Unraveling microbial community by next-generation sequencing in living membrane bioreactors for wastewater treatment.

This study delves into the microbial community complexity and its role in self-forming dynamic membrane (SFDM) systems, designed to remove nutrients and pollutants from wastewater, by means of the analysis of Next-Generation Sequencing (NGS) data. In these systems, microorganisms are naturally incorporated into the SFDM layer, which acts as a biological and physical filter. The microorganisms present in an innovative and highly efficient aerobic, electrochemically enhanced, encapsulated SFDM bioreactor were studied to elucidate the nature of the dominant microbial communities present in sludge and in encapsulated SFDM, patented as living membrane® (LM) of the experimental setup. The results were compared to those obtained from the microbial communities found in similar experimental reactors without an applied electric field. The data gathered from the NGS microbiome profiling showed that the microbial consortia found in the experimental systems are comprised of archaeal, bacterial, and fungal communities. However, the distribution of the microbial communities found in e-LMBR and LMBR had significant differences. The results showed that the presence of an intermittently applied electric field in e-LMBR promotes the growth of some types of microorganisms (mainly electroactive microorganisms) responsible for the highly efficient treatment of the wastewater and for the mitigation of the membrane fouling found for those bioreactors.

Innovative encapsulated self-forming dynamic bio-membrane bioreactor (ESFDMBR) for efficient wastewater treatment and fouling control.

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.

Wastewater treatment and fouling control in an electro algae-activated sludge membrane bioreactor.

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.