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With the promulgation of more stringent regulations to guarantee that drinking water presents minimal health risks, nanofiltration (NF) and lowpressure reverse osmosis membrane (RO) processes are nowadays considered forsurface water treatment. However, NF and RO spiral wound membranes are sensitiveto fouling and an advanced pretreatment such as conventional train,microfiltration (MF) and ultrafiltration (UF) may be necessary to controlproductivity. Consequently, a study was undertaken to evaluate the efficiency ofthe combined processes, know as Integrated Membrane Systems, for surface watertreatment. Two IMS were evaluated on polluted low salinity water: UF andconventional train prior low fouling reverse-osmosis membranes (LFRO). The oneyear study has revealed the efficiency of the IMSs for surface treatment. BothIMSs tested produced water quality that exceeded the most stringent water qualityproposed in the new European Directives. However, in the case of blending withthe pretreated water for re-mineralization, clarified water has to be disinfecteddue to its low microorganism removal. In terms of RO hydraulic performances, UFpretreatment was found to be more effective to control RO fouling. Despite thefact that UF reduces the SDI well below the maximum advised by the membranemanufacturer, slight fouling occurred on the RO membranes at high flux. Organicmaterial plays a role in membrane fouling and therefore reducing SDI may notguarantee a low fouling rate of the RO membranes. Preliminary cost estimationindicated a water cost below 0.3 US$/m3 produced considering an IMS composed ofsludge blanket clarifier, UF and RO (bypasss of 50%). This cost is in a range ofconventional treatment train designed to achieve similar water quality (totaldissolved solids, organic matter, micropollutants, disinfection). Includes 8 references, tables, figures.

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Edition: Vol. - No. Published: 05/01/2001 Number of Pages: 16File Size: 1 file , 470 KB