改善明胶生产废水污染的磷酸氢钙回收工艺

A Modified Clean Production Technique of Recovering Calcium Phosphate for Gelatin Plant

在考察明胶生产工艺、废水水质特性的基础上 ,提出一改进的磷酸氢钙清洁回收工艺。在浸灰工段后设一沉淀池 ,沉淀分离石灰沉渣 ,将上层饱和的氢氧化钙浸灰废液送至浸酸工序 ,处理浸酸废液 ,调pH至 4 .7左右 ,回收磷酸氢钙。而原工艺是用灰乳处理浸酸废液回收磷酸氢钙 ,大量饱和Ca(OH) 2 浸灰废液外排 ,造成了难于治理的明胶生产废水高碱、高钙、高悬浮有机物污染。实验证明 ,该改进工艺能消耗大量的浸灰废液 ,有效降低明胶生产废水的高碱特性 ,对悬浮COD的去除效果与使用普通净水剂效果相当 ,且对磷钙复合肥的收率无重大影响 ,所排废液不再是饱和的氢氧化钙溶液 ,钙污染也得到一定控制 ,与原废水相比生化处理难度大大降低 。

A clean production technique, which can reduce wastewater pollution for gelatin plant in pH, suspended COD and Ca 2+ , has been proposed. Precipitated the lime from lime wastewater produced by lime process, then this alkali water without lime is added to another acidic wastewater produced by pickling process to e CaHPO 4. But in traditional technique, the lime wastewater with lime is added to pickling wastewater directly, little lime wastewater was consumed and large amount of lime wastewater, which contains high pH, high-suspended COD and high Ca, and is difficult to treat by biological treatment, is produced for gelatin plant. It is proved by the experiment that the final wastewater produced by the clean production technique has lower pH for the pickling wastewater consuming large amount of lime wastewater. It has lower COD for all the suspended COD and partial soluble COD being separated from the wastewater absorbed by CaHPO4 sedimentation, and that it has lower Ca for it is no longer the saturated lime solution.