Application of micellar-enhanced ultrafiltration in the pre-treatment of seawater for boron removal

Abstract

In this research, micellar enhanced ultrafiltration (MEUF) is tested as a seawater pre-treatment before entering RO. The experimental tests were performed by means of monotubular ceramic membranes of 210kDa and 1kDa. Boron is removed from the water flow using sodium dodecyl sulphate as a surfactant. The synthetic solutions contain 5mg/L of boron and SDS concentrations are equal to 1.15g/L and 2.88g/L, under and above the critical micellar concentration, respectively.Experimental data showed that MUEF is efficient in removing boron, with best performances obtained at low pressure, with a low or null surfactant concentration for 1kDa membrane and a high surfactant concentration for 210kDa membrane. Moreover, experimental results have been used to perform a preliminary process analysis for a hypothetic sea-water desalination plant, with MEUF as a pretreatment for the RO section. The results showed that the MEUF guarantees a boron concentration after RO below the allowed threshold, by using a single step osmosis; moreover, in this way it was possible to reduce the energy consumption thus resulting in an appreciable reduction of carbon footprint as well as of the unit cost of water.