Wastewater electrooxidation using stainless steel electrodes

Wastewater contains essential nutrients for crops, and after proper treatment its reuse is beneficial to farmers in arid and semi-arid areas. Electrooxidation is an environmentally friendly technology used for treatment of domestic, industrial and agrozootechnical wastewater. During electrooxidation, organic compounds are oxidized at the interface between the anode and the aqueous solution, as a result of the reduction reaction at the cathode. Tests were performed on wastewater collected from the lagoon of a cattle farm, using an electrooxidation cell with stainless steel electrodes. The removal of pH, conductivity, turbidity, color, total N, total P, COD and BOD was investigated at specific voltages of 0.025 V cm-2, 0.05 V cm-2 and 0.1 V cm-2 and various electrolysis times (15, 30, 60 and 120 minutes). Results show that electrooxidation is effective in reducing total N by 24 %, total P by 47 %, BOD by 47 % and COD by 82 %. After completion of tests, the suspended solids were decanted towards the anode area, due to the action of coagulant Fe2+/Fe3+ ions formed by anode dissolution, and the water was clarified. The effluent complies with the standards to be reused to irrigate crops tolerant to salinity grown in permeable soils.