Water Contamination – Boron Removal with SWRO.
As the scarcity of fresh drinking water becomes a growing concern worldwide, new technologies involving seawater reverse osmosis (SWRO) systems, specifically innovation around their reverse osmosis membranes, are in focus with their ability to offer a solution. Although SWRO systems are already effective at removing over 99% of total dissolved solids (TDS) there has been growing concern in many locations over the effectiveness of removing one toxic element in particular: boron. With new guidelines for boron contamination levels in drinking water, traditional reverse osmosis membranes haven’t been a viable solution to this problem. New developments in SWRO membranes have been shown to increase the effectiveness raising it from 91% to 98% boron removal. In combination with a post-treatment process, SWRO has shown to be a cost effective way to reduce the boron and other TDS to acceptable levels for drinking water worldwide.
Boron is an element that is contained in a healthy body at a level of approximately 0.7 ppm. It is not considered an essential mineral for bodily functions but it is absorbed through consumption of plants or fluids. For the average person their daily intake is about 2 mg, which is well below toxic rates of 5g per day; where negative health effects begin. Amounts exceeding 20g per day are considered to be the fatal toxicity limit. Both the World Health Organization (WHO) and the European Union (EU) have set standards for Boron in drinking water at 0.5 mg/L and 1 mg/L respectively.
The boron contamination that is currently observed in seawater varies from about 4 to 5.5 mg/l, which is about ten times greater than the standards set by the WHO. Most of this toxicity can be attributed to agricultural fertilizers and coastal cities water treatment plants discharge; it is commonly added to soap and detergents. For years, most reverse osmosis membranes have only been able to reject 73-90% of the boron contamination, but with recent advancement from manufacturers, including Hydranautics, the newer high boron removal reverse osmosis membranes can achieve a 94-98% rejection rate. Coupled with this advancement in new membrane technology there has also been research that analyzed the various pre and post-treatment options to optimize the efficiency and cost effectiveness of the SWRO process.
To make the SWRO process most cost effective and still meet all of the boron contamination guidelines there are a few different methods that have been tested and implemented with great success. If the initial salt water is beyond the capabilities of the new reverse osmosis membranes, then a combinatory process of mixing brackish water reverse osmosis (BWRO) that is treated to increase the pH to a 10-11 level of alkalinity with the initial salt water is required to achieve the desired boron rejection rate. By mixing this alkaline-BWRO and high boron removal reverse osmosis membranes people can meet the boron contamination guidelines and remain cost effective. Often this is not necessary as the new high boron SWRO membranes, made by Hydranautics, can effectively remove enough boron contamination on its own, as long as the initial water conditions are within an acceptable range.
These advancements in reverse osmosis membranes, especially related to removing boron contamination by SWRO, have afforded many companies and municipalities access to affordable clean drinking water. As more people need access to clean pure water for personal consumption and industrial use the advancements made by Hydranautics, and other reverse osmosis membrane manufacturers, will allow the SWRO process to become an option for even more municipal water treatment facilities.