Study on fouling materials in the membrane treatment process for potable water

Abstract

Studies were made on a water treatment process which used hollow fiber microfiltration membranes for potable water. The influent, which was from a eutrophic lake named Kasumigaura, was provided directly into the treatment system, and no pre-treatment such as coagulation was done. Dead-end filtration was carried out under constant rate permeation, and membranes were washed by air-scrubbing. The trans-membrane pressure (TMP) had increased to 100 kPa, and the color of the membranes turned brown after 19 days of operation. X-ray microanalyzer (XMA) revealed that the brown material on the membrane surface was manganese. Furthermore, the amount of total organic carbon (TOC) and manganese in the fouling materials were one order of magnitude higher than that of other inorganic elements. TOC and manganese were dominant fouling materials. By correlating the amount of extracted fouling materials and the recovery of membrane permeability, it was concluded that the decline in membrane permeability was mainly caused by organic matter.