Wet oxidation of debarking water: changes in lignin content and biodegradability

The purpose of the research was to estimate optimal conditions for wet oxidation (WO) of debarking water from the paper industry. The WO experiments were performed at various temperatures, partial oxygen pressures and pHs. The experiments showed that lignin degradation and organics removal are affected remarkably by temperature and pH. At different WO conditions (pH 12, T 130-200A degrees C), 78-97% of lignin reduction was detected. pH value of 12 caused faster removal of tannins/lignin content; pH value of five was more effective for removal of total organics, represented by chemical oxygen demand (COD) and total organic carbon. The highest biodegradability [biological oxygen demand (BOD)/COD] of 0.72 was obtained at a pH of ten and temperature of 200A degrees C.