Electrochemical oxidation of a textile dye wastewater using a Pt/Ti electrode

Textile dye wastewater (TDW) from a reactive, azo dyeing process was treate d by an electrochemical oxidation method using Ti/Pt as anode and stainless steel 304 as cathode. Due to the strong oxidizing potential of the chemica ls produced (chlorine, oxygen, hydroxyl radicals and other oxidants) when t he wastewater was passed through the electrolytic cell the organic pollutan ts were oxidized to carbon dioxide and water. A number of experiments were run in a batch, laboratory-scale, pilot-plant, and the results are reported here according to residence time and initial addition of HCl in raw wastew ater. When of 2 ml of HCl 36% were added and after 18 min of electrolysis a t 0.89 A/cm(2), chemical oxygen demand (COD) was reduced by 86%, biochemica l oxygen demand (BOD,) was reduced by 71%, ADMI color units were reduced by 100%, and TKN was reduced by 35%. The biodegradability of the wastewater w as improved because the COD/BOD ratio decreased from 2.16 to 1.52. At the s ame time the efficiency of the electrode was about 170 g h(-1) A(-1) m(-2). and the mean energy consumption was 21 kW h/kg of GOD. These results indic ate that this electrolytic method could be used for effective TDW oxidation or as a feasible detoxification and color removal pretreatment stage for b iological post treatment. (C) 1999 Elsevier Science B.V. All rights reserve d.