化学法处理电镀混合废水技术条件的研究

Study on Technical Conditions of Chemical Treatment of Plating Mixed Waste Water

本文对化学法处理电镀废水时经常遇到的两个重要问题进行了研究。一、是几种主要的重金属离子沉淀到排放标准时的pH值。通过多次试验得出了一个计算公式:pH=14+1g(Ksp/[M])^(1/n)。按该式可计算出某离子沉淀达标时的pH值。二、是各种络合剂对处理结果的影响。共试验了表面活性剂、氰根、酒石酸钾钠、柠檬酸钠、焦磷酸根、氯化铵、氨三乙酸及多种络合剂共存等八种情况。试验结果表明,表面活性剂对处理结果影响不大,大多数络合剂只有含量高达几百毫克/升时,才对结果有影响,但氨三乙酸的含量仅25mg/L时,镉和铜便不能处理达标了。多种络合剂混合共存也常使Cd、Cu、Ni、Zn等重金属离子的处理结果超过排放标准,也就是说比单一络合剂的废水困难得多。

Two important problems of ten encountered in chemical treatment of palating wastewater have been studied. The first one is the precipitating pH values of several main heavy metal ions, at which they can be precipitated to such an extent that their remains concentratiion can go down to pollution control standards. Through a series of tests, a calculation formala is concluded as follows: pH=14+1g [Ksp/(M)]^(1/n), by which the precipitating pH value required for any metation to go down to the standard can be calculated. The second is the effects on treating results by complexing agents. Eight conditions, such as surfactant, cyanide, potassium sodium tartrate, sodium citrate, pyropbosphate, ammonium chloride or aminotriacetic acid contained individually and various coexisted complexing agents are tested. The results show: (1) the effect of surfactant is not significant; (2) most complexing agents affect the treatment results only when their concentrations reach several hundreds of mg/L, but if the concentration of aminotriacetic is 25mg/ L, Cd and Cu will not go down to the pollution standard; (3) for various mixed and coexisted complexing agents, some heavy metal ions such as Cd, Cu, Ni and Zn would exceed the standard limits even after being treated, i. e. more difficult than those containing a single complexing agent.