Treatment of high strength distillery wastewater (Cherry stillage) by integrated aerobic biological oxidation and ozonation

The performance of integrated aerobic digestion and ozonation for the treat ment of high strength distillery wastewater (i.e., cherry stillage) is repo rted. Experiments were conducted in laboratory batch systems operating in d raw and fill mode. For the biological step, activated sludge from a municip al wastewater treatment facility was used as inoculum, showing a high degre e of activity to distillery wastewater. Thus, BOD and COD overall conversio ns of 95% and 82% were achieved, respectively. However, polyphenol content and absorbance at 254 nm (A(254)) could not be reduced more than 35% and 15 %, respectively, by means of single biological oxidation. By considering CO D as substrate, the aerobic digestion process followed a Contois' model kin etics, from which the maximum specific growth rate of microorganisms (mu (m ax)) and the inhibition factor, P, were then evaluated at different conditi ons of temperature and pH. In the combined process, the effect of a post-oz onation stage was studied. The main goals achieved by the ozonation step we re the removal of polyphenols and A254 Therefore, ozonation was shown to be an appropriate technology to aid aerobic biological oxidation in the treat ment of cherry stillage.