化学沉淀法处理离子交换含盐废水试验

Experiments of Ion Exchange Saliferous Wastewater Treatment by Chemical Precipitation

在原有的离子交换系统中增加一个回收系统,分步沉淀处理后去除废水中大部分的钙镁离子,清液作为再生剂回用的同时得到钙盐镁盐2种副产品,低含盐废水可静置澄清后回用作清水,试验了各种工艺条件的影响。结果表明,以NaOH为主剂的沉淀剂A进行第1步沉淀,沉淀分离后再投加以Na2CO3为主剂的沉淀剂B进行第2步沉淀,对硬度离子的去除效果更好;使用回用的再生剂处理树脂后生产的软化水在一定时间内没有检测出硬度离子;所得CaCO3的质量分数为97.2%纯度较高,可作为化工原料出售;浓盐废水作为再生剂回用前先要补充氯化钠,并用盐酸中和处理。

A recovery system was added in the original ion exchange system could remove most of the calcium and magnesium ion in wastewater by fractional precipitation treatment.Clear liquid could reuse as regenerant and at the same time get two by-products such as calcium salt and magnesium salt,low salt wastewater could be reused as clear water by standing and clarification,tested different influence of the process conditions.The results indicated that the hardness ion removal effect was better when adopted sodium hydroxide as main reagents of the precipitating agent A in step 1 precipitation,after precipitation separation added sodium carbonate as main reagents of the precipitating agent B in step 2 precipitation;Softened water produced by reused regeneration agent used in resin treatment did not detect the hardness ions in a certain time;The mass fraction of calcium carbonate was 97.2% which was high,and could be sold as chemical raw materials;Sodium chloride supplied to concentrated salt wastewater before its reuse as regeneration agent,and used hydrochloric acid for neutralization processing.