AWWA WQTC64147

A new concept for drinking water treatment is investigated on pilot scale. The treatment processconsists of fluidized ion exchange (FIEX) to remove multivalent positive ions like calcium,ultrafiltration (UF) for removing suspended solids and pathogens, nanofiltration (NF) for removingpathogens, trace organic contaminants and to increase biological stability, marbel filtration tocondition the water and granular activated carbon (GAC) filtration to remove apolar tracecontaminants. The pilot research is aiming at membrane fouling prevention in both ultrafiltration aswell as nanofiltration. Also the effectiveness of the combination nanofiltration and GAC with respectto the removal of trace organic substances is investigated. The UF-experiment was conducted withoutinline coagulation at constant flux (65l/h.m2) for 14 days. The results showed that during dose 14 daysUF performance is stable if the FIEX-effluent is used as the feed and NaOH was used in the enhancedbackwash. Because of the absence of multivalent positive ions there was no scaling in the NF, even athigh recovery (97%). NF-scaling was investigated at various recoveries with constant recycle flowvelocity (0.12 m/s). For the effectiveness of the whole process, different pharmaceuticals andpesticides are dosed in front of NF and measured in the effluent of both the nanofiltration as well asthe GAC. The micropollutants were efficiently removed by the combination NF/GAC because ofthe absence of pre-loading on the GAC. The polar substances (eg. MTBE) with molecule weightsmaller than 100 daltons were not retained by the treatment process. The concept is promising toproduce high quality drinking water, and the cost (50 euro cents per cubic meter) is competitive withconventional treatment concepts. Includes 10 references, tables, figures.



Keywords: Nanofiltration; Organics; Ultrafiltration; Pathogens; Ion Exchange; Granular Activated Carbon; Fouling; Calcium