This invention discloses a cost-effective process for separating contaminants and a wide-range of
fouling material from
surface water, ground water and from industrial effluents. Having undergone effective pre-treatment, the water can be purified further by using high-surface area spirally wound micro-
filtration (MF), ultra-
filtration (UF), nano-
filtration (NF) or
reverse osmosis (RO) membranes. High-quality
potable water free from
pathogen and other contaminants is thus produced at low-cost from the pre-treated
surface water and ground-water. Conversely, pre-treated industrial effluents are further purified at a relatively low-cost using NF or RO membranes, thus producing water suitable for recycle or
surface discharge. The process of this invention uses cationic inorganic and / or polymeric flocculants to coagulate and flocculate the water-borne colloidal matter (e.g. clays, iron hydroxides, naturally occurring matter (NOM's), etc.), followed by filtration using a multi-
media filter, charge
neutralization and reversal and final filtration using a 5-micron
cartridge filter. These pre-treatment steps provides a good quality water having a low
Silt Density Index and a significant negative
zeta potential, thereby ensuring against irreversible chemical
fouling of the spirally-wound membranes.