锰矿区受污染水体中SO^(2-)_(4)和金属离子的同步去除

Simultaneous Removal of SO^(2-)_(4)and Metal Ions from Polluted Surface Water in Manganese Mining Area

锰矿区地表水中含有大量SO^(2-)_(4)和金属离子,对矿区及周边地区的饮用水安全造成隐患。该研究基于钙矾石沉淀原理采用“两步法”去除高浓度SO^(2-)_(4),并同步降低金属离子浓度及溶液浊度。采用电感耦合等离子体原子发射光谱和离子色谱测定金属离子浓度和SO^(2-)_(4)浓度,并考察了pH、NaAlO_(2)和Ca(OH)_(2)投加量、温度、反应时间等的影响。结果表明:20℃条件下,在pH值7.5~12.5范围内,pH值为12.14时SO^(2-)_(4)的去除率最高,60 min可达55.4%,此时NaAlO_(2)投加量为3.5 mmol/L,Ca(OH)_(2)投加量为7.1 mmol/L。当[AlO^(-)_(2)]<4.0 mmol/L时,SO^(2-)_(4)剩余浓度随NaAlO_(2)投加量增加而下降。当[Ca^(2+)]<13 mmol/L时,增加Ca(OH)_(2)投加量有利于SO^(2-)_(4)去除,但当[Ca^(2+)]>13 mmol/L时,进一步增加Ca(OH)_(2)投加量的作用不大。处理后出水中SO^(2-)_(4)、Ni^(2+)和Mn^(2+)等均满足《地表水环境质量标准》(GB 3838-2002),并协同去除了水中的Ca^(2+)和Mg^(2+)。

Surface water in the manganese mining area contains a lots of SO^(2-)_(4)and metal ions,which cause a potential threat to the safety of drinking water in the mining area and surrounding areas.Based on the principle of ettringite precipitation,a“two-step method”is used to reduce the concentrations of SO^(2-)_(4)and metal ions,and to reduce turbidity.The inductively coupled plasma atomic emission spectrometry and ion chromatography are used to determine the concentrations of metal ions and SO^(2-)_(4),respectively.The effects of initial pH,NaAlO_(2)dosage,Ca(OH)_(2)dosage,temperature and reaction time on the SO^(2-)_(4)removal are investigated.The results show that the SO^(2-)_(4)removal efficiency is up to 55.4%within 60 min at pH 12.14 when the pH varied from 7.5 to 12.5,with a NaAlO_(2)dosage of 3.5 mmol/L and a Ca(OH)_(2)dosage of 7.1 mmol/L at 20 oC.When[AlO^(-)_(2)]<4.0 mmol/L,the residual concentration of SO^(2-)_(4)decreases with the increase of NaAlO_(2)dosage.When[Ca^(2+)]<13 mmol/L,increasing Ca(OH)_(2)dosage is beneficial to SO^(2-)_(4)removal.However,further increasing Ca(OH)_(2)dosage has little effect on SO^(2-)_(4)removal when[Ca^(2+)]>13 mmol/L.The concentrations of SO^(2-)_(4),Ni^(2+)and Mn^(2+)in the effluent all meet the requirements of Environmental Quality Standards for Surface Water(GB 3838-2002),with Ca^(2+)and Mg^(2+)reduction simultaneously.