Electrochemical treatment in relation to pH of domestic wastewater using Ti/Pt electrodes.

This paper describes an electrochemical treatment of domestic wastewater (DW) using 0.8% (w/v) sodium chloride as electrolyte. In this technique, DW was passed through an electrolytic cell using Ti/Pt as anode and Stainless Steel 304 as cathode. Due to the strong oxidizing potential of the chemicals produced (chlorine, oxygen, hydroxyl radicals and other oxidants), the organic pollutants and nutrients (organic nitrogen, phosphorous) were wet oxidized to carbon dioxide, and nitrogen as well as phosphorous was precipitated as Ca(3)(PO(4))(2). Experiments were run in a continuous, laboratory-scale, pilot plant, at 40 degrees C and the efficiency of oxidation was studied in relation to pH. It was found that in alkaline conditions the electrolysis was more efficient. At pH 9, NaCl concentration 0.8% (w/v), current density 0.075 A/cm(2) and for 1h of electrolysis, COD was reduced by 89%, volatile suspended solids (VSS) by 90%, ammonia nitrogen by 82% and total phosphorous by 98%. The efficiency of electrolysis went up to 35 g COD(r)/(hm(2)A) and the energy consumption to 12.4 kWh/kg COD(r). It is concluded that the application of electrolytic oxidation of DW is more advantageous compared to conventional biological treatment especially for small works.