硫化钠、氯化铝在含镉废水稳定化处理中的对比研究

Stabilization Effect of Sodium Sulfide and Aluminum Chloride toward Cadmium in Wastewater Treatment

以含镉冶炼废渣浸出液模拟渣场淋浸废水,研究了用不同沉淀剂处理低浓度重金属冶炼废水时在效果和机制上的区别。研究了应用硫化沉淀法和氯化铝絮凝法时的投药量、pH值、温度和反应时间对废水中镉、锌离子沉淀效果的影响规律。结果表明:以硫化钠作为沉淀剂时沉淀反应速度较快,影响镉、锌除去率的主要因素是投药量,pH值、温度和反应时间对其的影响很小;实验条件下的适宜工艺参数为:投药量2g·L^(-1)、pH值8、温度35℃、反应时间18min,镉、锌除去率分别可达98.7%和98.1%。以氯化铝为絮凝剂时由于存在絮凝和水解作用,投药量、pH值、温度、反应时间等因素对沉淀效果的影响均较大,pH值是主要的影响因素;其较优化工艺条件为:投药量2g·L^(-1)、pH值9、温度30℃、反应时间50min,镉、锌除去率为90.8%和88.8%。对大水量低浓度含重金属冶炼废水进行稳定化处理时,药剂加投量和环境pH值是应该重点关注的因素;硫化沉淀法在操作条件和沉淀效果方面比氯化铝絮凝法具有一定的优势。

A wastewater treatment using sodium sulfide and aluminum chloride as stabilizer toward cadmium containing smelting slag leachate was introduced,and detail mechanism study was conducted by the way of varying experiment conditions of reagents dosage,p H,temperature and reaction time. The experimental result showed that the precipitation rate was faster when the sodium sulfide was used as stabilizer,and the main factor that controlled the cadmium and zinc removal rate was the reagent dosage,while the p H value,temperature,reaction time showed little influence. The optimal experimental conditions were reagents dosage of 2 g·L^- 1,p H = 8,temperature of 35 ℃ as well as reaction time of 18 min,and the final cadmium and zinc removal rates could be up to 98. 7% and 98. 1%;the precipitation experiment with aluminum chloride as stabilizer was deeply influenced by reagents dosage,p H,temperature,reaction time and the main factor was p H value,which was believed to be the consequential effect of the flocculation and hydrolysis of aluminum chloride. The optimal conditions were reagents dosage of 2 g·L^- 1,p H = 9,temperature of 30 ℃,reaction time of 50 min,and the final cadmium and zinc removal rate were up to 90. 8% and 88. 8%. The precipitation effect of sulfide precipitation was superior to that of aluminum chloride flocculation method when the stabilization treatment was taken toward large flow wastewater with low metal content,and the p H value and reagents dosage should be well considered in the cadmium precipitate operation.