Boron removal in seawater RO desalination

In the seawater desalination field, WHO requires the boron concentration in drinking water to be below 0.5 mg/l, and this requirement has affected SWRO process design, because of the difficulty to achieve such low boron concentration. In order to overcome this problem, a new SWRO membrane element, which had higher boron rejecting performance, was developed. This new SWRO membrane element exhibits excellent boron rejection performance of 94-96% with high TDS rejection and high water productivity. This new membrane element could reduce the post-treatment loading, and it could be expected the lower drinking water production cost. In order to evaluate the economical impact of the new membrane, the production cost of various SWRO systems with post-treatment processes, the BWRO at high pH condition and the boron adsorbent resin, were estimated. As a result, the cost reduction of the new SWRO membrane was estimated to up to 20 % compared to the conventional SWRO membranes, and the three-stage system, which consists of the SWRO followed by the BWRO at high pH and the boron adsorbent resin for the BWRO concentrate, showed the most cost effective system.