Use of ozone and hydrogen peroxide in the post-treatment of UASB treated alkaline fruit cannery effluent

UASB treatment of cannery effluents was shown to be feasible. However, the treated effluent still does not allow direct discharge to a water system an d a further form of post-treatment is necessary to reduce the COD to lower than the legal limit of 75 mg/l. The use of ozone, hydrogen peroxide and gr anular activated carbon were used singly or in combination to assess the ef fectiveness as post-treatment options for the UASB treated alkaline fruit c annery effluent. Colour reduction in the effluent ranged from 15% to 92% an d COD reductions of 26-91% were achieved. Combinations of ozone and hydroge n peroxide gave better results than either oxidant singly. The best results were achieved by combining ozone, hydrogen peroxide and granular activated carbon, and COD levels were reduced to levels sufficiently below the 75 mg /l limit.