• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.105-114
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• 2018

Membrane fouling in EC-MBR (Electro-Coagulation aided Membrane Bio-Reactor) processes was evaluated according to the operating parameters, such as current density and contact time. In addition, the fouling mechanism was investigated. Compared to the control (i.e., no electro-coagulation), membrane fouling for filtration of the activated sludge suspension after electro-coagulation was reduced significantly. Membrane fouling was improved further when the contact time was doubled under a low current density of $2.5A/m^2$. On the other hand, membrane fouling was not mitigated further, as expected, even though the contact time was doubled from 12 to 24 hr. at a current density of $10A/m^2$. This indicates that the overall decrease in membrane fouling is a function of the product of the current density and contact time. The particle size of the activated sludge flocs after electro-coagulation was changed slightly, which means that the membrane fouling reduction was not attributed to a larger particle size resulting from electro-coagulation. The experimental confirmed that the dynamic membrane made from aluminum hydroxide, Al(OH)3, and/or aluminum phosphate, Al(PO4), which had been formed during the electro-coagulation, played a key role on the reduction of membrane fouling. The dynamic membrane prevents the particles in the feed solution from deposition to the membrane pores and cake layers. Dynamic membrane formation as a result of electro-coagulation plays a critical role in the mitigation of membrane fouling in EC-MBR.

• Membrane Journal
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• v.25 no.3
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• pp.276-286
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• 2015

The effects of relaxation and backwashing on fouling in ultrafiltration were investigated using full-scale membrane bioreactors (MBRs) which operated at a constant flux of 30 LMH. This paper also estimated the feasibility of using intermittent aeration strategies for minimizing the hydraulic resistance to filtration in comparison with the continuous aeration for running MBRs. Multiple cycles of filtration (14.5 min each) and relaxation (0.5 min each) were repeated. Similarly, a backwash was conducted by replacing a relaxation after each filtration cycle for the comparative performance test. The attached cake thickness on the membrane rapidly increased, caused by subsequent no aeration leading to easier combining with gel layer and the formation of heterogeneous layer on the membrane surface. During periodic backwashing, it is expected that gel and thin cake layer might sufficiently be removed by heterogeneous layer. After periodic backwashing, subsequent cake layer formation during time of no aeration was rapid than frequent no aeration, acting as a prefilter and preventing further irreversible fouling. Based on the Pearson correlation analysis, overall period fouling (dTMP/min) and average of all cycles (dTMP/min) were strongly correlated with the on-off period of aeration for operating MBRs.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.3
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• pp.21-24
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• 2012

In this study, Anaerobic Membrane Bioreactor(AnMBR) treating food waste leachate was operated to investigate treatment efficiency of anaerobic process, operational parameters and production of biogas. AnMBR was operated under the condition of filtration type of inside-out mode. AnMBR was operated under the condition that range of permeate flux was from 15 to 20 LMH and range of transmembrane pressure was from 1 to $3 kgf/cm^2$. It was not good that AnMBR was performed under direct connection between anaerobic reactor and external UF module. so, this connection method changed to indirect connection using buffer tank was placed between anaerobic reactor and UF external module. TCOD and SCOD values were that influent were about 113 g/L, 62 g/L and effluent were 25 g/L, 12 g/L, respectively. also TCOD and SCOD removal efficiency were 77% and 81%, respectively. but after added UF process, COD and SCOD removal efficiency was increased to 93% and 86%, respectively.

• Journal of Environmental Science International
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• v.28 no.10
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• pp.899-905
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• 2019

Recently, an innovative method for wastewater treatment and nutrient removal was developed by combining the sequence batch reactor and membrane bioreactor to overcome pollution caused by shipboard sewage. This system is a modified form of the activated sludge process and involves repeated cycles of mixing and aeration. In the present study, the bacterial diversity and dominant microbial community in this wastewater treatment system were studied using the MACROGEN next generation sequencing technique. A high diversity of bacteria was observed in anaerobic and aerobic bioreactors, with approximately 486 species. Microbial diversity and the presence of beneficial species are crucial for an effective biological shipboard wastewater treatment system. The Arcobacter genus was dominant in the anaerobic tank, which mainly contained Arcobacter lanthieri (8.24%), followed by Acinetobacter jahnsonii (5.81%). However, the dominant bacterial species in the aerobic bioreactor were Terrimonas lutea (7.24%) and Rubrivivax gelatinosus (4.95%).

• Membrane Journal
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• v.31 no.5
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• pp.343-350
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• 2021

In this study the suction pressure was measured with respect to operational time by submersing the multi-bore capillary membrane module in membrane bioreactor(MBR). The hexagonal shape capillary module which has the nominal pore size of 0.2 ㎛, outer diameter of 6.4 or 4.2 mm was immersed in MLSS 8,000 mg/L active sludge aqueous solution, and confirmed changes with respect to permeation flux and air flow rate. It was operated by the filtration/relaxation(FR), FR with backwashing(FR/BW), and sinusoidal flux continuous operation(SFCO) modes. The suction pressure for the SFCO and FR modes was lower at 30 and 50 L/m²·hr, respectively. In addition, the suction pressure of the module with a small outer diameter was relatively low. The suction pressure of a large outer diameter was greatly increased, but it could be reduced by more than 40% by backwashing.

• Membrane and Water Treatment
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• v.12 no.2
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• pp.65-73
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• 2021

Sponge ball cleaning can generate an abrasion effect, which leads to an attractive increasing in both permeate flux and membrane rejection. The aim of this study was to investigate the influence of the daily sponge ball cleaning (SBC) on the performance of different UF cross-flow membrane modules integrated with a bioreactor. Two 1"-membrane modules and one 1/2"-membrane module were tested. The parameters measured and controlled are temperature, pH, viscosity, particle size, dissolved organic carbon (DOC), total suspended solids (TSS), and permeate flux. The permeate flux could be improved by 60%, for some modules, after 11 days of daily sponge ball cleaning at a transmembrane pressure of 350 kPa and a flow velocity of 4 m/s. Rejection values of all tested modules were improved by 10%. The highest permeate flux of 195 L/㎡.h was achieved using a 1"-membrane module with the aid of its negatively charged membrane material and the daily sponge ball cleaning. In addition, the enhancement in the permeate flux caused by daily sponge ball cleaning improved the energy specific demand for all tested modules. The negatively charged membrane showed the lowest energy specific demand of 1.31 kWh/㎥ in combination with the highest flux, which is a very competitive result.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.401-408
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• 2014

In membrane bio-reactor (MBR), the aeration control is one of the important independent variables to decrease fouling and to save energy with shear stress change on the membrane surface. The paper was carried out for numerical simulation of 3-dimensional fluid flow phenomena of the cylindrical bioreactor with submerged flat membranes equipped in the center and supplied the air from the bottom by using the COMSOL program. The viscosity and temperature of solution were assumed to be constant, and the specific air demand based on permeate volume ($SAD_p$) defined as scouring air per permeate rates was used as a variable. The calculated CFD velocities were compared with those of the velocity meter measurement and video image analysis, respectively. The results were good agreement each other within 11% error. For fluid flow in the reactor the liquid velocity increased rapidly between the air diffuser and membrane module, but the velocity decreased during flowing of the membrane module. Also, the velocity increased as it was near from the reactor wall to the central axis. The calculated shear stress on the membrane surface showed the highest value at the center part of the module bottom side and increased as aeration rate increased. Especially, the wall shear stress increased dramatically as the aeration rate increased from 0.15 to 0.25 L/min.

• Journal of Microbiology and Biotechnology
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• v.26 no.9
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• pp.1593-1604
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• 2016

Recently, bacterial quorum quenching (QQ) has been proven to have potential as an innovative approach for biofouling control in membrane bioreactors (MBRs) for advanced wastewater treatment. Although information regarding the microbial community is crucial for the development of QQ strategies, little information exists on the microbial ecology in QQ-MBRs. In this study, the microbial communities of biofilm were investigated in relation to the effect of QQ on anoxic/oxic MBRs. Two laboratory-scale MBRs were operated with and without QQ-beads (QQ-bacteria entrapped in beads). The transmembrane pressure increase in the QQ-MBRs was delayed by approximately 100-110% compared with conventional- and vacant-MBRs (beads without QQ-bacteria) at 45 kPa. In terms of the microbial community, QQ gradually favored the development of a diverse and even community. QQ had an effect on both the bacterial composition and change rate of the bacterial composition. Proteobacteria and Bacteroidetes were the most dominant phyla in the biofilm, and the average relative composition of Proteobacteria was low in the QQ-MBR. Thiothrix sp. was the dominant bacterium in the biofilm. The relative composition of Thiothrix sp. was low in the QQ-MBR. These findings provide useful information that can inform the development of a new QQ strategy.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.7
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• pp.485-491
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• 2011

This study was performed to investigate the characteristics of nutrient removal of municipal wastewater in membrane bioreactor system. Membrane bioreactor consists of four reactors such as two intermittently anaerobic tanks, the oxic tank and the sludge solubilizaion tank with an internal recycle. The hydraulic retention time (HRT) and flux were 6.5 hours and $20.4L/m^2{\cdot}hr$ (LMH), respectively. The removal efficiency of $COD_{Cr}$, SS, TN and TP were 94.0%, 99.3%, 99.9%, 69.9%, and 66.9%, respectively. The estimated true biomass yield, specific denitrification rate (SDNR), specific nitrification rate (SNR), specific phosphorus release rate (SPRR) and specific phosphorus uptake rate (SPUR) were 0.34 kgVSS/kgBOD d, $0.067mgNO_3-N/mgVSS{\cdot}d$, $0.028mgNH_4-N/mgVSS{\cdot}d$, 16.0 mgP/gVSS d and 2.1 mgP/gVSS d, respectively. The contents of nitrogen and phosphorus of biomass were 8.9% and 3.5% on an average.

• Journal of Microbiology and Biotechnology
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• v.26 no.10
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• pp.1746-1754
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• 2016

Recently, spherical beads entrapping quorum quenching (QQ) bacteria have been reported as effective moving QQ-media for biofouling control in MBRs for wastewater treatment owing to their combined effects of biological (i.e., quorum quenching) and physical washing. Taking into account both the mass transfer of signal molecules through the QQ-medium and collision efficiencies of the QQ-medium against the filtration membranes in a bioreactor, a cylindrical medium (QQ-cylinder) was developed as a new shape of moving QQ-medium. The QQ-cylinders were compared with previous QQ-beads in terms of the QQ activity and the physical washing effect under identical loading volumes of each medium in batch tests. It was found that the QQ activity of a QQ-medium was highly dependent on its specific surface area, regardless of the shape of the medium. In contrast, the physical washing effect of a QQ-medium was greatly affected by its geometric structure. The enhanced anti-biofouling property of the QQ-cylinders relative to QQ-beads was confirmed in a continuous laboratory-scale MBR with a flat-sheet membrane module.