含铬电镀废水的资源化处理

Resource Recovery of Chromium from Electroplating Wastewater

针对电镀厂产生的高浓度含铬废水,研究了硫化钠还原沉淀法回收电镀废水中的铬的可能性。讨论了pH、投药量、反应时间和搅拌速率等变量对铬回收效果的影响。结果表明:在pH1.6,工业硫化钠(60%)投加量为4.0g/L废水,搅拌速率170r/min和反应时间t=90min的条件下能够将原水中初始浓度为533.1mg/L的三价铬C(rⅢ)和530.0mg/L的六价铬[C(rⅥ)]分别降到42.9mg/L和0.01mg/L。此时铬渣中三氧化二铬(Cr2O3)含量为29.5%,满足回用要求。接下来,为了进一步去除残余的三价铬C(rⅢ),利用正交试验设计讨论了重金属捕集剂(FZ)对其去除的最佳条件。在上述条件下出水中总铬(TCr)浓度最终降到0.94mg/L。

Sodium sulfide - reduction precipitation process was studied for the recovery of chromium from wastewater produced in electroplating plants. The affecting factors such as pH, dosage, reaction time and stirring rate of chromium recovery were discussed. Results showed that under the optimal conditions as pH value 1.6, dosage of sodium sulfide （60%） for industrial use 4.0g/L of wastewater, reaction time 90min and stirring rate 170r/min, the initial concentrations of Cr（ Ⅲ ） and Cr（Ⅵ ） can be decreased from 533.1mg/L and 530.0mg/L to 42.9mg/L and 0.01mg/L respectively. The content of Cr2O3 in chromium slag was 29.5%, satisfactory to the reuse requirement. For removing residual Cr（ Ⅲ ） further with heavy metal chelating agent （FZ）, orthogonal design was discussed and the optimal removal conditions were obtained. The concentration of total chromium in effluent was 0.94mg/L at the end.