Experimental study on the recovery of nitrogen and phosphorus from electroplating wastewater by struvite crystallization method

Abstract

The nitrogen and phosphorus in electroplating wastewater were recovered using struvite crystallization method. The effects of pH, concentration of heavy metal ions and mass concentration of fluoride ions on the removal of nitrogen and phosphorus in electroplating wastewater were investigated. The results showed that pH and concentration of heavy metal ions had significantly affect on the process of struvite crystallization, while the effect of low mass concentration（0-40 mg/L） of fluoride ions on the structure of struvite could be ignored. XRD, SEM and XPS characterization were conducted on struvite formed under different conditions, and the influence mechanism of heavy metal ions and fluorine ions on the crystallization process of struvite was analyzed. Heavy metal ions could co-precipitate with struvite and interfere with the formation of struvite crystals. When fluoride ions coexisted with heavy metal ions, fluoride ions would interfere the adsorption of heavy metal ions on the crystal, and generate amorphous phase coprecipitates, changing the crystal morphology of struvite. This study provides a theoretical basis for the recovery of nitrogen and phosphorus from electroplating wastewater by the struvite crystallization method.

Keywords

• electroplating wastewater
• heavy metal ions
• fluoride ions
• struvite