高濃度鉄・マンガン含有地下水の連続膜ろ過および薬品洗浄特性

抄録

The groundwater which contained iron, manganese and disolved silica in high concentrations, was oxidized to be deposited under the presence of manganese dioxide. It was filtered through two types of UF membranes and an MF membrane at a membrane filtration flux of 1-3m/d. The change of transmembrane pressure difference and the quality of the filtrate were investigated. After the continuous filtration experiment, the chemical cleaning effect was investigated. It is considered that the slower membrane filtration flux gives larger quantity of filtrate. When the membrane filtration flux decreases to a certain level, the effect of the membrane filtration flux becomes insignificant. The UF membrane having a smaller moleculer weight cutoff will suppress the increase of transmembrane pressure difference after a long period of operation. If the detention time is 30 minutes or more, the concentration of manganese dioxide becomes a factor rather than the detention time of the reaction tank. In chemical cleaning, the flux of UF membrane is almost perfectly recovered by acid cleaning, but the flux of MF membrane shows a poor recovery. A presumable cause of MF membrane is the direct invasion of manganese beneath the membrane.