TREATMENT OF FOOD INDUSTRY EFFLUENTS IN AERATED SUBMERGED BIOLOGICAL FILTERS
A mixed wastewater from different food-processing industries has been treated in two pilot-scale aerated submerged biological filters. Plastic media with specific surface areas of 140 m2/m3 and 230 m2/m3, respectively, were used. A maximum volumetric removal rate in excess of 15 kg COD/m3d was obtained with the 230 m2/m3filter medium. In order to perform properly the biofilters needed a minimum bulk liquid dissolved oxygen concentration of 2 mg/lO2.