Pilot-plant study of a high recovery membrane filtration process for drinking water treatment

Successful application of energy efficient dead-end micro-filtration (MF), which does not require recirculation like cross-flow filtration, depends on achieving high recovery rates. In this study, two different types of pilot scale membrane systems (horizontally and vertically stretched membrane filters) were evaluated based on the effects of pre-chlorination, intermittent chlorination and circulation flow by air-scrubbing. Additionally, the effects of operating factors including physical cleaning and chemical cleaning on membrane fouling were examined. The vertically stretched membranes showed better performance than horizontally stretched membranes at filtration fluxes of either 0.55 m/day or 0.78 m/day even under 2.6 to 27.5°C and raw water turbidity higher than 300 units, as long as intermittent chlorination (10 mg/l once a week) along with the circulation flow by air-scrubbing (once in 30 minutes) in the housing were employed. It was demonstrated that the vertically stretched membranes have been operated for one year without chemical cleaning of the membranes, wherein the recovery of raw water as a filtrate was 97.0% or 98.9%.