IWA Publishing
 IWA Publishing Journals   Subscriptions   Authors   Users   Librarians   FAQs 

Water Supply Vol 3 No 5 pp 303–310 © IWA Publishing 2003

Arsenic removal by MF membrane with chemical sludge adsorption and NF membrane equipped with vibratory shear enhanced process

S.-H. Yi*, S. Ahmed**, Y. Watanabe*** and K. Watari****

*Department of Urban and Environmental Engineering, Hokkaido University, Kita-13 Nishi-8, Kita-ku Sapporo, 060-8628 Japan (E-mail: hyup0601@eng.hokudai.ac.jp)
**Department of Urban and Environmental Engineering, Hokkaido University, Kita-13 Nishi-8, Kita-ku Sapporo, 060-8628 Japan (E-mail: hyup0601@eng.hokudai.ac.jp)
***Department of Urban and Environmental Engineering, Hokkaido University, Kita-13 Nishi-8, Kita-ku Sapporo, 060-8628 Japan (E-mail: hyup0601@eng.hokudai.ac.jp)
****Mitsubishi Rayon Co., Ltd, Higashi-ku Nagoya, 461-8677 Japan


ABSTRACT
Conventional arsenic removal processes have difficulty removing low concentrations of arsenic ion from water. Therefore, it is very hard to comply with stringent low levels of arsenic, such as below 10 g/L. So, we have developed two arsenic removal processes which are able to comply with more stringent arsenic regulations. They are the MF membrane process combined with chemical sludge adsorption and NF membrane process equipped with the vibratory shear enhanced process (VSEP). In this paper, we examine the performance of these new processes for the removal of arsenic ion of a low concentration from water. We found that chemical sludge produced in the conventional rapid sand filtration plants can effectively remove As (V) ions of H2AsO4- and HAsO42- through anion exchange reaction. The removal efficiency of MF membrane process combined with chemical sludge adsorption increased to about 36%, compared to MF membrane alone. The strong shear force on the NF membrane surface produced by vibration on the VSEP causes the concentration polarization layer to thin through increased back transport velocity of particles. So, it can remove even dissolved constituents effectively. Therefore, As (V) ions such as H2AsO4- and HAsO42- can be removed. The concentration of As (V) ions decreased from 50 g/L to below 10 g/L and condensation factor in recirculating water increased up to 7 times by using NF membrane equipped with VSEP.

Full article (PDF Format)


eProduct: Buy this article for £24.00 (IWA MEMBER PRICE: £18.00)
All prices include VAT. For customers where VAT should not be applied, the VAT amount will be removed upon payment