Adsorption/co-precipitation—reverse osmosis system for boron removal

Based on research of boron removal from the postindustrial Tarnowskie Gory landfill leachate, containing up to 80 mg B/L, an adsorption/co-precipitation—reverse osmosis (RO) system for boron removal from high boron-containing waters is proposed. The multi-stage RO subsystem operates at high feed-water pH levels to obtain permeates that meet the requirements for wastewater being released to the environment (<1 mg of B/L). The RO retentate containing ca. 300 mg of B/L is being used as the feed-water for the adsorption/co-precipitation step. The supernatant from the above step, containing ca. 95 mg of B/L, is then recycled to the RO step. When analyzing the metal hydroxide type and feed-water boron content influence on the boron adsorption/coprecipitation efficiency, it was found that nickel, aluminum and iron hydroxides are the most efficient and thus, suitable for boron removal. It was also shown that the adsorption/co-precipitation step should be operated at a relatively high boron content in order to avoid a large precipitant load, which causes high RO feed-water salinity.