New Perspectives on Membrane Bioreactors

A special issue of Membranes (ISSN 2077-0375). This special issue belongs to the section "Membrane Chemistry".

Deadline for manuscript submissions: closed (31 August 2020) | Viewed by 21160

Special Issue Editors


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Guest Editor
School of Geotechnical Sciences, Department of Food Science and Technology, International Hellenic University, Sindos, GR-57400, Thessaloniki, Greece
Interests: municipal and industrial wastewater treatment; membrane bioreactors; water treatment; anaerobic digestion; membrane fouling control; activated carbon; sludge stabilization
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E-Mail Website
Guest Editor
Department of Chemical Engineering, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece
Interests: wastewater treatment; membrane bioreactors; activated sludge processes; water quality and treatment; analytical chemistry; removal of toxic parameters from water; chemical engineering
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Laboratory of Technologies of Environmental Protection and Utilization of Food By-Products, Department of Food Science and Technology, International Hellenic University, GR-57400 Thessaloniki, Greece
Interests: wastewater treatment; membrane bioreactors; membrane fouling mitigation; membrane processes; activated sludge process; soluble microbial products; extracellular polymeric substances
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Membrane bioreactor (MBR) technology is based on the combination of an activated sludge process and membrane filtration, resulting in a high-quality effluent. It is an advanced wastewater treatment process that has been developed over several decades, while the application of this technology has seen a constantly increasing annual growth rate. It is a promising process for the treatment of a large variety of wastewater, mostly due to its significant benefits over the conventional activated sludge process.

However, despite the many advantages of MBRs, membrane fouling remains the main obstacle preventing their universal application. Membrane fouling is attributed to the deposition of substances released by sludge microflora onto the surface and inside of the membrane pores, resulting in a loss of permeability and ultimately increasing the operational costs.

MBRs are classified into two groups: aerobic and anaerobic. Moreover, dynamic membrane (DM) filtration, which involves the formation and effective use of a cake layer on a support layer instead of a membrane, presents a new and innovative concept. To date, various novel membranes have been developed, such as composite hydrophobic–hydrophilic membranes, composite supported liquid membranes, asymmetric membranes with finger-like macrovoids, and one-step-fabricated asymmetric membranes.

Additionally, in recent decades, numerous attempts have been made to design and fabricate effective membrane modules with optimized geometries and/or shear-induced accessories to enhance permeation flow and suppress undesirable polarization and membrane fouling, through passive or active enhancement techniques.

The aim of this Special Issue is to present novel perspectives on MBRs and membrane technologies, and to show recent progress in membrane fouling mitigation. All aspects that contribute to the innovation of the design and application of MBRs are of interest. We appeal to share a scientific joy with all of you that wish to contribute to this Issue. The submission site is ready to receive your contributions to membrane bioreactors science.

Prof. Petros Samaras
Dr. Manassis Mitrakas
Dr. Dimitra Banti
Guest Editors

Manuscript Submission Information

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Keywords

  • Aerobic and anaerobic MBRs;
  • Membrane fouling and mitigation;
  • Microfiltration, ultrafiltration, nanofiltration;
  • Membranes for industrial wastewater treatment;
  • Dynamic membrane technology;
  • Novel membranes and fabrication methods;
  • Innovative membrane module design;
  • Modeling of membrane processes;
  • Life-cycle analysis and environmental optimization of MBRs;
  • Novel configurations in MBR processes

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Published Papers (5 papers)

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Research

11 pages, 1929 KiB  
Article
Performance of a Micro-Scale Membrane Reactor for Greywater Treatment at Household Level
by Vasileios Diamantis
Membranes 2021, 11(1), 63; https://doi.org/10.3390/membranes11010063 - 17 Jan 2021
Cited by 4 | Viewed by 4248
Abstract
An aerated membrane reactor (25 L working volume) equipped with 1.5 m2 hollow-fiber module was designed and operated using synthetic greywater for household water reuse. Activated sludge (MBR), activated carbon (PAC), zeolite (ZEO) and iron hydroxide (GEH) were added in separate experiments [...] Read more.
An aerated membrane reactor (25 L working volume) equipped with 1.5 m2 hollow-fiber module was designed and operated using synthetic greywater for household water reuse. Activated sludge (MBR), activated carbon (PAC), zeolite (ZEO) and iron hydroxide (GEH) were added in separate experiments to optimize membrane hydraulic performance and removal efficiency of organics. The use of additives improved permeate quality (in terms of Chemical Oxygen Demand—COD) compared to the direct membrane filtration mode of operation. GEH and MBR were efficient for phosphorus removal, which was not the case for PAC and ZEO. No significant improvement of membrane flux was recorded when PAC, ZEO or GEH were added inside the membrane tank. The MBR system displayed optimum performance during medium-term operation, with COD removal efficiency 85% and permeate flux between 40 and 25 L m−2 h−1. The capital costs of the proposed technology were around 300 € and the operational costs below 80 € yr−1, rendering the process feasible at household level. Greywater treatment systems for household applications are still on their infancy; however, this trend is expected to change due public perception towards circular economy, water conservation and reuse. Full article
(This article belongs to the Special Issue New Perspectives on Membrane Bioreactors)
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15 pages, 1852 KiB  
Article
LCA of a Membrane Bioreactor Compared to Activated Sludge System for Municipal Wastewater Treatment
by Dimitra C. Banti, Michail Tsangas, Petros Samaras and Antonis Zorpas
Membranes 2020, 10(12), 421; https://doi.org/10.3390/membranes10120421 - 14 Dec 2020
Cited by 48 | Viewed by 5808
Abstract
Membrane bioreactor (MBR) systems are connected to several advantages compared to the conventional activated sludge (CAS) units. This work aims to the examination of the life cycle environmental impact of an MBR against a CAS unit when treating municipal wastewater with similar influent [...] Read more.
Membrane bioreactor (MBR) systems are connected to several advantages compared to the conventional activated sludge (CAS) units. This work aims to the examination of the life cycle environmental impact of an MBR against a CAS unit when treating municipal wastewater with similar influent loading (BOD = 400 mg/L) and giving similar high-quality effluent (BOD < 5 mg/L). The MBR unit contained a denitrification, an aeration and a membrane tank, whereas the CAS unit included an equalization, a denitrification, a nitrification, a sedimentation, a mixing, a flocculation tank and a drum filter. Several impact categories factors were calculated by implementing the Life Cycle Assessment (LCA) methodology, including acidification potential, eutrophication potential, global warming potential (GWP), ozone depletion potential and photochemical ozone creation potential of the plants throughout their life cycle. Real data from two wastewater treatment plants were used. The research focused on two parameters which constitute the main differences between the two treatment plants: The excess sludge removal life cycle contribution—where GWPMBR = 0.50 kg CO2-eq*FU−1 and GWPCAS = 2.67 kg CO2-eq*FU−1 without sludge removal—and the wastewater treatment plant life cycle contribution—where GWPMBR = 0.002 kg CO2-eq*FU−1 and GWPCAS = 0.14 kg CO2-eq*FU−1 without land area contribution. Finally, in all the examined cases the environmental superiority of the MBR process was found. Full article
(This article belongs to the Special Issue New Perspectives on Membrane Bioreactors)
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12 pages, 2021 KiB  
Article
Removal of Bacteria and Organic Carbon by an Integrated Ultrafiltration—Nanofiltration Desalination Pilot Plant
by Zahid Ur Rehman, Bayan Khojah, TorOve Leiknes, Safiya Alsogair and Mona Alsomali
Membranes 2020, 10(9), 223; https://doi.org/10.3390/membranes10090223 - 4 Sep 2020
Cited by 9 | Viewed by 3837
Abstract
Fouling caused by organic matter and bacteria remains a significant challenge for the membrane-based desalination industry. Fouling decreases the permeate quality and membrane performance and also increases energy demands. Here, we quantified the amount of organic matter and bacteria at several stages along [...] Read more.
Fouling caused by organic matter and bacteria remains a significant challenge for the membrane-based desalination industry. Fouling decreases the permeate quality and membrane performance and also increases energy demands. Here, we quantified the amount of organic matter and bacteria at several stages along the water-treatment train of an integrated ultrafiltration–nanofiltration seawater treatment pilot plant. We quantified the organic matter, in terms of Total Organic Carbon (TOC) and Assimilable Organic Carbon (AOC), and evaluated its composition using Liquid Chromatography for Organic Carbon Detection (LC-OCD). The bacterial cells were counted using Bactiquant. We found that ultrafiltration (UF) was effective at removing bacterial cells (99.7%) but not TOC. By contrast, nanofiltration (NF) successfully removed both TOC (95%) and bacterial cells. However, the NF permeate showed higher amounts of AOC than seawater. LC-OCD analysis suggested that the AOC was mostly composed of low molecular weight neutral substances. Furthermore, we found that the cleaning of the UF membrane using chemically enhanced backwash reduced the amount of AOC released into the UF permeate. By implementing the cleaning-in-place of the NF membrane, the pressure drop was restored to the normal level. Our results show that the UF and NF membrane cleaning regimes investigated in this study improved membrane performance. However, AOC remained the hardest-to-treat fraction of organic carbon. AOC should, therefore, be monitored closely and regularly to mitigate biofouling in downstream processes. Full article
(This article belongs to the Special Issue New Perspectives on Membrane Bioreactors)
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15 pages, 5334 KiB  
Article
Combined Effect of Colloids and SMP on Membrane Fouling in MBRs
by Dimitra Banti, Manassis Mitrakas, Georgios Fytianos, Alexandra Tsali and Petros Samaras
Membranes 2020, 10(6), 118; https://doi.org/10.3390/membranes10060118 - 6 Jun 2020
Cited by 23 | Viewed by 3302
Abstract
Membrane fouling investigations in membrane bioreactors (MBRs) are a top research issue. The aim of this work is to study the combined effect of colloids and soluble microbial products (SMPs) on membrane fouling. Two lab-pilot MBRs were investigated for treating two types of [...] Read more.
Membrane fouling investigations in membrane bioreactors (MBRs) are a top research issue. The aim of this work is to study the combined effect of colloids and soluble microbial products (SMPs) on membrane fouling. Two lab-pilot MBRs were investigated for treating two types of wastewater (wwt), synthetic and domestic. Transmembrane pressure (TMP), SMP, particle size distribution and treatment efficiency were evaluated. Chemical Oxygen Demand (COD) removal and nitrification were successful for both kinds of sewage reaching up to 95–97% and 100%, respectively. Domestic wwt presented 5.5 times more SMP proteins and 11 times more SMP carbohydrates compared to the synthetic one. In contrast, synthetic wwt had around 20% more colloids in the mixed liquor with a size lower than membrane pore size (<400 nm) than domestic. Finally, the TMP at 36 days reached 16 kPa for synthetic wwt and 11 kPa for domestic. Therefore, synthetic wwt, despite its low concentration of SMPs, caused severe membrane fouling compared to domestic, a result that is attributed to the increased concentration of colloids. Consequently, the quantity of colloids and possibly their special characteristics play decisive and more important roles in membrane fouling compared to the SMP—a novel conclusion that can be used to mitigate membranes fouling. Full article
(This article belongs to the Special Issue New Perspectives on Membrane Bioreactors)
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19 pages, 3392 KiB  
Article
Using Additives for Fouling Control in a Lab-Scale MBR; Comparing the Anti-Fouling Potential of Coagulants, PAC and Bio-Film Carriers
by Petros Gkotsis, Anastasios Zouboulis and Manassis Mitrakas
Membranes 2020, 10(3), 42; https://doi.org/10.3390/membranes10030042 - 12 Mar 2020
Cited by 11 | Viewed by 3168
Abstract
This study investigates the effect of different additives, such as coagulants/flocculants, adsorption agents (powdered activated carbon, PAC), and bio-film carriers, on the fouling propensity of a lab-scale membrane bio-reactor (MBR) treating synthetic municipal wastewater. The coagulation agents FO 4350 SSH, Adifloc KD 451, [...] Read more.
This study investigates the effect of different additives, such as coagulants/flocculants, adsorption agents (powdered activated carbon, PAC), and bio-film carriers, on the fouling propensity of a lab-scale membrane bio-reactor (MBR) treating synthetic municipal wastewater. The coagulation agents FO 4350 SSH, Adifloc KD 451, and PAC1 A9-M at concentrations of 10 mg/L, 10 mg/L, and 100 mg Al/L, respectively, and PAC at a concentration of 3.6 ± 0.1 g/L, exhibited the best results during their batch-mode addition to biomass samples. The optimal additives FO 4350 SSH and Adifloc KD 451 were continuously added to the bioreactor at continuous-flow addition experiments and resulted in increased membrane lifetime by 16% and 13%, respectively, suggesting that the decrease of SMPc concentration and the increase of sludge filterability is the dominant fouling reduction mechanism. On the contrary, fouling reduction was low when PAC1 A9-M and PAC were continuously added, as the membrane lifetime was increased by approximately 6%. Interestingly, the addition of bio-film carriers (at filling ratios of 40%, 50%, and 60%) did not affect SMPc concentration, sludge filterability, and trans-membrane pressure (TMP). Finally, the effluent quality was satisfactory in terms of organics and ammonia removal, as chemical oxygen demand (COD), biochemical oxygen demand (BOD)5, and NH 4 + -N concentrations were consistently below the permissible discharge limits and rarely exceeded 30, 15, and 0.9 mg/L, respectively. Full article
(This article belongs to the Special Issue New Perspectives on Membrane Bioreactors)
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