Pretreatment of oily sludge

Wet peroxide oxidation (WPO) and catalytic wet oxidation (CWO) of oily sludge were investigated. Greater than 80% chemical oxygen demand (COD) removal from oily sludge was achieved using sodium carbonate catalysed wet oxidation (WO) under the following conditions using a 0.5 l batch reactor: temperature of 330 degrees C and concentration of sodium carbonate 200 mg/l. Greater than 90% COD removal was achieved using WPO under the following conditions: temperature of 330 degrees C, residence time of 9 min, hydrogen peroxide excess ( HE) of 0.8 and initial COD was 20 000 mg/l. Significantly more COD could be removed from oily sludge when HE was 0.8. BOD5/COD ratio was 0.52 after the oily sludge had been treated. It was concluded that WPO was a far more effective pretreatment method for removing organic compounds from oily sludge.