Membrane distillation of power plant cooling tower blowdown water

The objective of this study was to examine the recovery of the power plant cooling tower blowdown water (CTBD) by membrane distillation. The experiments were carried out using a flat plate poly vinylidene fluoride (PVDF) membrane with a pore diameter of 0.22 um by a direct contact membrane distillation unit (DCMD). The effects of operating parameters such as transmembrane temperature difference (delta-T), circulation rate and operating time on permeate flux and membrane fouling have been investigated. The results indicated that permeate flux increased with increasing delta-T and circulation rate. Whereas maximum permeate flux was determined as 47.4 L/m2.h at delta-T of 50 degree Celcius for all short term experiments, minimum permeate flux was determined as 7.7 L/m2.h at delta-T of 20 degree Celcius. While 40 degree Celcius was determined as the optimum delta-T in long term experiments. Inorganic and non-volatile substances caused fouling in the membranes.