Treatment of 1,2,4 -acid wastewater combined flocculation with complex extraction process

Combined flocculation with complex extract process to treat with 1,2,4-acid wastewater. Dicyandiamide formaldehyde was used as the flocculant; TOA(trioctylamine) as extracting agent, propyl butyl-carbinol as the diluent, NaOH as back-extracting agent. The best flocculation conditions are: pH value of the wastewater is 3, formaldehyde Dicyandiamide to wastewater at the ratio of 1%, stirred quickly for 2 min and slowly for 10 min at 70 °C, standing for 40 min. The best extraction conditions are: the concentration of extractant is 40%, O/A = 1∶6, the pH value of wastewater for 1.5. The optic back-extraction conditions are: NaOH concentration is 15%, (B/O) = 1∶2. The COD removal rate reaches to 97.77%, and the wastewater can be discharged according to national Standard.