Aerobic biological treatment of black table olive washing wastewaters: effect of an ozonation stage

Abstract

The present work is a study of oxidative degradation of the organic matter present in the washing waters from the black table olive industry. Pollutant organic matter reduction was studied by an aerobic biological process and by the combination of two successive steps: ozonation pretreatment followed by aerobic biological degradation. In the single aerobic biological process, the evolution of biomass and organic matter contents was followed during each experiment. Contaminant removal was followed by means of global parameters directly related to the concentration of organic compounds in those effluents: chemical oxygen demand (COD) and total phenolic content (TP). A kinetic study was performed using the Contois model, which applied to the experimental data, provides the specific kinetic parameters of this model: 4.81×10 −2 h −1 for the kinetic substrate removal rate constant, 0.279 g VSS g COD −1 for the cellular yield coefficient and 1.92×10 −2 h −1 for the kinetic constant for endogenous metabolism. In the combined process, an ozonation pretreatment is conducted with experiments where an important reduction in the phenolic compounds is achieved. The kinetic parameters of the following aerobic degradation stage are also evaluated, being 5.42×10 −2 h −1 for the kinetic substrate removal rate constant, 0.280 g VSS g COD −1 for the cellular yield coefficient and 9.1×10 −3 h −1 for the kinetic constant for the endogenous metabolism.