Self-forming Dynamic Membrane Research Articles

Electro living membrane bioreactor for highly efficient wastewater treatment and fouling mitigation: Influence of current density on process performances

The next generation of the self-forming dynamic membrane, referred to in this study as the “Living Membrane (LM)”, is a new patented technology based on an encapsulated biological layer that self-forms on a designed coarse-pore size support material during wastewater treatment and acts as a natural membrane filter. Integrating electrochemical processes with wastewater treatment using the LM approach has also been recently studied (the reactor is referred to as the Electro-Living Membrane Bioreactor or e-LMBR). This study investigated the effects of varying current densities, i.e., 0.3, 0.5, and 0.9 mA/cm2, on the performance of an e-LMBR. The results were also compared with those of the Living Membrane Bioreactor or LMBR (without applied current density).Higher pollutant removals were observed in the presence of the electric field. However, the effect of varying applied current densities on the COD (98–99 %), NH3-N (97–99 %), and PO43−P (100 %) removals was not statistically significant. The more prominent differences (p < 0.05) were observed in the decrease of NO3−-N concentrations from mixed liquor to effluent, with increasing current density resulting in lower mean NO3−-N effluent concentrations (0.3 mA/cm2: 6.13 mg/L; 0.5 mA/cm2: 4.38 mg/L; 0.9 mA/cm2: 3.70 mg/L). The reduction of NO3−-N concentrations as wastewater permeated through the LM layer also confirmed its role in removing nitrogen-containing compounds.Higher current densities resulted in lower concentrations of fouling substances, particularly those of microbial extracellular polymeric substances (EPS) and transparent exopolymer particles (TEPs). The average values of the temporal variation of transmembrane pressure (d(TMP)/d(t)) in the e-LMBR were extremely low, in the range of 0.013–0.041 kPa/day, throughout the operation period. The highest (d(TMP)/d(t)) was observed for the highest current density. However, the TMP values remained below 2 kPa in all the e-LMBR runs even after the initial LM formation stage.

Optimal Mesh Pore Size Combined with Periodic Air Mass Load (AML) for Effective Operation of a Self-Forming Dynamic Membrane BioReactor (SFD MBR) for Sustainable Treatment of Municipal Wastewater

A self-forming dynamic membrane bioreactor (SFD MBR) is a cost-effective alternative to conventional MBR, in which the synthetic membrane is replaced by a “cake layer,” an accumulation of the biological suspension over a surface of inert, low-cost support originated by filtration itself. Under optimized conditions, the cake layer is easy to remove and quick to form again, resulting a “dynamic membrane.” The permeate of the SFD MBR has chemo-physical characteristics comparable to those of conventional ultrafiltration-based MBR. In this paper, two nylon meshes with pore sizes of 20 and 50 µm, respectively, were tested in a bench-scale SFD MBR in which an air mass load (AML) was periodically supplied tangentially to the filtration surface to maintain filtration effectiveness. The SFD MBR equipped with 20 µm nylon mesh coupled with 5 min of AML every 4 h showed the best performance, ensuring both a permeate with turbidity values always below 3 NTU and revealing no increases in transmembrane pressure (TMP) with manual maintenance needs. A benchmark test with the only difference of a suction break (relaxation) instead of AML was conducted under identical operating conditions for validation with an already known maintenance strategy. This latter test produced a permeate of very good quality, but it needed frequent TMP increases and consequent manual cleanings, showing that a periodic AML coupled with the use of a 20 µm mesh can be an optimal strategy for long-term operation of SFD MBR.

Optimization of Critical Factors Affecting Dynamic Membrane Formation in a Gravity-Driven Self-Forming Dynamic Membrane Bioreactor towards Low-Cost and Low-Maintenance Wastewater Treatment

Self-forming dynamic membrane (SFDM) formation is affected by a variety of operating conditions. However, previous studies have only focused on individual influencing factors and a systematic analysis of important factors is lacking. In this study, an aerobic self-forming dynamic membrane bioreactor (SFDMBR) was developed for the treatment of domestic wastewater with the critical factors that affect the effective formation of SFDM optimized, and the operational performances under optimized formation conditions confirmed. The results indicated that SFDM could be formed within 5 min using 48 μm stainless-steel mesh as the supporting material at a sludge concentration of 5–6 g/L and a gravity waterhead of 15 cm. And the SFDM formed could maintain a stable flux of 30–50 LMH, and the removals of COD, SCOD, and NH4+-N were 93.28%, 82.85%, and 95.46%, respectively. Furthermore, the cake layer resistance (reversible fouling) contributed to 95.93% of the total filtration resistance, thus a simple physical cleaning can effectively restore the flux indicating a low-maintenance requirement. This study provides valuable insights into the optimization and application of the SFDMBR process.

Comparison of fine bubble scouring, backwash, and mass air load supply for dynamic membrane maintenance and steady operation in SFD MBR for wastewater treatment

The self-forming dynamic membrane bioreactor (SFD MBR) is an evolution of the conventional ultrafiltration-based MBR where filtration occurs through a cake layer (dynamic membrane, DM) supported by a filtration net. The effluent quality levels that may be achieved through this technology are comparable to those of conventional MBR and suitable for effluent reuse, as shown in previous research. In addition, SFD MBR are more sustainable, both in terms of investment costs (filtration net materials are cheaper than UF membranes), and operation. Indeed, the typical operating pressure of these systems is below 100 mbar, thus compatible with gravity-driven operation. Nevertheless, as all membrane-based processes, also SFD MBR require periodic maintenance cleaning of the supports holding the filtering layers, in order to ensure high and constant effluent quality and steady operation. In this paper, different strategies for continuous or temporized cyclic DM maintenance aimed at limiting the frequency of on-site manual cleaning interventions are compared. In particular, five tests were performed at the bench scale adopting the same process conditions except for the type of DM maintenance strategy. Continuous fine-bubble air scouring of the membrane surface was compared with two intermittent cyclic procedures based on backwash with permeate (with and without simultaneous air scouring) and mass air load supply (with two cycles of different durations), respectively. The results have confirmed the overall high performance of this technology under all the tested conditions, with COD removal efficiencies always exceeding 86 %, effluent turbidity values normally well below 5 NTU (and often much lower), complete nitrification and partial nitrogen removal. Furthermore, the comparison among the different DM maintenance strategies has shown that the mass air load supply is the most efficient approach towards sustainable operation. In particular, shorter mass air load cycles provided the best performance in limiting the manual cleaning needs, which under this condition were as low as once every 3 weeks. The key finding of this study is the demonstration of cyclic air mass load as an effective preventive cleaning strategy allowing good performance of a bench-scale SFD MBR, strongly reducing the manual maintenance requirements. More experiments are required to confirm these results in larger scale installations.

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.

A novel precoated anaerobic dynamic membrane bioreactor for real domestic wastewater treatment: In-situ formation, filtration performance and characterization of dynamic membrane

Precoated dynamic membranes (PCDM), commonly formed by retaining external particles on coarse supporting meshes, can accelerate dynamic membrane (DM) formation, change the DM structure, and enhance its filtration performance. An in-situ rapid PCDM formation method via short-time and high-flux initial filtration (at 380 L/m2·h flux for 0.25 min) is proposed using anaerobic sludge as a precoating material. A precoated anaerobic dynamic membrane bioreactor (PC-AnDMBR) was operated in parallel with a self-forming AnDMBR (SF-AnDMBR) to treat domestic wastewater. Extremely low rates of transmembrane pressure (TMP) increase of 0.05 and 0.07 kPa/d were obtained during the long-term operation of the SF-AnDMBR and PC-AnDMBR, respectively. Furthermore, the PC-AnDMBR and SF-AnDMBR showed stable effluent turbidity (27.1 ± 9.44 NTU and 31.35 ± 15.96 NTU, respectively) and satisfactory COD removal (83% and 78%, respectively), which were attributed to the small pore size (<2 μm) of the DM layers. The PCDM and self-forming dynamic membrane (SFDM) with a thickness of 0.7 mm were further characterized as cake and gel layers, whereas the gel layer thickness within the PCDM was higher than that of the SFDM (0.6 mm vs. 0.2 mm). In addition, the porosities of the gel layers (2.87% and 2.95%) were lower than those of the cake layers (3.58% and 3.48%) for the PCDM and SFDM, respectively. Therefore, the compact gel layer, with more accumulated organics, contributed to over 78% of the total filtration resistance. These findings provide new insights into the mechanisms of PCDM formation and the application of AnDMBRs in wastewater treatment.

Enhanced membrane fouling control through Self Forming Dynamic Membrane and sponge-wrapped membrane: A Novel membrane bioreactor.

Membrane technology offers a wide variety of advantages in wastewater treatment, but fouling impedes its widespread applications. Hence, in this study, a novel method was tried to control membrane fouling by combining the self-forming dynamic membrane (SFDM) with a sponge-wrapped membrane bioreactor. The configuration is termed a "Novel-membrane bioreactor" (Novel-MBR). To compare the performance of Novel-MBR, a Conventional membrane bioreactor (CMBR) was operated under similar operating conditions. CMBR and Novel-MBR were run consequently for 60 days and 150 days, respectively. The Novel-MBR was comprised of self-forming dynamic membranes (SFDMs) in two compartments before a sponge-wrapped membrane in the membrane compartment. In Novel-MBR, the formation times for SFDMs on coarse (125μm) and fine (37μm) pore cloth filers were 43 minutes and 13 minutes, respectively. The CMBR experienced more frequent fouling; the maximum fouling rate was 5.83 kPa/d. In CMBR, the membrane fouling due to cake layer resistance (6.92×1012 m-1 ) was high, and that alone contributed to 84% of fouling. In Novel-MBR, the fouling rate was 0.0266 kPa/d and the cake layer resistance was 0.329×1012 m-1 . Also, the Novel-MBR experienced 21 times less reversible fouling and 36 times less irreversible fouling resistance than the CMBR. In Novel-MBR, the formed SFDM and the sponge wrapped on the membrane helped to reduce both reversible and irreversible fouling. With the modification tried in the present study, the Novel-MBR experienced less fouling, and the maximum transmembrane pressure at the end of 150 days of operation was 4 kPa.

Impacts and mechanism of total organic sulfur in extracellular polymeric substances on fouling of the anaerobic self-forming dynamic membrane bioreactor

A side-stream cross-flow anaerobic self-forming dynamic membrane bioreactor (AnSFDMBR) connected with an up-flow anaerobic sludge blanket (UASB) reactor was used to replace the UASB and middle settling tank in sulfate reduction, autotrophic denitrification, and nitrification integrated (SANI) process. To reduce the water and energy consumption for AnSFDMBR backwashing, the optimum condition of trans-membrane pressure (TMP)-based backwashing were investigated under sequential batch operations. Based on the optimum condition, a lab-scale AnSFDMBR was operated continuously for 243 days without a drop in flux, with good effluent quality. In the sequential batch operation study, AnSFDMBR showed no significant accumulation of total extracellular polymeric substances (EPSs) during 40 days of operation without backwashing. Polysaccharides slightly accumulated in the dynamic layer regardless of the final TMP and operation duration, indicating that TMP-based backwashing is suitable for the studied AnSFDMBR system. In long-term operation with TMP-based backwashing, total EPSs in dynamic layer to sludge ratio dramatically dropped during the fouling phase. According to the evaluation of total organic sulfur (TOS) in dynamic layer and mesh EPSs, it was found that TOS, mainly poly-sulfur generated in UASB reactor, played a critical role in fouling in saline wastewater treatment. TOS deposited on the mesh over 40% by weight of the total EPS in the fouling phase clearly led to system fouling. Additional sequential batch operations with different seawater percentages (%V/V) (control, 10%, 20%, 30% and 50%) demonstrated that the TOS accumulation on the mesh increased with time and salinity which also aligned with the long-term operation.

Living membrane bioreactor for highly effective and eco-friendly treatment of textile wastewater

The treatability of synthetic textile wastewater containing model dyes, such as reactive black and direct black dye (25.0 ± 2.6 mgdye/L), with chemical oxygen demand (COD, 1000 ± 113 mg/L), ammonia‑nitrogen (NH3-N, 140 ± 97 mg/L) and sulphate ions (SO₄2−, 1357 ± 10.86 mg/L) was investigated in this study using an innovative living membrane bioreactor (LMBR) using an encapsulated self-forming dynamic membrane (ESFDM). The key advantage of ESFDMBR is the self-forming of the biological filtering layer protected between two meshes of inert robust and inexpensive material. A laboratory scale bioreactor (BR) equipped with a filtering unit mounting polyester meshes with a pore size of 30 μm, operated at an influent flux of 30 LMH was thus used. After the formation of the biological living membrane (LM), the treatment significantly reduced COD and DOC concentrations to the average values of 34 ± 10 mg/L and 32 ± 7 mg/L, corresponding to reduction efficiencies of 96.0 ± 1.1 % and 94 ± 1.05 %, respectively. Throughout the LMBR operation, the colours were successfully removed from synthetic textile wastewater with an overall removal efficiency of about 85.0 ± 1.8 and 86.0 ± 1.9 % for direct and reactive dyes, respectively. In addition, the proposed system was also found effective in affording removal efficiency of ammonia (NH3) of 97 ± 0.5 %. Finally, this treatment afforded circa 40.7 ± 5.8 % sulphate removal, with a final concentration value of 805 ± 78.61 mg/L. The innovative living membrane, based on an encapsulated self-forming dynamic membrane allows a prolonged containment of the membrane fouling, confirmed by investigating the concentration of membrane fouling precursors and the time-course variations of turbidity and transmembrane pressure (TMP). Those final concentrations of wastewater pollutants were found to be below the limits for admission of the effluents in public sanitation networks in Italy and Tunisia, as representative countries for the regulation in force in Europe and North Africa. In conclusion, due to the low costs of plant and maintenance, the simple applicability, the rapid online implementation, the application of LMBR results in a promising method for the treatment of textile wastewater.

Comparison of the formation, filtration performance, and structural characteristic of self-forming dynamic membranes under constant transmembrane pressure and constant filtration flux

The formation and filtration of self-forming dynamic membranes (SFDMs) can be affected by multiple factors, such as the operating conditions and sludge properties in membrane bioreactors. There has been limited research on the effects of the constant transmembrane pressure and constant filtration flux on the stable filtration of dynamic membranes. In the present study, a large-pore stainless steel mesh (70 µm pore size) was used as the support material for dynamic membrane formation to explore the formation, filtration performance, and structural characteristics of two dynamic membranes, P-SFDM (filtration under constant transmembrane pressure) and J-SFDM (filtration under constant flux), with the same initial filtration flux. The results showed that the stable filtration period of J-SFDM went up to 22.5 h, which was significantly longer than that of P-SFDM (5.5 h) with a higher resistance growth speed. The blocking process of the P-SFDM membrane conformed to the complete blocking model, whereas that of the J-SFDM membrane conformed to the standard blocking model in the initial stage and follows the intermediate blocking model in the later stage. Besides, the P-SFDM cake layer had a higher extracellular polymer content and smaller particle size (106 ± 2 mg·g−1 VSS, 546 ± 63 µm) than that of the J-SFDM cake layer (89 ± 3 mg·g−1 VSS, 615 ± 51 µm). During a 39-day continuous long-term operation, the energy consumptions per ton of water for J-SFDM and P-SFDM were 0.14 kw·h·t−1 and 0.19 kw·h·t−1, respectively. The above results show that the J-SFDM has a longer stable filtration period with lower energy consumption per ton of water.

Performance evaluation of membrane bioreactor coupled with self-forming dynamic membrane

In the present study, Conventional Membrane Bioreactor (C-MBR) and Modified Membrane Bioreactor (M-MBR) were run consequently to compare the fouling reduction through incorporated modification. M-MBR was developed by introducing a Self-forming dynamic membrane (SFDM) formed on a nylon cloth filter ahead of a flat sheet membrane. The coarse cloth filter and fine cloth filter had a pore size of 125 μm and 37 μm, respectively and it took 45 min and 12 min to form a dynamic membrane on them. The C-MBR experienced frequent fouling with cake layer resistance (RC) as the dominant one which contributed to 83.98% of total resistance (RT). Whereas in M-MBR the cake layer resistance (67.86% of RT) and pore blocking resistance (RP) (1.31% of RT) was less compared to C-MBR. The formed SFDM on nylon cloth filters led to the reduced RC and RP in M-MBR. Therefore, the operation of M-MBR was prolonged, which took 150 days to reach 8.6 KPa (0.057 KPa/day). Eventually, it was concluded that the modification made in this study significantly reduced the fouling.

Advanced wastewater treatment and membrane fouling control by electro-encapsulated self-forming dynamic membrane bioreactor

An advanced concept of aerobic membrane bioreactors (MBRs) for highly efficient wastewater treatment has been disclosed by introduction of an electro and encapsulated self-forming dynamic biomembrane (e-ESFDM). The biological filtering membrane is intercalated between two woven polyester fabrics as supports that assist the formation and protect the biomembrane. The innovative architecture of the e-ESFDM in combination with electrocoagulation processes resulted in efficient and cost-effective wastewater treatment and control of the membrane fouling. The performance of the e-ESFDMBR was compared to a yet highly efficient ESFDMBR, where the electric field was not present. The ESFDM-based reactors both showed comparable results in the removal of organic matter, in terms of COD and DOC. On the other hand, e-ESFDMBR exceeded the performance of the ESFDMBR in the reduction of nitrogen- and phosphorous-containing pollutants, responsible for eutrophication processes in the environment, and recalcitrant molecules, such as humic-like substances. In addition, an extremely low fouling rate was observed for the e-ESFDM bioreactor. Insights on the biological processes involved in the developed MBR were provided by investigations on the microbiological diversity found in reactor mixed liquor, ESFDM layer and treated wastewater.

Hybrid powdered activated carbon-activated sludge biofilm formation to mitigate biofouling in dynamic membrane bioreactor for wastewater treatment

Membrane costs and biofouling limit applications of membrane bioreactors (MBRs) for wastewater treatment. Here, powdered activated carbon (PAC) utilization in the formation and performance of a self-forming dynamic membrane consisting of activated sludge and PAC during hybrid wastewater treatment process was studied. Short-term agitation helped (non)biological particles to quickly uniformly settle on mesh filter, forming more uniform PAC-containing dynamic membranes (PAC-DMs). PAC adsorbed adhesive materials, resulting in an increase in average floc size and DM permeability while decreasing biofouling. The most efficient PAC concentration was 4 g L−1 considering techno-economics, i.e. the highest effluent quality (turbidity of 19.89 NTU) and the lowest biofouling (transmembrane pressure rise of 2.89 mbar). Short-term performance of hybrid PAC-DM bioreactor (PAC-DMBR) showed stability in effluent quality improvement including 92%, 95%, 83%, 84% and 98% reductions in turbidity, chemical oxygen demand, total dissolved solids, total nitrogen, and total phosphorous, respectively. Accordingly, adopting hybrid PAC-DMBR has potential to alleviate biofouling and capital cost.

Towards a Better Understanding of Long-Term Self-Forming Dynamic Membrane Bioreactor (SFDMBR) Performance: Effect of Aeration Intensity

This study aims to provide valuable new insights regarding the effect of aeration intensity on long-term self-forming dynamic membrane bioreactor (SFDMBR) performance and the associated mechanisms. Three identical SFDMBRs, with different aeration intensities (i.e., 200, 500 and 800 L/h), were operated in constant transmembrane (TMP) mode for 60 days. The best chemical oxygen demand (COD) removal performance was achieved at medium aeration intensity, owing to the enhanced COD removal contribution by the self-forming dynamic membrane (SFDM). As expected, the SFDM formation time was extended with increasing aeration intensity. Different from the initial short-term stage results, it was interestingly found that the SFDMBR operated at medium aeration intensity exhibited the best long-term filtration performance, followed in order by the SFDMBRs with low and high aeration intensity, respectively. Further analysis revealed that the governing fouling mechanism transited from biomass accumulation to the increase of specific resistance, as aeration intensity increased. The variation of SFDM-specific resistance was verified with particle size distribution (PSD) data and scanning electron microscopy (SEM) images. The long-term increasing rate of SFDM filtration resistance was consistent with both extracellular polymeric substances (EPS) content and the proteins/polysaccharides (PN/PS) ratio of SFDMs. Internal EPS production was enhanced in the thicker SFDM formed at a lower aeration intensity.

Carbon cloth self-forming dynamic membrane enhances anaerobic removal of organic matter from incineration leachate via direct interspecies electron transfer

Anaerobic dynamic membrane bioreactors (AnDMBRs) can convert organic matter in wastewater to methane with excellent filtration performance, and can effectively intercept suspended solids and macromolecules in wastewater. The objectives of this study were to explore the feasibility of enhancing AnDMBRs by using conductive carbon cloth as the supporting material for self-forming dynamic membrane to treat waste incineration leachate, determine the strengthening efficiency and reactor operation mechanism, and further study the enhancement mechanism. Incineration leachate was treated using a laboratory-scale AnDMBR with either conductive carbon cloth or polyester cloth as the supporting material. Compared with the polyester cloth, the carbon cloth reactor resulted in higher COD removal (96.5% vs 85.5%) and higher methane yield (217 vs 169 mL(STP)/h) when the reactors were fed diluted leachate with COD of 15,000 mg/L. In addition, the carbon cloth r withstood a higher organic load of 5.129 kg COD/(m3d) compared with only 4.014 kg COD/(m3d) for the polyester cloth reactor. A suitable filtering performance was also observed in both reactors, which could effectively intercept > 4000 Da macromolecules, and remove > 97% of dissolved organic matter in the leachate. Electroactive microorganisms including Syntrophomonas and Methanothrix species were enriched on the conductive carbon cloth surface, and genes associated with reduction of CO2 to methane were more highly expressed by Methanothrix cells attached to the carbon cloth than that of the polyester cloth, which possibly accelerated the methanogenesis by direct interspecies electron transfer.

An integrated algal membrane photobioreactor as a green-transition technology for the carbon capture and utilization

The harvesting of microalgae strongly affects their effective application as a source of biomass for fuels and chemicals. The aim of this study was the evaluation of the performance of the recently developed Encapsulated Self-Forming Dynamic Membrane (ESFDM) module integrated into a cylindrical photobioreactor (PBR) for the efficient and simultaneous microalgae biomass cultivation and harvesting. The effect of different permeate fluxes was investigated (90–180 L m−2 h−1) obtaining excellent results in terms of harvesting rates (54.23–117.36 g m−2 h−1). Microalgal lipids content was determined under different nutrient regimes, including starvation periods for enhancing the content of lipids. A maximum volumetric biomass productivity of 257 mg L−1d−1 was achieved at a nitrogen content of 15.7 ± 10.6 mg L−1. On the other hand, the highest lipids productivity (42 mg L−1 d−1) was obtained during the starvation phase of nitrogen nutrients. The harvesting rate appeared to be strongly dependent on permeate flux, since the highest permeate flow corresponded in increase of the biomass harvested. The innovative SFDM enormously facilitates microalgae recovery. Indeed, the utilization of the SFDM has been demonstrated as an effective solution to increase the biomass harvesting rate while maintaining biomass concentration inside the photo-bioreactor below 1 g L−1 with a view at ensuring an efficient penetration of light into the membrane photobioreactor (mPBR) and consequently boosting the photosynthetic activity. The simultaneous implementation of the nitrogen starvation strategy can further increase the energy recovery potential from the biomass to address an algal biorefinery approach, besides reducing resources consumption.

Study on the Efficiency of Self-forming Dynamic Membrane Bioreactor on Treatment of Low Concentration Domestic Sewage

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Comparison of the Formation, Filtration Performance, and Structural Characteristic of Self-Forming Dynamic Membranes Under Constant Transmembrane Pressure and Constant Filtration Flux

Comparison of the Formation, Filtration Performance, and Structural Characteristic of Self-Forming Dynamic Membranes Under Constant Transmembrane Pressure and Constant Filtration Flux

Integrated self-forming dynamic membrane (SFDM) and membrane-aerated biofilm reactor (MABR) system enhanced single-stage autotrophic nitrogen removal

The membrane aerated biofilm reactor (MABR) is a novel bioreactor technology, facilitating single-stage autotrophic nitrogen removal. Two laboratory-scale MABRs equipped with non-woven fabrics were operated simultaneously without and with a self-forming dynamic membrane (SFDM) filtration module. After 87 days of operation (system start-up), the reactor incorporated with SFDM filtration showed better performance in terms of total nitrogen removal (>80%) and effluent suspended solid (less than1 mg/L) than the MABR in the up flow anaerobic sludge blanket (UASB) configuration (i.e., without SFDM). The incorporation of SFDM has the ability to retain more slow growing biomass (anammox) inside the reactor. Microbial characterization by 16S rRNA-based amplicon sequencing shows that the abundance and composition of microbial communities in two MABR systems were different, i.e., the genusRhodanobacterwas abundant in UASB-MABR, while Calorithrixwas dominant in SFDM-MABR. PCA-based statistical analysis demonstrated a positive association between reactor performance, membrane characteristics and microbial communities.

Self-forming dynamic membrane filtration for drinking water treatment

Abstract Lab-scale continuous operation of self-forming microfiltration (MF) or ultrafiltration (UF) dynamic membranes were investigated simultaneously by applying iron oxide as an alternative treatment option in those waters having natural organic matter (NOM), iron and manganese. Both dynamic membranes gave high removal rates and effluent concentrations of pollutants were below the limit values in synthetic water. 60 and 62% (of DOC) and 75 and 78% (of UV254) were removed in low dissolved organic carbon (DOC) synthetic (LS) water by MF and UF dynamic membranes, respectively. Although only 42 and 49% (of DOC) and 48 and 53% (of UV254) could be removed by MF and UF dynamic membranes, respectively, a remarkable effect on fouling alleviation was observed in high DOC synthetic (HS) water. Iron oxide did not enhance the removal of organic matter in low DOC natural (LN) water as much as it did in synthetic water. Iron oxide led to the removal of high molecular weight organics, thus reversible fouling was reduced almost 2 orders of magnitude through both types of dynamic membranes in high DOC natural (HN) water. Reversible and irreversible resistances were reduced by iron oxide to some extent in LN water. Nevertheless the effect of iron oxide on fouling alleviation was much higher in HN rather than in LN water.