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Concentration Polarization Phenomena in Commercial Spiral-Wound RO Membrane
( Thiruvenkatachari Ramesh ) 조선대학교 공학기술연구원 2009 공학기술논문지 Vol.2 No.3
The effect of feed temperature on flux decline in commercial spiral wound membrane was investigated for analyzing polarization concentration. An unsteady-state model was formulated by employing the non-conservative mass balance equation in the feed channel. The model was checked for numerical stability and convergence under various feed and operating conditions such as concentration, temperature, pressure, and element numbers. The model results were verified experimentally using a 2.5 inch pilot-scale spiral wound reverse osmosis (RO) unit with a processing capacity of 1.47 m3/d. It was found that the time-dependent model proposed in this work can be successfully applied for the analysis of long-term flux decline due to fouling and membrane degradation.
A review on UV/TiO2 photocatalytic oxidation process
Ramesh Thiruvenkatachari,Saravanamuthu Vigneswaran,문일식 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.1
Advanced oxidation processes (AOPs) with UV irradiation and photocatalyst titanium dioxide (TiO2) are gaining growing acceptance as an effective wastewater treatment method. A comprehensive review of the UV-TiO2 photocatalytic oxidation process was conducted with an insight into the mechanism involved, catalyst TiO2, irradiation sources, types of reactors, comparison between effective modes of TiO2 application as immobilized on surface or as suspension, and photocatalytic hybrid membrane system. Photocatalytic degradation technique with titanium dioxide is generally applied for treating wastewater containing organic contaminants due to its ability to achieve complete mineralization of the organic contaminants under mild conditions such as ambient temperature and ambient pressure. Recently, photocatalysis studies using TiO2 have been gaining attention for the degradation of persistent organic pollutants and other organic chemicals which are known to be endocrine disruptors. Treatment of wastewater in a titanium dioxide- suspended slurry reactor has been widely utilized due to its simplicity and enhanced degradation efficiency. However, this system requires separation of TiO2 from water after the photocatalytic process. The final section of the manuscript focuses on the removal of TiO2 using a membrane hybrid system. A two-stage coagulation and sedimentation process coupled with microfiltration hollow-fibre membrane process was found to achieve complete removal of TiO2, and the recovered TiO2 can be reused for a photocatalytic process after regeneration
Thiruvenkatachari, Ramesh,Ouk Kwon, Tae,Shik Moon, Il Taylor Francis 2005 Separation science and technology Vol.40 No.14
<P>A pilot scale, slurry type photocatalytic reactor, followed by submerged hollow fiber microfiltration (MF) membrane hybrid system was evaluated for simultaneous and complete destruction of toxic organic chemical bisphenol A (BPA) and separation of photocatalyst TiO 2 ; in order to obtain a reusable quality water. With simple modification to the treatment operation, the effect of photocatalytic reaction at modest variations in temperature was examined. Adsorption pretreatment was carried out prior to photocatalysis (UV/TiO 2 ). BPA adsorption ability on TiO 2 was very less (about 15%) at 25°C. However, adsorption pretreatment followed by photocatalytic oxidation (UV/TiO 2 ) at an elevated nearly constant temperature (about 70°C) helped in increasing the BPA degradation efficiency. The effect of ozone introduction into the treatment stream was also analyzed. Applying ozone along with UV/TiO 2 , brought about a synergistic effect on BPA degradation. Within 3 h, entire 10 ppm of BPA and the by‐product organic compounds were completely removed. TiO 2 particle separation performance using hollow fiber membrane was enhanced by adopting a two‐stage coagulation/sedimentation pretreatment. With initial turbidity of 4000 NTU, the turbidity of the final permeate water was well below 0.1 NTU. Almost complete removal of particles was achieved. Some of the main advantages of this hybrid treatment system include, large‐scale treatment, complete and efficient BPA and its organic intermediates degradation, TiO 2 easily separated after treatment and capable for reuse as it is free from chemical coagulant contaminants, reusable quality water is obtained, and the system has the potential for continuous operation with simple process modifications.</P>
Thiruvenkatachari, Ramesh,Manickam, Matheswaran,Ouk Kwon, Tae,Shik Moon, Il,Woo Kim, Jae Taylor Francis 2006 Separation science and technology Vol.41 No.14
<P>This study investigates the effect of operation parameters on the separation of nitric acid‐water mixture using air gap membrane distillation (AGMD). Porous hydrophobic PTFE membrane was used. The performance was evaluated based on the permeate flux and the nitric acid selectivity. Operating parameters such as feed solution temperature, feed concentration, flow rate, and air gap width were varied. Nitric acid selectivity was found to increase with the increase in feed solution temperature, feed concentration, flow rate, and air gap width. Permeate flux increased, when the feed temperature and the flow rate were increased. The effect of recirculation of the feed solution was also studied. With the recirculation mode, at different initial solution volumes, it was observed that the nitric acid concentration in the feed and the permeate, increased. The rate of flux decline was greater, when the initial feed solution volume was lower.</P>
전종익,정흥조,( Ramesh Thiruvenkatachari ),심왕근,문희,이재욱 한국화학공학회 2007 화학공학의이론과응용 Vol.10 No.2
The performance of hybrid process consisting of coagulation and membrane treatment was evaluated for secondary domestic wastewater reuse. The determined optimal coagulation condition was 0.75 g l-1 coagulant dose and pH 6. The objective of this hybrid process was to identify the optimum method of combining coagulation with microfiltration membrane system. The process of combination of coagulation treatment with membrane, involves two different methods. Firstly, coagulation was introduced as a pretreatment for membrane operation. Secondly, coagulation was integrated with membrane treatment as a in-line process. The performances were compared in terms of flux decline and removal efficiency. Result showed that the former was more efficient as well as essential for the prevention of flux decline than the latter. The removal efficiency was about 70%. It was found that coagulation-membrane hybrid process was suitable for secondary domestic wastewater reuse.