A combined hydrate-based method for removing heavy metals from simulated wastewater with high concentrations

Abstract With the acceleration of industrialization, heavy metal pollution has significantly threatened environmental and human health. An innovative hydrate-based method was proposed in this study to treat wastewater containing heavy metal ions with high concentrations. The feasibility of this technology was confirmed by measuring ion concentration in purified water through hydrate dissociation. By forming R141b hydrate in simulated heavy metal solution under atmospheric pressure at 2 °C, the treatment effect on the wastewater was examined in terms of removal efficiency, water yield, and enrichment factor. Experiments explored how these treatment characters were influenced by changing the volume of hydrate former, post-treatment method, concentration, and species of ions. Considering the treatment effect and economy of the technology, we selected the optimal volume ratio was 4. We combined the solid-liquid separation as the post-treatment method of hydrate-based wastewater treatment and selected vacuum filtration combined with centrifugation as the optimal method, which increased the removal efficiency significantly. The treatment effect was determined by ion concentration, independent of the species of ions. The highest removal efficiency of copper ion reached 91.85%, up to 81.05% yield of water, with an enrichment factor of 2.686. The removal efficiency of different ions in complex wastewater was about 89%. Under the experimental conditions of this research, the limit value of copper ion concentration in the wastewater treated with the hydrate method reached 70 g/L. The wastewater treatment technology proposed in this study using hydrate may promote the development of treating wastewater containing high concentrations of heavy metals.