Hebei University of Environmental Engineering, Qinhuangdao, Hebei 066102, China E-mail:
Yingkou Institute of Technology, Yingkou, Liaoning 115000, China.
Water Sci Technol. 2020 Mar;81(6):1130-1136. doi: 10.2166/wst.2020.208.
Heavy metal pollution has become one of the most serious environmental problems today. The preparation of magnesium hydroxy carbonate from low-grade magnesite, and the chemical precipitation of heavy metal wastewater with magnesium hydroxy carbonate as precipitating agent were undertaken. The removal efficiencies of heavy metals were improved by increasing the dose of magnesium hydroxy carbonate, and the applicable dose of magnesium hydroxy carbonate was 0.30 g for 50 mL of the wastewater (6,000 mg/L). The precipitation reactions proceeded thoroughly within 20 min. At this time, the removal efficiencies of heavy metals were above 99.9%. The final pH value was 7.1, the residual VO , Cr and Fe concentrations were 0.01, 0.05 and 1.12 mg/L, respectively, which conformed to the limit of discharge set by China (0.5-2.0 mg/L, GB 8978-1996). The precipitate was mainly composed of FeO, VO and CrO, which can be recycled as secondary raw material for metallurgical industry. The treatment of the heavy metal wastewater with magnesium hydroxy carbonate was successful in decreasing the concentrations of VO , Cr and Fe in wastewater.
重金属污染已成为当今最严重的环境问题之一。本研究采用菱镁矿为原料制备碱式碳酸镁，并以其作为沉淀剂对重金属废水进行化学沉淀处理。通过增加碱式碳酸镁的用量，可以提高重金属的去除效率，当 50mL 废水中（6000mg/L）的镁羟碳酸盐用量为 0.30g 时，去除效果最好。沉淀反应在 20min 内即可完全进行，此时重金属的去除率均在 99.9%以上。最终 pH 值为 7.1，残余的 VO、Cr 和 Fe 浓度分别为 0.01、0.05 和 1.12mg/L，均符合中国（0.5-2.0mg/L，GB 8978-1996）的排放标准。沉淀产物主要由 FeO、VO 和 CrO 组成，可作为冶金行业的二次原料回收利用。碱式碳酸镁处理重金属废水可有效降低废水中的 VO、Cr 和 Fe 浓度。
