Towards Zero Liquid Discharge in drinking water production

“Nanofiltration (NF) and reverse osmosis (RO) membranes are used to produce clean water, but also produce a concentrate stream which contains most of the contaminants. Discharging concentrate streams to the environment is hindered by regulations, which are becoming more strict, and by the desire of recovering every single valuable atom. Therefore, the minimization of the concentrate volume to almost zero, is required in order to make treatment of the concentrate feasible. Currently several research studies are being conducted to find smart zero liquid discharge (ZLD) strategies in water desalination. In this PhD work the feasibility of reaching very high recovery (which equals a very low volume of concentrate) in a system consisting of cation exchange pretreatment, NF and RO (with the RO implemented on the NF concentrate to increase feed water recovery) was studied. The outcome of this research indicates that the nearly ZLD concept is technically possible, with the right combination of techniques. The studied system could be applied for the production of drinking water from ground water or surface water with high concentrations of bivalent cations, silica and/or organic micropollutants.”

(Citaat: Salvador, C. – Towards Zero Liquid Discharge in drinking water production)