Technologies for Boron Removal

Abstract

Boron has been widely used in various manufacturing industries, and the level of boron in the industrial effluent can range from as high as several grams per liter to as low as a few micrograms per liter. Due to the potential adverse health effect of boron on human beings, the World Health Organization (WHO) has provided a guideline for the boron concentration in drinking water to be less than 0.5 mg/L. Therefore, the boron-containing effluents or solutions should be treated before they could be discharged into natural water bodies. This paper critically reviews various technologies used for boron removal, including those recently developed, electrocoagulation (EC) and double-layered hydroxide (DLH) compounds, as well as conventional and advanced treatment technologies such as chemical precipitation, ion exchange, reverse osmosis, adsorption, liquid−liquid extraction, and electrodialysis. Particular focus is given to the comparative performance and advantages and disadvantages of these technologies for boron removal. EC and DLH have been proven to be highly effective for boron removal from solutions with a high boron concentration, while a DLH compound alone can effectively treat solutions with low boron concentrations (<50 mg/L) to the WHO recommended drinking water standard (≤0.5 mg/L). Pilot- and full-scale trials, however, need to be carried out in order to implement EC and DLH compounds for removing boron in a full scale.