Concentration and treatment of ceric ammonium nitrate wastewater by integrated electrodialysis-vacuum membrane distillation process

Ceric ammonium nitrate manufacture generated a large number of acidic wastewater, which contained a certain amount of ceric. To treatment this wastewater and recovery the ceric resource and waste acid, an electrodialysis-vacuum membrane distillation (ED-VMD) hybrid system was introduced. To establish a stable and efficient system, a series of membrane materials, performance parameters and solution properties were investigated. It was found that NO3- could be separated from Ce4+ and recovered efficiently in ED system. pH value of Cerium wastewater decreased in the ED process which ensured a stable and reliable operation of the following concentration technology. The high resistance of Ce4+ and high NO3- recovery efficiency in ED anode compartment supplied an opportunity for industry waste acid recycling as well. The VMD process provided more than 99.9% rejection of Ce4+ and concentrated it maximally. Furthermore, membrane cleaning procedures were discussed in order to keep the high efficiency of VMD system. The results implied that vapor condensation inside the pores was the main reason caused membrane fouling and flux decreasing. And the drying procedure was the most efficient cleaning method. This work provided a potential treatment process for rare earth metals wastewater treatment, which decreased the wastewater discharge and recycled the resource in some field.