Study on Pretreatment of Cationic Dye Wastewater

The electric-flocculated reactor could be used for the pretreatment of cationic dye wastewater at dye plant.The flocculation efficiencies of the coagulating reagents,including polyaluminum chloride(PAC),ferrous sulfide,polymeric ferric sulfate,calcium hydroxide and sorbent,were compared each other when added to the outflow wastewater from electric-flocculate.The efficiency by adding Fenton's reagent was also studied.The results showed that,the optimal conditions were the solution pH 5,retention time 30 min,current 6 A;the color removal rate by absorbent was above 99.9%.The color and COD can be removed effectively by the Fenton's reaction when the quantity of H2O2 reached 5%,their total removal rates were respectively 99.9% and 47.6%.The biodegradability of wastewater was improved obviously after the Fenton's reaction.The BOD5/COD value was increased from 0.26 to 0.47,about 80.8% higher;the basic operation cost of this design technology was 8.44 Yuan per ton wastewater.