Microfiltration productivity and water quality in relation to pretreatment, temperature and flux

Microfiltration was evaluated as a water treatment process using the 60 gpm (3.8 L/s) Memtec pilot plant in Manitowoc, WI, USA. The pilot plant operat ed for over six months. Productivity as measured by mass transfer coefficie nt (MTC) decline and water quality, as measured by turbidity, particles and coliform rejection were evaluated for microfiltration with no pretreatment , microfiltration with alum addition and microfiltration with PAC addition in the pilot plant study. The effects of temperature on microfilter fouling were evaluated by model development and data collection. Alum addition rel ative to PAC addition or conventional pretreatment increased the run-time f rom 10 days to 30 days at 50 gfd (85 L/hm(2)) and 25 degrees C. Turbidity, particle and coliform rejection was independent of pretreatment. Run-time b etween chemical cleanings increased with decreasing flux and increasing tem perature. Log rejection of turbidity and particles increased with increasin g concentration. Infinite log rejection of coliforms was observed for a 1-2 log feed stream concentration.