In situ gelation treatment of desulfurization wastewater using alginate

To overcome the limitations of traditional desulfurization wastewater treatment in coal-fired power plants that entail complicated processes and high chemical consumption, we propose a novel in situ gelation treatment combining flocculation and adsorption using alginate without additional cross-linking agents. Metal ion pollutants in desulfurization wastewater were employed as cross-linkers to gelate biomacromolecules of alginate resulting in the simultaneous formation of hydro-gels and the removal of pollutants. The results show that alginate can effectively utilize the metal ions in desulfurization wastewater, which are instantaneously gelated into hydrogels, resulting in flocculation and adsorption. An alginate dosage of 12 g/L and a reaction time of 3 h were identified as the optimum reaction conditions. Alginate was modified using 1,3,5-triazine-2,4,6-trithiol trisodium salt, ethylenediamine and thiosemicarbazide to enhance its contact with metal ions. The results demonstrate that the optimum treatment effect was obtained using ethylenediamine at 0.02 g/L, with removal rates of 71.1%, 70.8%, 64.1% and 65.0% for Ca, Cr, Cd and As, respectively. The method proposed here is easy to operate and with low cost, suggesting broad prospects for application in industrial wastewater treatment.