Removal of ferrous from the wastewater with high-concentration heavy metal by induced crystallization

This work had proposed an effective solution to treat the iron-containing heavy metal wastewater by induced crystallization. In this study, a hydraulic fluidized-bed reactor was employed to remove ferrous from the high-concentration heavy metal wastewater. Sand grains (Fe free) were used as carriers. It was found that the optimum initial pH, molar ratio of [CO₃ ^2–]/[Fe²⁺], HRT and the hydraulic loading were 3.0–3.5, 2.0:1, 40 min and 31 m/h, respectively. Under the optimal condition, Fe²⁺ removal rate reached above 95% when the initial concentration was 100 mg/L. The average particle diameter of the carriers increased from 0.32 mm to 0.48 mm during the continuous operation for 30 days. In addition, crystalline products were observed on the surface of the sand grains and Fe was detected in the products. The study revealed that hydraulic fluidized-bed reactor had great potential on removal from the wastewater containing high-concentration heavy metal.