Abstract:
The purpose of this research was to study the performance of the prototype of nanofiltration system for municipal drinking water produced based on the influence of membrane type, pressure, percentage of recovery, long-term operation and energy consumption compared with different types of membrane filtration system. The experiment was conducted by using tap water from storage tank at Chulalongkorn University. The prototype system was composed of pre-treatment, membrane filtration and post¬treatment by UV disinfection. There were two processes of experiment compared with the performance between nanofiltration system and reverse osmosis system at the percentage of recovery at 50 and 60. The result shown that nanofiltration system using FILMTEC NF90 and 5 bar-pressure gave flux 0.041 m3/m2 - h which removed >95% of turbidity, >97% of total bacteria, 98% of Ca, 99% of Mg, 50% of Fe, 80% of Zn and 70% of NO. While reverse osmosis system using CMS-RE2540-TE and 10 bar-pressure gave flux 0.045 m3/m2-h which removed >95% of turbidity, >98% of total bacteria, 99% of Ca, >99% of Mg, 50% of Fe, 90% of Zn and 90% of N03. The water derived from both systems met drinking water standard except for pH. Therefore the both system must adjusted pH before being used as drinking water. Since the usage of lower pressure of nanofiltration system, the energy consumption reached 5.67 kw/m3 which was less than reverse osmosis system that consumed 8.73 kw/m3 of energy. As for long-termed operation, it came out that there was no effect with performance of removal. However, it was effect with flux by the more percentage of recovery the faster decrease rate of flux. So the duration of operating was reduced by the decrease of flux of reverse osmosis system which was faster than nanofiltration system when operated at the same percentage of recovery. Another result, Trihalomethane (THMs) removal experiment, shown that both type of membrane using in this research could remove THMs around 10% only.