Han-Seung Kim

Effect of driving pressure and recovery rate on the performance of nanofiltration and reverse osmosis membranes for the treatment of the effluent from MBR

AbstractThis research was carried out to evaluate the suitable operating condition for both nanofiltration (NF) and reverse osmosis (RO) membranes for the reuse of wastewater effluent from membrane bioreactor (MBR). Various parameters such as pH, conductivity, total dissolved solids, UV254, dissolved organic carbon, total nitrogen and total phosphorus were analysed for the permeate from the NF and RO to compare the membrane performance. Batch experiments were conducted using a lab-scale NF and RO systems. Effluent from the MBR system treating synthetic wastewater was used as feed water to NF and RO. Filtration tests were performed at the operating pressure ranging from 0.2 to 1.0 MPa. Flux was measured at every 5 min, and the permeate was collected at the end of each experiment. Although the permeate flux and salt rejection increased in proportion to the operating pressure for NF, the increase in salt rejection was tapered off at a certain range of the operating pressure over 0.6 MPa for RO. As a result, ...

Nitrification denitrification enhanced biological phosphorous removal (NDEBPR) occurs in a lab-scale alternating hypoxic/oxic membrane bioreactor

Strict anaerobic or anoxic maintenance of the system and process susceptibility to low organic loading are major concerns in nitrification denitrification enhanced biological phosphorous removal (NDEBPR). The study has initiated NDEBPR in a lab-scale alternating hypoxic/oxic membrane bioreactor by developing an enhanced mixed microbial culture capable of removing 97±2% COD, 99±0.84% NH(3)-N, 90±3% TN, and 96±1% TP-PO(4)(3-) with 20-day SRT. The viable cells ranging from 1.6×10(8) to 2.0×10(8)cells/ml estimated from the total bacterial genomic DNA (6.43-7.83 μg DNA/ml) represented only 5% of the MLVSS indicating low microbial biomass concentration. Reducing the organic load from 1250 to 750 mg COD/ml as glucose did not deteriorate the effluent quality (3.77±1.0 mg N-TN/l; 0.08±0.24 mg NH(3)-N/l; and 0.32±0.10 mg PO(4)(3-)-P/l). These observations are characteristics of activated sludge that harbors denitrifying polyphosphate accumulating organisms (DPAOs). The results showed that NDEBPR can be achieved under alternating hypoxic/oxic conditions.

Effect of powdered activated carbon on integrated submerged membrane bioreactor-nanofiltration process for wastewater reclamation.

The aim of this study was to determine the effect of powdered activated carbon (PAC) on the overall performance of a submerged membrane bioreactor (SMBR) system integrated with nanofiltration (NF) for wastewater reclamation. It was found that the trans-membrane pressure of SMBR increased continuously while that of the SMBR with PAC was more stable, mainly because water could still pass through the PACs and membrane even though foulants adhered on the PAC surface. The presence of PAC was able to mitigate fouling in SMBR as well as in NF. SMBR-NF with PAC obtained a higher flux of 8.1 LMH compared to that without PAC (6.6 LMH). In addition, better permeate quality was obtained with SMBR-NF integrated process added with PAC. The present results suggest that the addition of PAC in integrated SMBR-NF process could possibly lead to satisfying water quality and can be operated for a long-term duration.

Fouling characteristics of microfiltration membranes by organic and inorganic matter and evaluation of flux recovery by chemical cleaning

AbstractCharacteristics of membrane fouling by organic and inorganic foulants and flux recovery by chemical cleaning were investigated in this study. Three kinds of raw water with organic matter (15 mg/L humic acid), with inorganic matter (1 mg/L Fe and 1 mg/L Mn) and a mixture of organic and inorganic matter (humic acid, Fe and Mn) were tested. The effects of Ca2+ and pH on fouling were also investigated as well as efficiency of chemical cleaning. The results showed that raw water with the mixture reduced the final flux by 10%. On the other hand, the final fluxes were reduced by 8% for inorganic matter and by 78% for organic matter. Although, FI decreased with the existence of Ca2+ in the mixture of humic acid, Fe and Mn, flux was recovered easily by backwashing because Ca formed a cake layer by chelating with humic substances. However, pre-treatment with sodium hypochlorite reduced the flux severely for raw water containing inorganic matter. Acid (2% nitric acid) and base (1% sodium hydroxide), were use...

Effect of operating conditions on the treatment of brackish groundwater by electrodialysis

Abstract Desalination of brackish groundwater by electrodialysis was examined in this study. Groundwater samples were taken from a coastal area in Korea where the intrusion of seawater to groundwater is significant. The ion concentrations of the samples were 1,288 mg/L for Cl–, 107 mg/L for , 273 mg/L for Na+, 118 mg/L for Mg2+, 201 mg/L for Ca2+, and 4.7 mg/L for K+, and electric conductivity was 3.85mS/m. Operating conditions are as follows: applied voltage (from 5 to 30 V), pH (3, 7, 9), concentration of electrolyte solution (from 0 to 10% as Na2SO4), flow rate of dilute/concentrate/electrolyte (1.08, 2.16, 3.24 L/min)/(1.08, 2.16, 3.24 L/min)/(1.68, 3.36, 5.04 L/min). Cations and anions of water samples were analyzed using ion chromatography (Alltech). The rapid increase in the removal of salt ions was observed until a certain level of removal reached. The higher removal was achieved as the applied voltage increased and linear increase in the removal was found as the voltage increased up to 20 V, whil...

Biological degradation of dissolved organic carbons and ammonia oxidation by biological activated carbon in PAC and membrane applied process

Abstract Membrane filtration process has been developed to overcome the weakness of conventional water treatment process for the removal of particulates and some pathogens such as cryptosporidium and giardia. Although suspended particulate, including pathogens and bacteria, can be effectively removed by membrane, the trace organics and soluble matters are hard to remove. To overcome this limitation, membrane filtration is required to be associated with other technologies such as adsorption and oxidation. PAC membrane retrofitting (PMR) process is one of the new processes for removing not only particulate but also soluble matters. PMR process consists of a coarse powder-activated carbon (C-PAC) contactor and a subsequent submerged membrane tank. Powdered activated carbon (PAC) with high concentrations of 30,000 mg L−1 is suspended as a slurry blanket in the PAC contactor and soluble matters are removed by the slurry blanket. Most particulates are separated by the membrane. Membrane module used in this stud...

Treatment of reverse osmosis concentrate by electrolysis and MBR process

AbstractIn this study, the reverse osmosis (RO) concentrate treatment technology, which combines the electrolysis process with the MBR process, has been suggested to treat the RO concentrate generated in the water recycle process, which applied the RO membrane. The electrolysis process constructed in this study is to reduce the MBR process load by removing the non-degradable matters and the nitrogen compound, which are the weakness of biological treatment. When treating the RO concentrate through the electrolysis, the disinfection by-products—like residual chlorine, THMs and so forth—are generated. Since this reaction of the by-products affects the microbes, PAC was injected within the MBR reactor to desalinate the treated water. As the MBR process shows considerably high treatment efficiency for the organic matters and can increase the concentration of the activated sludge within reactor, it is effective to treat the nitrogen and phosphorus, which cause the eutrophication of water, but since there is a l...

Effect of various pretreatments on the performance of nanofiltration for wastewater reuse

AbstractIn the present study, we focused on integrated processes by membrane bioreactor (MBR), SMR, and pressurized microfiltration (PMF) as a pretreatment with nanofiltration (NF) as a post-treatment for wastewater reuse. The purpose of this study is to treat wastewater through MBR, MBR with powdered activated carbon (PAC), submerged microfiltration (SMF), SMF with PAC, and PMF effluent, which is mainly used in wastewater treatment, in combination with NF as a post-treatment process. MBR with PAC was used as the main pretreatment for NF, and was compared to NF combined with other pretreatments. At constant pressure in NF, MBR-NF with PAC system has higher flux and better water quality than other systems. In order to prevent the membrane fouling by organic matters, the integrated MBR with PAC process should be employed. The integrated MBR-NF with PAC process can improve water quality for wastewater reuse. Based on the wastewater reuse standards, effluent can be available for human application. Advanced tr...