Combined Inducing Crystallization Process For The Copper-containing Complex Wastewater Treatment

The control of heavy metal pollution is imperative because the heavy metalpollution is becoming serious due to the increasingly discharge of heavy metalwastewater. Induced crystallization is a new technology for heavy metal wastewatertreatment. Fludized bed is often adopted in induced crystallization process; however, thefluidized bed reactor has the disadvantage of higher energy consumption, lowerefficiency and easily blocking as well. In this study, the fixed bed reactor with inducedcrystallization was developed for the heavy metal wastewater treatment. Twopretreatment methods that advanced oxidation and replacement were chosen forbreaking the complex and releasing the free copper ion. Then the copper-containingwasterwater went into the induced crystallization reactor and was removed throughinduced crystallization through the optimization of operation parameters. Moreover, theposttreament of coagulation, precipitation and filtration were adopted to ensure theeffluent quality.The operation results of the two induced crystallization reactors showed that undereach operation condition, the removal rate for copper ion in advection flow reactor andvertical flow reactor were43.8%and86.5%respectively, and copper treatmentperformance of the vertical flow reactor was much better than the advection flowreactor.Results of the combined process with advanced oxidation and inducedcrystallization for complxation waterwater treatment showed that the ability fordegradation for EDTA was O₃/UV, O₃/H₂O₂/UV, O₃, O₃/H₂O₂, and O₃/UV under of pHof4.7⁵.0. As for the advanced oxidation with O₃/UV in1hour, the degradation andmineralization rate for EDTA-Cu were65%and53%respectively. O₃/UV（concentration of O₃was40mg/L） was used for the pretreatment of complexationwastewater treatment under the condition that EDTA was100mg/L, copper was38.7mg/L and pH was5, and effluent average concentration of copper was0.43mg/Lafter O₃/UV treatment in1.5h, induced crystallization for0.5h and precipitation andfiltration as well.Results of the combined process with replacement and induced crystallization forcomplxation waterwater treatment showed that as for the treatment of wasterwatercontaining EDTA of100mg/L, copper of37.5mg/L, the average effluent copper was0.45mg/L and COD was less than80mg/L.The complexed copper was released as free copper ion by the pretreatment, andthen could be efficiently removed in the induced crystallization. In a word, the effluentcould satisfy the discharge standard and the heavy metal could also be recoved by the combined process in this study.