Boron removal from saline water: A comprehensive review

Boron is an essential micronutrient for plants and animals as well as a useful component for numerous industries. It is necessary to produce low boron containing water from RO desalination plants for both human consumption and for agriculture. For plants, a small amount of boron is necessary for their growth and development, but boron becomes toxic if the amount is slightly greater than required. Desalinated seawater from RO plants often contains high boron content and, when used for irrigation, has been proven to be damaging to crops including blackberry, lemon, and grapefruit. Apart from the toxic effects of boron on plants, boron should be removed from RO desalination plants to comply with the current guideline value, 0.5 mg/L, for potable water issued by the World Health Organisation (WHO). Currently there is no simple method to remove boron from saline water. The use of multi-pass reverse osmosis membrane (RO) with pH modification and the use of ion exchange using boron selective resins (BSRs) have both been considered as effective methods for the removal of boron. A hybrid process, Adsorption Membrane Filtration (AMF), has received attention as an emerging technology for boron removal with a high efficiency and low operating costs. The purpose of this review is to give an overview on boron in general and to discuss its toxicity. The problems of boron in the MENA (Middle East and North Africa) region are discussed as well as technologies, current and future, for the removal of boron from seawater. The focus is placed on current RO and ion exchange methodologies using BSRs as well as the future for the AMF method. The fundamentals of each process, the effects of experimental parameters, and findings are discussed.