applying an alternating electric field to a membrane bioreactor (MBR). The alternating electric field has been applied with current densities ranging from 5 to 23A/m2 under eight different electrical exposure modes. The results indicate that under the optimum condition with a current density of 12.5A/m2 and an exposure mode of (415s OFF–185s ON), the COD and phosphate removals would be respectively 4% and 43% more compared to an unmodified MBR system. Also at the same current density but with an exposure mode of (496s OFF–104s ON), ammonia removal efficiency was 22% more than the MBR system. At lower current density of 5 with an exposure mode (400s OFF–200s ON), the amounts of polysaccharides and proteins were respectively 59% and 51% less than ordinary membrane bioreactor. In summary, the SMEBR reactor membrane fouling is hindered while filtration course and particle size increase. Moreover, at current density less than 20A/m2 sludge activity enhances.

Start-up period investigation of pilot-scale submerged membrane electro-bioreactor (SMEBR) treating raw municipal wastewater

Submerged membrane electro-bioreactor (SMEBR) is a new hybrid technology for wastewater treatment employing electrical field and microfiltration in a nutrient-removing activated sludge process. A pilot SMEBR system was located at the wastewater treatment plant in the City of l’Assomption (Quebec, Canada) with the objective of investigating the start-up period performance under variable organic loadings and environmental conditions with respect to effluent quality, membrane fouling, and sludge properties. The pilot SMEBR facility was fed with the raw de-gritted municipal wastewater. At steady state operation, the removal efficiencies of ammonia (as NH3+-N), phosphorus (as PO43--P), and COD were 99%, 99%, and 92%, respectively. No substantial increase in the monitored transmembrane pressure as 0.02kPad−1 was reported. The time necessary to filter 100mL of the sludge sample has decreased by 78% after treatment whilst the sludge volume index averaged 119mLg−1. Energy requirements were in the range of 1.1–1.6kWhm−3 of wastewater. It was concluded that the SMEBR is a very competitive technology when compared to conventional membrane systems as it can enhance treatment performance to an appreciable extent, remove phosphorus and reduce fouling.

Novel electrokinetic approach reduces membrane fouling

An innovative submerged membrane electro-bioreactor (SMEBR) was built to reduce membrane fouling through a combination of various electrokinetic processes. The objective of this research was to assess the capability of SMEBR to reduce fouling under different process conditions. At the bench scale level, using synthetic wastewater, membrane fouling of the SMEBR was compared to the fouling of a membrane bioreactor (MBR) in five runs. Different protein concentrations in the influent synthetic wastewater were selected to develop different membrane fouling potentials: high (240 mg/l), low (80 mg/l) and zero protein addition. The MBR and SMEBR were operated at a flux equal to the membrane critical flux in order to create high fouling rate conditions. Membrane fouling rate, expressed as the change in the trans-membrane pressure per day (kPa/d), decreased in the SMEBR 5.8 times (standard deviation (SD) = 2.4) for high protein wastewater, 5.1 times (SD = 2.4) for low protein content, and 1.3 times (SD = 0.7) for zero protein, when compared to the MBR. The supernatant concentrations of the soluble microbial products (SMP) were 195–210, 65–135 and less than 65 mg/l in respective experimental series. Following the bench scale study, membrane fouling was assessed in a pilot scale SMEBR, fed with raw un-clarified municipal wastewater, and operated under real-sewage variable quality conditions. The pilot SMEBR exhibited three times smaller membrane fouling rate than the MBR. It was concluded that electrokinetic processes generated by SMEBR led to a reduction of membrane fouling through: i) removal of soluble microbial products (mainly protein and polysaccharides) and colloidal organic materials; ii) change of the structure and morphology of the suspended solids due their conditioning by DC field.

Modification of activated sludge properties caused by application of continuous and intermittent current

This study investigated the impact of direct current (DC) field on the activated sludge properties for potential improvement of the biological as well as membrane treatment processes. Three mixed-liquor suspended solids (MLSS) concentrations (5,000, 10,000 and 15,000 mg/l) were subjected to current densities (CD) ranging from 5 to 50 A/m2 at five electrical exposure modes (time-ON/time-OFF). The results showed that CD between 15 and 35 A/m2 increased the filterability of the sludge more than 200 times when compared with the untreated reference sludge. The average removals of protein, polysaccharides and organic colloids from the sludge supernatant at this range of CD were 43%, 73% and 91%, respectively, while the average reduction of the specific resistance to filtration (SRF) was 4.8 times higher. The changes of sludge properties depended on the current density, electrical exposure mode and the MLSS concentration. At CD of 25 A/m2 and MLSS below 10,000 mg/l, shorter time-OFF was needed in each electrical cycle, while more time-OFF was needed at higher MLSS concentrations. It was concluded that proper application of the DC field could improve biomass in terms of its dewaterability and the removal of SMP, which are highly correlated to membrane fouling in the submerged membrane electro-bioreactor (SMEBR).

Correlations between trans-membrane pressure (TMP) and sludge properties in submerged membrane electro-bioreactor (SMEBR) and conventional membrane bioreactor (MBR)

The influence of sludge properties in SMEBR and conventional MBR pilot systems on membrane fouling was investigated. Generated data were analyzed using statistical analysis Pearson’s product momentum correlation coefficient (rp). Analysis showed that TMP had strong direct (rp=0.9182) and inverse (rp=−0.9205) correlations to mean particle size diameter in MBR and SMEBR, respectively. TMP in SMEBR had a strong direct correlation to the sludge mixed liquor suspended solids concentration (MLSS) (rp=0.7757) while a weak direct correlation (rp=0.1940) was observed in MBR. SMEBR showed a moderate inverse correlation (rp=−0.6118) between TMP and soluble carbohydrates (EPSc) and a very weak direct correlation (rp=0.3448) to soluble proteins (EPSp). Conversely, EPSp in MBR had more significant impact (rp=0.4856) on membrane fouling than EPSc (rp=0.3051). The results provide insight into optimization of operational conditions in SMEBR system to overcome membrane fouling.

Performance of the submerged membrane electro-bioreactor (SMEBR) with iron electrodes for wastewater treatment and fouling reduction

This paper presents the results of the performance of a novel technology called submerged membrane electro-bioreactor (SMEBR). The SMEBR treats wastewater by combining membrane filtration, electrokinetic phenomena, and biological processes in one reactor, and improves treatment performance while helping to control membrane fouling. The newly designed SMEBR system was based on applying an intermittent direct current (DC) field between immersed circular perforated electrodes around a membrane filtration module. The SMEBR system significantly reduced the fouling rate when iron worked as electrodes and an intermittent DC with an operational mode of 15 min ON–45 min OFF was applied. In terms of effluent quality, the SMEBR system enhanced the removal of COD and PO 4-P up to 96% and 98%, respectively.

Pilot Studies of a Novel Submerged Membrane Electro-Bioreactor (SMEBR)

Pilot Studies of a Novel Submerged Membrane Electro-Bioreactor (SMEBR)

Development of a Novel Submerged Membrane Electro-Bioreactor (SMEBR): Performance for Fouling Reduction

A novel Submerged Membrane Electro-Bioreactor (SMEBR) was developed to treat wastewater and control the problem of membrane fouling. To validate the new design, experimental work was achieved in a few phases. This paper describes the design constraints and criteria of the new developed SMEBR system, and shows the results of the performance of the SMEBR system to reduce membrane fouling when intermittent direct current (DC) (15 min ON/45 min OFF) was applied using cylindrical iron mesh for both electrodes. Application of the SMEBR system enhanced the membrane filterability by reducing the fouling rate up to 16.3% without any backwashing of the membrane module. The improvement in membrane filterability associated with a decrease in zeta potential of the mixed liquor flocs from -30.5 up to -15.3 mV and a decrease in specific resistance to filtration (SRF) up to 40% was observed.

Submerged Membrane Electro-Bioreactor (SMEBR) Reduces Membrane Fouling and Achieves Phosphorus Removal

Submerged Membrane Electro-Bioreactor (SMEBR) Reduces Membrane Fouling and Achieves Phosphorus Removal