• Journal of Korean Society of Water and Wastewater
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• v.27 no.3
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• pp.339-349
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• 2013

Biological treatment of RO concentrate from wastewater reuse process is known to be very difficult due to its high concentration of non-degradable organics and salt ions such as chloride, nitrate and phosphate. In this research, the treatment performance of MBR was examined using RO concentrate mixed with raw wastewater as the influent of MBR. Addition of PAC (powdered activated carbon) to MBR was also evaluated in order to enhance the treatment performance and stability. The performance of MBR for treating only RO concentrate decreased gradually although external carbon source was added. The average removal performance of MBR with and without PAC decreased from 99.1 %(98.8 %) to 94.9 %(91.4 %) for COD, 81.3 %(80.3 %) to 42.0 %(41.9 %) for T-N and 57.3(55.0 %) to 30.0 %(21.0 %) for T-P with the increase of RO concentrate mixing rate of 0 % to 20 % in the feed water. Addition of PAC showed positive effect on the performance of MBR for the removal of COD and phosphorus in case that the ratio of RO concentrate to feed water increased.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.5
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• pp.545-551
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• 2016

This study compares characteristic of membrane fouling in MBR-RO systems. In lab. scale MBRs test, MBRs were operated at different Flux(10, 20, 30 & 40 LMH) and temperature(10, 15, 20, 25 & $30^{\circ}C$). The results show that MBR permeate was measured lower amounts of organic substances in Higher flux and lower temperature and led to lower RO fouling rates. The main cause was that due to cake fouling formed on membrane surfaces in MBRs. Under both cases, Cake layer of membrane surfaces formed in MBRs removed RO fouling factors, polysaccharide and protein, because of cake layer attached on membrane surfaces greater amounts of organic substances. This study implies that optimization of MBR with operating conditions is a crucial strategy to RO membrane fouling control.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.521-526
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• 2006

A membrane bioreactor (MBR) is an effective tool for wastewater treatment with recycling. MBR process has several advantages over conventional activated sludge process (ASP); reliability, compactness, and quality of treated water. The resulting high-quality and disinfected effluents suggest that MBR process can be suitable for the reused and recycling of wastewater. An anoxic/oxic (A/O) type MBR was applied to simultaneous removal of organics and nutrients in sewage. At first, the efficiency of submerged MBR process was investigated using a hollow fiber microfiltration membrane with a constant flux of $10.2L/m^2{\cdot}h$ at each solids retention time (SRT). Results showed that protein/carbohydrate (P/C) ratio increased and total extracellular polymeric substances (EPS) remained constant with SRT increased. Secondly, A/O type MBR with a reverse osmosis (RO) membrane was employed to treat the municipal wastewater. The performance of A/O type MBR-RO process is better for the treatment of organics and nutrients than ASP-MF-RO process in terms of consistent effluents quality.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.6
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• pp.407-414
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• 2013

Full scale livestock wastewater treatment plant (100 t/d) was constructed and operated to develop compact and cost effective treatment process for public plant as well as individual farm. Liquid form of livestock wastewater after belt press filter was treated through MBR/NF/RO. NF/RO brine water was mixed with livestock wastewater sludge and treated using denitrification, coagulation and air flotation process. Mixed effluent of NF/RO and air flotation meet public livestock wastewater treatment standard, BOD, T-N and T-P, 30 mg/L, 60 mg/L, 8 mg/L below, respectively. Condensed sludge of air flotation returned belt press filter. Dewatered cake contained 90% water and could be used fertilizer after mixing sawdust.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1391-1398
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• 2010

Reuse feasibility of MBR effluent of S Electronic Company's organic wastewater as a LCD process water was investigated by a $32m^3/d$ pilot-scale RO membrane process. The effects of operating pressure and permeate flux at constant 85% recovery of RO membrane process using MBR effluent were analyzed for transmembrane pressure and period for CIP by membrane fouling as well as rejection of TOC and conductivity. MBR effluent requires additional treatment to meet the LCD process water quality criteria of TOC<1 mg/L and conductivity<$100{\mu}S/cm$ which is stringent as compared with those of conventional reuse water quality criteria. The RO process operated at 85% recovery with stepwise increasing of permeate fluxes from 12.5 LMH to 22.0 LMH was able to meet LCD process water quality criteria. However, the transmembrane pressure increased and the period of CIP decreased as increasing permeability fluxes due to fouling of RO membrane. The optimum operational conditions of RO membrane process were permeate fluxes of 16.5~18.5 LMH with operating pressure of $6.7{\sim}12.4kgf/cm^2$ and CIP period of 20~25 days at constant 85% recovery.

• Membrane Journal
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• v.24 no.2
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• pp.142-150
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• 2014

This paper is to develop the process suitable for the advanced treatment of liquid fertilizer from the livestock night soil treatment facility (biogas plant). Nanofiltration (NF) and reverse osmosis (RO) process was used, respectively, for the advanced treatment of liquid fertilizer. And membrane bioreactor (MBR) with and without biomedia were tested, respectively, for the pretreatment. It was found that almost T-N of the liquid fertilizer was composed of ammoniacal nitrogen. Transmembrane pressure of MBR with biomedia increased slowly during the operation time, while that of MBR without biomedia increased rapidly at the initial time. But there was no difference observed in the removal efficiencies of COD, T-N, and T-P irrespective of the dosage of biomedia. When the liquid fertilizer was pretreated by MBR with biomedia, the removal efficiencies of COD, T-N, and T-P were 99.8, 86.5%, and 99.8% by NF, and 99.9, 86.8%, and 99.8% by RO, respectively. Compared with the effluent quality standards of the livestock night soil treatment facility, the water quality treated by MBR and NF/RO process met the standard for COD and T-P, but exceeded the permitted standard for T-N. In order to meet the effluent quality standard for T-N, it is necessary to change the MBR operation cycle or to add the secondary treatment by NF/RO.

• Journal of the Korean GEO-environmental Society
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• v.8 no.6
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• pp.21-28
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• 2007

The objective of this study was to investigate the effect of hydraulic retention time (HRT) on removal efficiencies of organic matter, nitrogen and phosphorus in MBR-RO process for treating synthetic sewage. In MBR process, turbidity was less than average 2 NTU and average removal efficiency showed more than 99% during the operation period(MBR 105 day). As a result of HRT variation, average removal efficiencies of $COD_{Cr}$ on HRT 6, 12, 18 and 24hour were about 72.4, 84, 88.6 and 92.5%, respectively. The $NH_4{^+}-N$ removal efficiency was about 60.2 85.5, 91.3 and 92.2%, respectively. T-N and T-P removal efficiencies increased from 53.7 and 56.8 to 82.5 and 86.4%, respectively as the HRT increased from 6 hour to 24 hour. In RO process, average removal efficiencies of color and $COD_{Cr}$ in RO permeate were about 99.9% and 96.8%, respectively. Also, removal efficiencies of T-N, $NH_4{^+}-N$, $NO_3{^-}-N$ and T-P were all above average 90%.

• Membrane and Water Treatment
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• v.6 no.6
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• pp.489-499
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• 2015

In this work, treatment of real hypersaline refinery wastewater by hollow fiber membrane bioreactor coupled with reverse osmosis unit was studied. The ability of HF-MBR and RO developed in this work, was evaluated through examination of the effluent properties under various operating conditions including hydraulic retention time and flux. Arak refinery wastewater was employed as influent of the bioreactor which consists of an immersed ultrafiltation membrane. The HF-MBR/RO was run for 6 months. Average elimination performance of chemical oxygen demand, biological oxygen demand, total suspended solids, volatile suspended solids, total dissolved soild and turbidity were obtained 82%, 89%, 98%, 99%, 99% and 98% respectively. Highly removal performance of oily contaminant, TDS and the complete retention of suspends solids implies good potential of the HF-MBR/RO system for wastewater refinement.

• Membrane and Water Treatment
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• v.6 no.6
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• pp.477-488
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• 2015

This study demonstrates that low pressure membranes are the ideal choice for industrial and/or municipal wastewater treatment by showing some promising experimental results, understanding different membrane filtration models, studying the potential of membrane bioreactors (MBRs), considering ceramic membranes fabrication and illustrating the role of nanotechnology in membranes. Cost study calculations are included to determine the treatment cost as well as the initial cost of various membrane types. Results showed that integrated membranes are preferred over MBR in case of average capacities. However, higher capacity situations are the most economical choice for MBR. It is shown that the least treatment cost in MBR was about $0.13/m^3$. However, the $0.13/m^3$ is the theoretical cost which is very small compared to the actual average MBR treatment cost of $0.5/m^3$.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.2
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• pp.111-119
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• 2019

Electro-coagulation process has been gained an attention recently because it could overcome the membrane fouling problems in MBR(Membrane bio-reactor). Effect of the key operational parameters in electro-coagulation, current density(${\rho}_i$) and contact time(t) on membrane fouling reduction was investigated in this study. A kinetic model for ${\rho}_i$ and t required to reduce the membrane fouling was suggested under different MLSS(mixed liquor suspended solids) concentration. Total 48 batch type experiments of electro-coagulations under different sets of current densities(2.5, 6, 12 and $24A/m^2$), contact times(0, 2, 6 and 12 hr) and MLSS concentration(4500, 6500 and 8500mg/L) were carried out. After each electro-coagulation under different conditions, a series of membrane filtration was performed to get information on how much of membrane fouling was reduced. The membrane fouling decreased as the ${\rho}_i$ and t increased but as MLSS decreased. Total fouling resistances, Rt (=Rc+Rf) were calculated and compared to those of the controls (Ro), which were obtained from the experiments without electro-coagulation. A kinetic approach for the fouling reduction rate (Rt/Ro) was carried out and three equations under different MLSS concentration were suggested: i) ${\rho}_i^{0.39}t=3.5$ (MLSS=4500 mg/L), ii) ${\rho}_i^{0.46}t=7.0$ (MLSS=6500 mg/L), iii) ${\rho}_i^{0.74}t=10.5$ (MLSS=8500 mg/L). These equations state that the product of ${\rho}_i$ and t needed to reduce the fouling in certain amounts (in this study, 10% of fouling reduction) is always constant.