Method for treating electroplating wastewater

A method for treating electroplating wastewater, comprising:

• adding to-be-treated cyanide containing wastewater into a cyanide primary treatment tank, and performing a cyanide primary treatment on the to-be-treated cyanide containing wastewater in the cyanide primary treatment tank to obtain primary treated wastewater;
• wherein a process of the cyanide primary treatment comprises:
• under a stirring condition, adding alkali liquor into the to-be-treated cyanide containing wastewater to adjust a power of hydrogen (pH) value of the to-be-treated cyanide containing wastewater to a first preset alkaline range, and adding a sodium hypochlorite solution into the to-be-treated cyanide containing wastewater simultaneously to adjust an oxidation-reduction potential (ORP) of the to-be-treated cyanide containing wastewater to obtain a first mixture;
• and allowing the first mixture to react at room temperature for a period of time and retain for a period of time, to thereby obtain the primary treated wastewater;
• and the primary treated wastewater comprises a remaining amount of chlorine;
• performing a cyanide secondary treatment on the primary treated wastewater to obtain secondary treated wastewater;
• wherein a process of the cyanide secondary treatment comprises:
• adding chromium containing wastewater into the primary treated wastewater, controlling an additive amount of the chromium containing wastewater and adding acid liquor into the primary treated wastewater simultaneously to adjust a pH value of the primary treated wastewater to a first preset acidity range to obtain a second mixture;
• and allowing the second mixture to react at room temperature for a period of time and retain for a period of time, to thereby obtain the secondary treated wastewater;
• and the secondary treated wastewater comprises a remaining amount of chromium;
• performing a hexavalent chromium reduction treatment on the secondary treated wastewater to obtain reduction treated wastewater;
• wherein a process of the hexavalent chromium reduction treatment comprises:
• under a stirring condition, adding acid liquor into the secondary treated wastewater to adjust a pH value of the secondary treated wastewater to a second preset acidity range, and adding a sulfite solution into the secondary treated wastewater simultaneously to adjust an ORP of the secondary treated wastewater to be suitable for performing the hexavalent chromium reduction treatment, to thereby obtain a third mixture;
• and allowing the third mixture to react at room temperature for a period of time to reduce hexavalent chromium to trivalent chromium and retain for a period of time, to thereby obtain the reduction treated wastewater;
• and the reduction treated wastewater comprises a remaining amount of sulfite;
• and
• performing neutralization flocculation, solid-liquid separation, and sand filtration on the reduction treated wastewater sequentially to obtain dischargeable water meeting a preset standard.