Taro Urase's Laboratory

Membrane related researches of Urase Labo

1. Current research topics

The growing numbers of the applications of membrane technology can be found in wastewater treatment. We are investigating the enhanced removal of micropollutants which cannot be treated in conventional activated sludge process, by using membrane bioreactors (MBRs). We are also investigating the application of of membrane technology to the treatment of various types of industrial wastewater, which may contain dye effluent and may have an extream pH and a high temperature. Following publications are parts of our activities in this field.

(1) K. O. Agenson, T. Urase (2007): Change in membrane performance due to organic fouling in nanofiltration (NF)/reverse osmosis (RO) applications, Separation and Purification Technology 55 (2), 147-156.
(2) Thridpong Srisukphum, Chart Chiemchaisri, Taro Urase, Kazuo Yamamoto (2009): Experimentation and modeling of foulant interaction and reverse osmosis membrane fouling during textile wastewater reclamation, Separation and Purification Technology, 68, 37-49.
(3) T. Srisukphun, C. Chiemchaisri, T. Urase, K. Yamamoto (2010): Foulant interaction and RO productivity in textile wastewater reclamation plant, Desalination 250, 845-849.
(4) Ahmad SHAHATA, Takumi OMATA, Taro URASE (2013): Removal of color from molasses wastewater using membrane bioreactor with acidic condition, Journal of Water and Environment Technology, Vol. 11, No.6, 539-546.
(5) Ahmad Shahata, Taro Urase (2016) Treatment of Saline Wastewater by Thermophilic Membrane Bioreactor, J. of Water and Environment Technology, Vol. 14, No. 2, pp. 76-81. DOI: 10.2965/jwet.15-044

2. Summary of studies before 2005

2.1 Rejection characteristics of nanofiltration membranes

The rejection characteristics of nanofiltration, low pressure reverse osmosis, is investigated. The experimental results are analyzed by the extended Nernst Plank equation, which is usually used for the explanation of solute rejection in electrically charged membranes. The reason for lower rejection of nitrate compared to that of chloride is explained by considering the difference in affinity of the solutes to the membrane materials. The rejection of metals such as arsenic compounds are also studied with different pH. The application of nanofiltration and/or reverse osmosis to landfill leachate treatment is also studied.

(1) C. Ratanatamskul, K. Yamamoto, T. Urase, S. Ohgaki (1996): Effect of operating conditions on rejection of anionic pollutants in the water environment by nanofiltration especially in very low pressure range, Wat. Sci. & Tech., 34, 9, 149-156.
(2) T. Urase, M. Salequzzaman, S. Kobayashi, T. Matsuo, K. Yamamoto, N. Suzuki (1997): Effect of high concentration of organic and inorganic matters in landfill leachate on the treatment of heavy metals in very low concentration level, Wat. Sci. & Technol., 36, 12, 349-356.
(3) C. Ratanatamskul, T. Urase, K. Yamamoto (1998): Prediction of behavior in rejection of pollutants in ultra low pressure nanofiltration, Wat. Sci. & Technol., 38, 4/5.
(4) T. Urase, Jeong-ik Oh, Kazuo Yamamoto(1998): Effect of pH on rejection of different species of arsenic by nanofiltration, Desalination, 117, 11-18.
(5) J.I. Oh, T. Urase, H.Kitawaki, M.M.Rahman, M.H.Rhahman, K. Yamamoto(2000): Modeling of arsenic rejection considering affinity and steric hindrance effect in nanofiltration membranes, Wat. Sci. & Technol., 42, 3-4, 173-180.
(6)M. Thanuttamavong, J.I. Oh, K. Yamamoto and T. Urase (2001): Comparison between rejection characteristics of natural organic matter and inorganic salts in ultra low pressure nanofiltration for drinking water production, Water Science and Technology - Water Supply, 1, 5-6, 77-90.

Click here for Papers presented at International conference on Membranes in drinking and industrial water production, 2002, Mulheim, Germany

Click here for Papers presented at International Membrane Science and Technology conference, 2003, Sydney, Australia

Click here for a paper presented at International conference on Wastewater reclamation and reuse for sustainability, 2005, Jeju, Korea

2.2 Membrane Bioreactor (MBR)

A wastewater treatment system by activated sludge combined with the membrane separation process is developed for the on-site treatment of domestic wastewater. Effect of temperature on removal of nitrogen is also investigated. After 2003, the use of MBR for the removal of micropollutants is investigated.

(1) C.Chiemchaisri, Wong Yien Kiat, T.Urase, K.Yamamoto (1992): Organic stabilization and nitrogen removal in membrane separation bioreactor for domestic wastewater treatment, Wat. Sci. & Tech., 25, 10, 231-240.

Click here for Papers presented at International Membrane Science and Technology conference, 2003, Sydney, Australia

Click here for a paper presented at International conference on Membranes in drinking and industrial water production, 2004, L'Aquila, Italy

2.3 Removal of microbial particles in membrane processes

The characteristics of removal of microbial particles in membrane processes are investigated. We have found that ultrafiltration membranes and nanofiltration membranes are not the complete barrier against viruses though the nominal cutoff size of these membranes are smaller than the size of viruses. The typical rejection range of viruses by ultrafiltration membranes and nanofiltration membranes is around 99.99%. The reason for the virus leakage is that thin skin type membranes have abnormally larger pores in small number which explains virus leakage. Microfiltration membranes give rather steady rejection based on pore size than untrafiltration membranes and reverse osmosis membranes. The pore models for prediction of microbial rejection is also studied. The factors affecting rejection of microbial particles such as solution pH are also investigated.

(1) T.Urase, K.Yamamoto, S.Ohgaki (1994): Evaluation of virus removal in membrane separation process by using coliphage Q-beta, Wat. Sci. & Tech., 28, 7, pp9-15.
(2) T.Urase, K.Yamamoto, S.Ohgaki (1994): Effect of pore size distribution of ultrafiltration membranes on virus rejection in crossflow condition, Wat. Sci. & Tech., 30, 9, 199-208.
(3) T.Urase, K.Yamamoto, S.Ohgaki, N. Kamiko (1994): Rejection characteristics of viruses by ultrafiltration membranes and nanofiltration membranes, Environmental engineering research, 31, 171-180(in Japanese).
(4) T. Urase, K. Yamamoto, S. Ohgaki(1996): Effect of pore structure of membranes and module configuration on virus retention, J. of Membr. Sci., 115, 21-29.
(5) G. Herath, K. Yamamoto, T. Urase (1998): Mechanism of bacterial and viral transport through microfiltration membranes, Wat. Sci. & Technol., 38, 4/5, 489-496.
(6) G. Herath, K. Yamamoto, T. Urase (1999): Removal of viruses by microfiltration membranes at different solution environments, Wat. Sci. & Technol., 40, 4-5, 331-338.

2.4 Fouling mechanism of membranes in membrane separation bioreactors

The increase in volume flux and prevention of decrease in volume flux during long term operation is very important in environmental applications of membrane separation processes. The mechanism of particle accumulation, constituents in filtration resistances, and formation of gel-layers on membrane surface were considered. The promoted back diffusion of protein particles was examined by using viral particles as a model. Theoretical explanation has been made.

(1) T. Urase, K. Yamamoto (1991): Factors affecting crossflow microfiltration in wastewater treatment, proc. of Environ. Sani. Eng. Research, 27, 55-64 (in Japanese).
(2) G. Herath, K. Yamamoto, T. Urase (2000): The effect of suction velocity on concentration polarization in microfiltration membranes under turbulent flow condition, J. of Membrane Science, 169, 175-183.