Development of a microfilter separation system coupled with a high dose of powdered activated carbon for advanced water treatment

Filtration experiments using a bench-scale immersed membrane separation system combined with PAC (powdered activated carbon) were conducted in order to investigate the effects of PAC on the efficiencies of operation and treatment and to evaluate the performance of the system. The experiments were carried out under such operation conditions as a filtration rate of 1 m/d (or 42 l/m2/h), water temperature of 20-25°C, and PAC dose of 0 g/l (PAC-0), 10 g/l (PAC-10) and 40 g/l (PAC-40). Synthetic secondary wastewater was used as a raw water; the influent concentrations of TOC (total organic carbon), UV254 (UV absorbance at 254 nm) and NH4+-N (ammonia nitrogen) were 9.09 mg/l, 16.4 1/m and 5.0 mg/l, respectively. TOC removal of 51, 74 and 83%, and UV254 removal of 63, 89 and 95% were obtained for PAC-0, PAC-10 and PAC-40, respectively. Ammonia oxidation was observed only for PAC-40, which started to occur on the 20th d from the operation and was completed in 25 d. Average filtration times up to TMP (transmembrane pressure) of 70 kPa were 32, 61 and 97 h for PAC-0, PAC-10 and PAC-40, respectively. The amounts of organic compounds attached to the membrane pore were 380, 280 and 64 mg of TOC per 1 m2 of membrane surface area for PAC-0, PAC-10 and PAC-40, respectively. This study found that the filtrate quality and the performance efficacy were enhanced with the increase in the concentration of PAC introduced into the filtration system.