Ozonation of black-table-olive industrial wastewaters: effect of an aerobic biological pretreatment

The present work is a study of oxidative degradation of the organic matter present in the washing waters from the black-table-olive industry. This oxi dation is performed by an ozonation process, by an aerobic biological degra dation process, and by another ozonation of biologically pretreated washing waters. In the ozonation process, a second-order kinetic reaction with res pect to ozone and COD or aromaticity has been deduced. The kinetic rate con stants were correlated as a function of temperature by Arrhenius-type equat ions. In the aerobic biological treatment, a kinetic study was performed us ing the Contois model, giving a value of 4.8 10(-2) h(-1) for the kinetic b ioreaction constant. Likewise, a cell yield coefficient of 0.30 g VSSg COD- 1 and a kinetic constant for the endogenous metabolisme of 1.2 10(-2) h(-1) were deduced. Finally, in the ozonation of biologically pretreated wash-wa ters, the deduced kinetic rate constants for COD and aromaticity were, resp ectively, 4.5 and 2.4 times higher that those corresponding to the ozonatio n of wash-waters without biological pretreatment. (C) 2000 Society of Chemi cal Industry.