Ozonation of phenolic wastewaters in the presence of a perovskite type catalyst

The ozonation of different wastewaters has been carried out in the presence of perovskites. Wastewaster A (a mixture of syringic, pyruvic and gallic acids in water) was firstly ozonated for 30 min in the absence of the catalyst. Thereafter, the solid was added to the solution and the effect of the main operating variables investigated. Catalyst activity and stability was confirmed by consecutive experiments with the same solid. Concentration of perovskites did show no appreciable influence for values above 0.1 g L-1. Additionally, the higher the initial chemical oxygen demand, the higher the observed removal rate. Mineralization level was favoured by temperature while pH did exert a positive effect when raising this parameter to values as high as 11. No clear trend after free radical scavengers addition could be envisaged for the catalytic experiments. Wastewaters B (from wine distillery), C (from olive debittering) and D (from olive oil production) showed different behaviours depending on their nature. Thus, activity of perovskites in the ozonation process was only experienced for those effluents showing a certain refractory character towards single ozonation. No differences were observed between catalytic and non-catalytic runs for easily oxidised wastewaters. (C) 2007 Elsevier B.V. All rights reserved.