Application of some combined adsorbents to remove salinity parameters from drainage water

Due to high expenses of energy, desalination of saline waters by low-cost methods is important. To investigate the ability of combinations of five adsorbents (peat, activated carbon, zeolite, anionic resin, and cationic resin) to remove salinity ions from aqueous solutions, ten treatments were prepared for a batch experiment, using saline drainage water with total dissolved solids of 3.24 g L−1. At first, a pre-test was conducted to analyze the behavior of these adsorbents in adsorption of chromium (from an industrial wastewater containing 15.1 mg L−1 Cr(III) and 45.1 mg L−1 Cr(VI)). Then, the same combinations of the adsorbents were used to remove salinity ions from the drainage water. The results showed that except cationic resin + zeolite, other treatments tended to adsorb Cr(III) and Cr(VI) completely. Cationic resin + peat, anionic resin + peat, and cationic resin + activated carbon have satisfactory results in desalination process as compared to anionic resin + cationic resin. Almost in all treatments, adsorption of anions was 2.3 to 2.9 times more than cations. Adsorption rates of Ca, Mg, HCO3 and SO4 by adsorbents was satisfactory as compared to adsorptions of Cr(VI) and Cr(III). This study confirmed that cationic resin had higher ability in desalination of the drainage water as compared to anionic resin, and application of cationic resin with peat was the best choice.

Research highlights
► Peat, activated carbon, zeolite, and resin can remove chromium ions from wastewater.
► These adsorbents could be used for removing salinity ions from drainage water.
► Application of cationic resin with peat was the best choice.
► Adsorption of Ca, Mg, HCO3 and SO4 by these adsorbents was promising, compared to Cr.