Study on performance of ultrafiltration membrane-based pretreatment for application to seawater reverse osmosis desalination

摘要

The objective of the work was to study at lab-scale the efficiency of hybrid process- couplingnpowdered activated carbon (PAC) adsorption or FeCl3 coagulation and UF- for marine organicnmatter removal. Regenerated cellulose membrane with 30 kDa and actual seawater fromnMediterranean Sea were used. The coagulant was FeCl3 and adsorbents were two PAC types,nwith different surface area and pore size distribution. The results showed that PAC adsorption/UFnperformed higher efficiency in terms of organic removal than FeCl3 coagulation/UF. Organicnmatter removal up to 50% was obtained for a PAC dose of 200mg/L. According to highnperformance size exclusion chromatography (HP-SEC) analysis, the organics removed bynPAC/UF are approximately 10 kDa. Therefore, the effect of PAC adsorption was deeply evaluatednin terms of UF membrane fouling rate. The fouling rate was reduced when increasing PAC dosenfor both PAC types, in particular when PAC with a higher BET surface area and larger fractionnof micropores was used. On the other hand, the results showed that UF unit could highlynreduce SDI3 from 26 to 9. The addition of PAC and FeCl3 to UF allowed a further reductionnof SDI3 from 9 to 4–6.