Although reverse osmosis (RO) filtration is designed to reject 99% of colloids, organic deposits, bacteria and viruses, there is still a chance that low concentration of organics, as low as parts per trillion (ppt), will be able to pass through the membranes [Chin, 1996]. For example, ultrapure water is found to contain trace amounts of impurities such as organics, colloids and microorganisms and therefore needs further treatment [Matsuda et al., 1996].