Treatment of toluene, benzene, naphthalene and xylene (BTNXs) containing wastewater using improved biological oxidation with pretreatment using Fenton/ultrasound based processes

Improved biological oxidation based on pretreatment using combined Fenton and ultrasound in presence of stirring as the best approach and use of modified activated sludge was demonstrated for the treatment of wastewater containing benzene, toluene, naphthalene and o-xylene. The optimum pretreatment conditions were observed as initial pH of 3-3.5, Fe2+ dosage of 2.0 g L-1 and H2O2 dosage of 1.0 g L-1 giving about 80-95% reduction in the chemical oxygen demand (COD) and favorable BOD5/COD value for the biological oxidation. Use of modified prepared activated sludge gave about 20-30% higher extent of degradation as compared to the conventional sludge types.