Using Ozonation as an Advanced Oxidation Process for Reduction of Biological Sludge in Wastewater Treatment Unit of Bandar Abbas Refinery

Considering the development of refining industries, the ability of the treatment of heavy crude oil with high sulfur, salt, heavy metals, and other undesirable conditions, and the severity of environmental standards, the treatment of refinery wastewater and the disposal of remaining sludge is more difficult than before. With the development of wastewater treatment processes, nowadays more attention are paid to advanced oxidation processes (AOPs). In this work, ozonation as an advanced oxidation process is used for the reduction of biological sludge of Bandar Abbas refinery wastewater. Samples of returned sludge to oxidation basin were ozonated for 20-120 minutes with an amount of 0.0516 to 0.6192 mgO3/mgTSS and in each case COD and remained sludge were defined. The results show that ozone can reduce the amount of sludge and COD with an improvement in the settling conditions. The best conditions were in case of ozone injection for 80 minutes at 0.4128 mgO3/mgTSS. This case can reduce the final sludge up to 36.67% and in this condition COD was reduced from 15570mg/l to 8920mg/l with a 42.71% reduction. Considering the monthly production of 40-50 tons of excess sludge in Bandar Abbas refinery, using this procedure can reduce the final sludge up to 18 tons/month with reducing environmental hazards with the minimization of the waste management costs.