MODELLING INDUSTRIAL WASTEWATERS OZONATION IN BUBBLE CONTACTORS: SCALE-UP FROM BENCH TO PILOT PLANT

摘要

A kinetic model constituted by ozone mol balance equations both in the gas and in the water and a total mol balance equation has been applied to predict concentrations of dissolved ozone, C_(O3), ozone partial pressure at the reactor outlet, P_(O3o), and remaining chemical oxygen demand, COD, for the ozonation of two industrial wastewaters released from distillery and tomato processing plants.The results showed good agreement with the experimental ones when applied to contactors of same height/diameter ratio. Deviations were less than 5%, 10 % and 10 % for COD, C_(O3) and P_(O3o),respectively. Similar deviations were also found when the model was applied to the ozonation in a bubble column for reaction times higher than 15 minutes. For the short initial reaction period deviations were much higher possibly due to incorrected values of mass transfer and reaction rate coefficients, the latter especially in the ozonation of tomato wastewaters.In all cases, however, the model predicts very well the experimental oxidation and ozone efficiencies. For these cases deviations were lower than ± 3 %.