Abstract:

In order to meet environmental requirements， a steel plant has built dust removal and desulfurization unit. There is by-product dilute sulfuric acid wastewater generated in the desulfurization process， which has a certain acidity and contains various heavy metal ions such as chromium， nickel and cadmium， as well as a certain amount （60-4 700 mg/L） of iron， and exceeds the requirements of relevant standards. When the wastewater is treated by traditional alkali neutralization method， it is difficult to remove the heavy metal ions in the wastewater at one time and cannot meet the standard discharge. The alkaline neutralization+chelation+flocculation precipitation method was proposed， and the removal effect of heavy metal ions was investigated. The experimental results showed that by adjusting pH of the wastewater to 8-10， adding 120 mg/L chelating agent DTC-1 or TMT-1， adding appropriate amount of flocculant PAC+PAM and stirring for 20 minutes， the heavy metal ions in wastewater met the requirements of discharge standard， with the advantages of fast settling speed and easy separation. The optimal removal rate of chromium， nickel and cadmium ions reached 99.97%， 99.95% and 99.32%， respectively.

Key words: acid-containing wastewater, heavy metal ion, neutralization, chelation, flocculation precipitation

摘要：

为达到环保要求，某炼钢厂建设了除尘脱硫装置，而脱硫过程中有稀硫酸副产物产生。该稀硫酸废水具有一定酸度，同时含有铬、镍、镉等多种重金属离子，以及一定量（60~4 700 mg/L）的铁，超出环保标准要求。采用传统的碱中和法对该废水进行处理时，难以一次性去除水中的重金属离子，无法达标排放。提出采用碱中和+螯合+絮凝沉淀法处理稀硫酸废水，并考察了重金属离子的去除效果。实验结果表明，调节废水pH为8~10，投加120 mg/L螯合剂DTC-1或 TMT-1，添加适量絮凝剂PAC+PAM搅拌反应20 min，可使稀硫酸废水中的重金属离子达到排放标准要求，具有沉降速度快、容易分离等优点。该方法对铬、镍、镉离子的最佳去除率可分别达到99.97%、99.95%、99.32%。

关键词: 含酸废水, 重金属离子, 中和, 螯合, 絮凝沉淀

CLC Number: 

• X703