Recovery of Cooling Towers Blow-Down Water by Membrane Filtration Methods

Ultrafiltration (UF) are theoretically the best pre-treatment upstream nanofiltration (NF) and reverseosmosis (RO), removing from the feed water most of the potential elements responsible of desalinatingmembranes fouling such as particles, turbidity, bacteria and large molecular weight organic maters. ThisUF membranes reduce also significantly the silt density index below ۳ and often below ۲. Pre-treatmentcould be able to produce proper feed water for NF and RO. The blowdown water of cooling systems onlycontains scale and corrosion inhibitors. This wastewater could be suitable to reuse as makeup water forrecycled cooling water if the particles and colloids stably dispersed in cooling water system have beentreated properly. Otherwise, the particles and colloids dispersed could scale, deposit or block the pipewhen the wastewater from cooling systems being reused/recycled as cooling water without any treatment.Based on water quality requirements and costs of operation, the best choice between UF+NF and UF+ROhybrid process could be proper to blow-down water treatment to reuse.