This study was conducted to simulate the lifetime of the membrane by analyzing the performance of the membrane degraded by chlorine. Chlorine exposure under several conditions caused the degradation of the membrane, resulting in the absence of any salts and an extreme increase in permeability. When the n value was calculated and compared through CnT analysis and CTn analysis, the p values were all less than 0.005, but CTn analysis, which had a higher R2 value, was adopted to simulate the membrane lifetime. Power coefficients take on values higher than 1, indicating that the exposure time to chlorine has a greater influence on membrane deterioration than the chlorine exposure concentration at 20℃ and 30℃. In particular, the process should be operated at less than 0.5 ppm at 30°C, and the chlorine exposure time of 1 cycle should be set to within 15 hours. In addition, the sensitivity to chlorine increased by 10.5 to 12.2 times when the chlorine exposure temperature increased by 10°C through the correlation between the chlorine exposure cycle and membrane lifetime. The membrane lifetime investigated in this study is only an estimated value, entirely because of chlorine membrane deterioration, excluding raw water characteristics and the type of detergent. Accordingly, it is considered that the membrane lifetime simulation can be applied by comparing the membrane performance with the actual process based on the filtration performance of membrane deterioration by chlorine.

This study was conducted to evaluate the filtration performance according to the feed temperature composed of NaCl and the operating pressure of the brackish water reverse osmosis (BWRO) process. The temperature is known that decides the filtration performance of reverse osmosis (RO). It is noted that temperature increase activates the permeate of salts due to augment of diffusivity and mass transfer. Filtration of the lab-scale RO system was performed with constant pressure and the constant flow was simulated. The salt rejection measured by the concentration of the feed and permeate was compared with water permeability and salt permeability in the conditions containing various temperatures (5, 10, 15, 20, 25, and 30℃) and pressures (10, 12, 15, and 18 bar). An increase in feed temperature from 5 °C to 30 °C caused a 4.65% decrease in salt rejection in CSM, due to an increase in salt permeability (4.06 times) rather than an increase in water permeability (2.62 times). Specific energy consumption (SEC) was calculated by using an electricity meter set in the RO system. It was expected that the SEC by the increases in temperature and pressure decreased due to the viscosity decline of the feed and the permeate flux augment, respectively. The SEC decreased by 63.4% in CSM and by 54.3% in Nittodenko when the feed temperature increased from 5 °C to 30 °C. It discussed how to operate the optimal RO process through the effect of temperature and operating pressure and the comparison of SEC.

In this study, chemically enhanced steam cleaning(CESC) was applied as a novel and efficient method for the control of organic and inorganic fouling in ceramic membrane filtration. The constant filtration regression model and the resistance in series model(RISM) were used to investigate the membrane fouling mechanisms. For total filtration, the coefficient of determination(R2) with an approximate value of 1 was obtained in the intermediate blocking model which is considered as the dominant contamination mechanism. In addition, most of the coefficient values showed similar values and this means that the complex fouling was formed during the filtration period. In the RISM, Rc/Rf increased about 4.37 times in chemically enhanced steam cleaning compared to physical backwashing, which implies that the internal fouling resistance was converted to cake layer resistance, so that the membrane fouling hardly to be removed by physical backwashing could be efficiently removed by chemically enhanced steam cleaning. The results of flux recovery rate showed that high-temperature steam may loosen the structure of the membrane cake layer due to the increase in diffusivity and solubility of chemicals and finally enhance the cleaning effect. As a consequence, it is expected that chemically enhanced steam cleaning can drastically improve the efficiency of membrane filtration process when the characteristics of the foulant are identified.

Forward osmosis (FO) has emerged as one of the most promising technologies for seawater desalination. Despite the progress in membrane technology, draw solutions are still limited in terms of its reusability thereby hampering its economic viability. Hydrophilic ILs can be easily dissolved in water to constitute a DS. ILs are environmentally benign due to their high thermal stability and negligible vapor pressure. Hydrophilic ILs can be easily dissolved in water to constitute a DS. ILs are environmentally benign due to their high thermal stability and negligible vapor pressure. This work was supported by NRF funded by the Korea government funded by the Ministry of Science and ICT (2016R1A2B1009221 and 2017R1A2B2002109) and Ministry of Education (2009-0093816 and 22A20130012051(BK21Plus)).

Membrane fabrication is a critical area that hampers forward osmosis (FO) technology from industrialization. Herein, electrospun poly(vinyl alcohol) (PVA) nanofiber (NF) was used as a support layer for thin film composite (TFC) FO membrane. The PVA NF was incorporated with sulfonated graphene oxide (sGO). The oxygenous-rich sGO enhanced the hydrophilicity and mechanical strength of PVA NF as revealed by contact angle and tensile strength measurements, and pure water flux. On this support, the active polyamide layer was formed through interfacial polymerization. Meanwhile, FO performance of sGO/PVA TFC membrane is currently being evaluated. This work was supported by NRF of Korea funded by the Ministry of Science and ICT (2016R1A2B1009221 and 2017R1A2B2002109) and Ministry of Education (2009-0093816 and 22A20130012051 (BK21Plus)).

In this study, the effect of chemically enhanced backwash(CEB) coping with algal(Heterosigma Akashiwo) inflow was evaluated in the seawater desalination pretreatment process using ceramic membrane. In order to confirm the possibility of long-term filtration operation, the recovery rate of transmembrane pressure(TMP) due to the CEB using NaOCl was examined. When the membrane flow rate was 83.3 LMH, the TMP was maintained within 200 kPa for 84 hours in seawater influent. As the algal counts of 30,000 cell/mL were injected into the influent of seawater, however, the TMP rapidly increased and exceed maximum value. Membrane fouling caused by the algae was very poorly recovered by usual physical backwash. The CEB was performed for 30 min(3 min circulation / 27 min immersion) with 300 mg/L of NaOCl. As a result of the CEB application, it was possible to maintain a stable operating of filtration during 10 days and the average recovery rate of TMP by the CEB was 98.1%. It has been confirmed that the CEB using NaOCl is very effective in removal of membrane fouling by algae, resulted in stable membrane filtration for the long-term operation.

In this study, the effects of operating conditions on the formation of reversible and irreversible fouling were investigated in the filtration using ceramic membrane for water treatment process. The effect of coagulation pretreatment on fouling formation was also evaluated by comparing the performance of membrane filtration both with and without addition of coagulant. A resistance-in-series-model was applied for the analysis of membrane fouling. Total resistance (RT) and internal fouling resistance (Rf) increased in the membrane filtration process without coagulation as membrane flux and feed water concentrations increased. Internal fouling resistance, which was not recovered by physical cleaning, was more than 70% of the total resistance at the range of the membrane flux more than 5 m3/m2･day. In the combined process with coagulation, the cake layer resistance (Rc) increased to about 30-80% of total resistance. As the cake layer formed by coagulation floc was easily removed by physical cleaning, the recovery rate by physical cleaning was 54~90%. It was confirmed from the results that the combined process was more efficient to recover the filtration performance by physical cleaning due to higher formation ratio of reversible fouling, resulted in the mitigation of the frequency of chemical cleaning.

In water treatment process using microfiltration membranes, manganese is a substance that causes inorganic membrane fouling. As a result of analysis on the operation data taken from I WTP(Water Treatment Plant), it was confirmed that the increase of TMP was very severe during the period of manganese inflow. The membrane fouling fastened the increase of TMP and shortened the service time of filtration or the cleaning cycle. The TMP of the membrane increased to the maximum of 2.13 kgf/cm2, but it was recovered to the initial level (0.17 kgf/cm2) by the 1st acid cleaning step. It was obvious that the main membrane fouling contaminants are due to inorganic substances. As a result of the analysis on the chemical waste, the concentrations of aluminum(146-164 mg/L) and manganese(110-126 mg/L) were very high. It is considered that aluminum was due to the residual unreacted during coagulation step as a pretreatment process. And manganese is thought to be due to the adsorption on the membrane surface as an adsorbate in feed water component during filtration step. For the efficient maintenance of the membrane filtration facilities, optimization of chemical concentration and CIP conditions is very important when finding the abnormal level of influent including foulants such as manganese.

In this study, it is estimated that ceramic membrane process which can operate stably in harsh conditions replacing existing organic membrane connected with coagulation, sedimentation etc. . Jar-test was conducted by using artificial raw water containing kaolin and humic acid. It was observed that coagulant (A-PAC, 10.6%) 4mg/l is the optimal dose. As a results of evaluation of membrane single filtration process (A), coagulation-membrane filtration process (B) and coagulation-sedimentation-membrane filtration process (C), TMP variation is stable regardless of in Flux 2 m3/m2･day. But in Flux 5 m3/m2･day, it show change of 1-89.3 kpa by process. TMP of process (B) and (C) is increased 11.8, 0.6 kpa each. But, the (A) showed the greatest change of TMP. When evaluate (A) and (C) in Flux 10 m3/m2･day, TMP of (A) stopped operation being exceeded 120 kpa in 20 minutes. On the other hand, TMP of (C) is increased only 3 kpa in 120 minutes. Through this, membrane filtration process can be operated stably by using the linkage between the pretreatment process and the ceramic membrane filtration process. Turbidity of treated water remained under 0.1 NTU regardless of flux condition and DOC and UV254 showed a removal rate of 65-85%, 95% more each at process connected with pretreatment. Physical cleaning was carried out using water and air of 500kpa to show the recovery of pollutants formed on membrane surface by filtration. In (A) process, TMP has increased rapidly and decreased the recovery by physical cleaning as the flux rises. This means that contamination on membrane surface is irreversible fouling difficult to recover by using physical cleaning. Process (B) and (C) are observed high recovery rate of 60% more in high flux and especially recovery rate of process (B) is the highest at 95.8%. This can be judged that the coagulation flocs in the raw water formed cake layer with irreversible fouling and are favorable to physical cleaning. As a result of estimation, observe that ceramic membrane filtration connected with pretreatment improves efficiency of filtration and recovery rate of physical cleaning. And ceramic membrane which is possible to operate in the higher flux than organic membrane can be reduce the area of water purification facilities and secure a stable quantity of water by connecting the ceramic membrane with pretreatment process.

Ionic liquids (ILs) are potential drawing agents in forward osmosis (FO) due to their high ionicity, low vapor pressure and high solubility. A series of ILs were investigated as draw solutes for FO application and were compared with NaCl. Water (Jv )and reverse (Js) fluxes were evaluated using commercially available HTI-CTA membrane via FO and PRO modes. FO runs were conducted using 0.3M draw solution and DI water as feed. Results reveal that ILs like BMIM acetate, BMIM bromide and N4444 acetate were able to generate high Jv but with negligible Js. This demonstrates the potential of certain ILs as FO drawing agents. This research was supported by NRF through the Ministry of Science, ICT & Future Planning (No.2016R1A2B1009221) and through Basic Science Research Program of Ministry of Education(2009-0093816).

The occurrence of objectionable tastes and odors in drinking water is a common and widespread problem. The most troublesome odors are usually those described as muddy or earthy-musty. Two organic compounds which have been implicated as the cause of earthy-musty odor problems in water are geosmin and 2-Methylisoborneol. These earthy-musty organics have been shown to be metabolites of actinomycetes and blue green algae. The purpose of this paper is to describe adsorbability in removing these two oder causing compounds(geosmin and 2-MIB) upon various conditions like pH variation, adding humic acid and different activated carbon. The conclusion of this study are as followings. In batch test, carbon dosage is 10mg/100ml for geosmin and 15mg/100ml for 2-MIB. Both were in equilibrium state after 60 hours. In model simulation, F-P model described experiment data and modelling data appropriately in geosmin but F-S model not. In case of 2-MIB, models didn't describe relation between experiment and modelling data well. Two causative agents of earthy-musty odor compounds, geosmin and 2-MIB, are strongly adsorbed by activated carbon either coconut or brown. There appears to be no effect of pH (3,7,9) on adsorption of these two organics. Activated carbon proved to be more effective for removing geosmin than for removing 2-MIB. When activated carbon is. used in removing these two organics, the removal of these appeared to be adversely affected by back ground organic compounds, such as humic substances, due to competitive adsorption.

용해성 무기전자수용체를 이용하여 호흡하는 황산염환원박테리아는 지반환경에서 다양한 물질의 생화학적 순환에 중요한 역할을 담당한다. 하지만 용해되지 않는 고형전자수용체를 이용하여 전자를 전달하는 황산염환원균은 현재까지 보고된 바 없다. 따라서 본 연구에서는 혐기성미생물로서 대표적인 황산염환원균주 Desulfovibrio desulfuricans 가 고형전자수용체로의 직접적인 전자전달을 위해 나노크기의 필라멘트를 생성하는 것을 확인하였다. 이러한 나노필라멘트는 전기전도도가 높게 나타나(5.81 S·m-1) 이를 이용하여 황산염환원균이 고형전자수용체로 전자를 전달할 수 있음이 입증되었다. 이 같은 기작을 이용하여 황산염환원균은 미생물연료전지(Microbial fuel cell)에서 전기생산을 위한 고체전극으로의 직접적 전자전달을 수행함을 확인하였다. 이러한 결과는 황산염환원균에 의해 용해성 전자수용체의 유효성이 제한될 때, D. desulfuricans 와 같은 황산염환원균이 용해되지 않는 고형전자수용체로의 전자전달을 위한 대체방안으로 전도성 나노규모의 박테리아 부속물생산을 개시함을 의미한다. 따라서 황산염환원균 중 일부는 전자 매개체없이 직접적으로 고형전자수용체로의 전자전달을 수행할 수 있으며, 황산염환원균주에 의한 효과적인 전기생산을 증진시키는 기법으로 MFC 연구에 유용할 것으로 판단된다.

본 연구에서는 sigle-walled carbon nanotube (SWCNTs)에 재조합된 고정산화효소를 부착한 고정효소제제를 이용하여 방향족 탄화수소의 생화학적 분해를 고찰하였다. Arthrobacter chlorophenolicus A6로부터 복제 및 대량발현 하여 얻어진 hydroquinol 1,2-dioxygenase는 방향족 탄화수소의 ring-fission를 활성화하는 것으로 나타났다. 이와 같이 재조합되어 획득된 dioxygenase를 SWCNTs에 고정시켰다. SWCNTs의 표면은 비이온계 계면활성제로 표면처리/활성화하였고, 이를 통해 SWCNTs의 수용액상 dispersivity가 크게 증가함을 확인하였다. 고정화 수율은 62%였고, 효소고정이후 효소활성도의 60-70%가 유지되었다. 효소의 동역학적 분석 결과, 기질이용률(Vmax)과 촉매효율(Vmax/KM)의 측면에서 고정된 효소는 동역학적 특성이 거의 유사하게 나타나 고정된 효소의 활성도 손실이 최소한으로 유지될 수 있음을 알 수 있었다. 고정화 된 효소는 pH, 온도, 이온강도의 변화에도 자유 효소보다 더 높은 안정도를 유지하는 것으로 나타났다. 또한, 효소 재사용 시에도 활성도가 높게 유지되는 것으로 나타났다. 이러한 결과들은 계면활성제를 이용한 SWCNTs의 표면처리 및 효소고정 기법이라는 새로운 효소 고정화 기술 개발에 적용할 수 있을 것으로 기대된다. 또한, 본 연구에서의 CNT를 이용한 효소고정제재를 이용한 고효율의 친환경적, 경제적인 난분해성 유기오염물질의 생화학적 분해 기법 개발의 기초를 제공할 것으로 기대된다.

산업단지, 철도부지, 사격장 및 폐광산 등 중금속으로 오염된 토양부지의 복원을 위하여 토양 세척법, 세정법, 동전기법 등의 기술이 사용되며, 이들 기술의 적용을 위해서는 강한 산 또는 화학적 산화제의 사용이 불가피하다. 화학적 세척제의 사용은 처리수의 정화 및 처리 토양의 생태 독성 제거 등 후처리가 필요하다. 한편, 휴믹산은 자연 토양 내 많이 존재하는 자연기원 유기물로서, 비료로 사용되거나 토양 개질에도 많이 이용된다. 이러한 휴믹산은 구조가 매우 복잡하며, 중금속과 배위결합이 가능한 카르복실기, 페놀기 등을 다량 보유한다고 알려져있다. 휴믹산 중금속 제거를 위한 킬레이트제로 친환경적 토양 세척법으로의 적용이 가능하다. 본 연구는 표준 휴믹산을 정제하여 용산 철도부지의 현장오염토양을 대상으로 구리, 납, 아연의 제거를 위한 토양 세척법의 적용 가능성을 평가하였다. 농도 및 pH 조건을 달리한 실험 결과 농도는 1000 ppm에서, pH 조건 10에서 각 중금속의 제거 효율이 가장 높게 나타났다. 중금속 제거용 킬레이트제의 대조군으로 EDTA를 사용하였으며, 휴믹산의 중금속 제거율은 EDTA 대비 구리, 납, 아연 각각 20.44%, 4.58%, 19.55%으로 나타났다. 토양 세척 시의 고액 비, 반응 온도, 등 다른 환경인자에 따라 중금속 제거 효율을 증대 시킬 수 있을 것으로 판단된다.