A BASIC STUDY ON ADSORPTION PROPERTIES OF SOLUTE ON MEMBRANES AND CONTROL OF MEMBRANE FOULING

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Membrane filtration has been used for advanced treatment for wastewater treatment and especially membrane bioreactor has lately attracted attention as a new type advanced treatment process for wastewater. In membrane filtration process a common problem is control of membrane foluing. The objectives of this work were to clarify the adsorption properties of organic solutes on membrane materials and to characterize the fouling meterials on the used membranes for actual wastewater treatment.The adsorption properties were examined with high performance liquid chromatography using membrane materials, i.e.cellulose acetate (CA), alumina, and chlorinated polyethylene (PE), as a stationary phase. Although alumina did not adsorbed alcohols and benzene, organic compounds were adsorbed on CA and PE.In later case logarithm of capacity factor (log k'), which is an index of adsorption amount, were correlated linearly with octanol/water partition coefficient (log K_<o/w>). This indicated that the adso … More rption was controlled by hydrophobic interaction.Halogen as a substituent promoted the adsorption on CA at similar degree in comparison with carbonyl group. The adsorption of amino acids, nucleic base, and nucleotides were strongly influenced by pH.PE was especially adsorbed aromatic compounds and the adsorption amounts based on surface area of the stationary phase were larger at about 100 times than those for octadecil silane (ODS).The fouling materials on the membranes used for domestic wastewater treatment were analyzed by EPMA,XPS,and FTIR.It was observed that the fouling material on membrane surface was easily removed by membrane cleaning, but the results from elemental analysis for the membranes indicated that organic foulant was not removed completely. This and the results of membrane filtration experiment suggested that the removal of fouling material in membrane pore was necessary to recover the water flux. For this purpose the cleaning with sodium hypochlorite solution was effective. Less