Comparison of the finished water quality among an integrated membrane process, conventional and other advanced treatment processes

In order to solve taste, odor and hardness problems of finished water from a water works in south Taiwan, a pilot-scale study was conducted. The taste and odor problems were probably cased by the metabolites of algae or other microorganisms as the raw water came from an eutrophicated lake. The conve ntional treatment processes with prechlorination currently employed in the full-scale plant were unable to completely remove them. Three treatment pro cess trains were compared side by side in the pilot testing: a conventional process without prechlorination (Process 1), conventional process plus ozo ne, GAC, and pellet softening (Process 2), and integrated membrane process (UF plus NF) followed by the conventional process. Results show that membra ne process produced water with the best quality measured by turbidity, diss olved organics, biostability or organoleptic parameters. The second best wa s Process 2, which produced water with high biostability and aesthetic qual ity. Even simply avoiding prechlorination could significantly improve the b iostability of the finished water.