Boron removal in RO seawater desalination

In the seawater desalination field, the WHO requires that boron concentration in drinking water be below 0.5 mg/l, and this requirement has affected SWRO process design because of the difficulty in achieving such a low boron concentration. In order to overcome this problem, a new SWRO membrane element with 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 post-treatment loading, and it might lower drinking water production costs. In order to evaluate the economic impact of the new membrane, the production cost of various SWRO systems with post-treatment processes, the BWRO at high pH conditions and boron-adsorbent resin were estimated. As a result, the cost reduction of the new SWRO membrane was estimated to be up to 20% compared to conventional SWRO membranes. The three-stage system, which consists of SWRO followed by BWRO at high pH and the boron-adsorbent resin for the BWRO concentrate, was the most cost effective.