Abstract
We propose a new method to measure the fouling potential of feed water in the membrane separation processes.This method is using the plugging coefficient (K) in four kinds of pore blocking filtration models including the cakefiltration model with clear theoretical background as values for water quality evaluation alternative to SDI（SiltDensity Index) which is commonly used to assess the fouling potential in the membrane separation processes. Weexamined the validity of the plugging coefficient as a water quality index through comparison with SDI values. Thefollowing results were obtained. 1) Four kinds of plugging coefficient (Kb,Ki,ksand Kc) were proportional to the con-centration of foulant contained in the samples of different concentration of oolong tea diluted with ultrapure water, 2)Ki,ksand Kcmeasured with the membrane of small pore size (0.2μm) were larger than that of large pore size (0.45μm), and 3) Kiand kswere free from the influence of liquid temperature, while Kb, Kcand SDI were dependent onliquid temperature, 4) Kiand ks were well correlated with SDI15values of samples including the actual raw waterslike sea water, and 5) Kiis recommended as the water quality index because it does not contain the term of initial fluxas compared with ks.
