Integrated aerobic biological treatment and chemical oxidation with Fenton’s reagent for the processing of green table olive wastewater

Abstract

Table olive processing wastewater (TOPW) is unsuitable for disposal at municipal or industrial wastewater treatment plants due to its high organic and phenol content. Aerobic biological treatment using an Aspergillus niger strain in a bubble column bioreactor in combination with chemical oxidation was studied for the management of TOPW to a quality which corresponds to the input standards for wastewater treatment plants (COD<1200 ppm, BOD<500 ppm). After 2 days of biological treatment COD was reduced by 70%, while the total and simple phenolic compounds were decreased by 41 and 85%, respectively. In the chemical treatment step, the effect of different H 2O 2 concentrations on the patterns of COD and phenol reduction was studied. The main effect of the chemical oxidation step was the elimination of persistent phenolic compounds during the biological treatment of total phenolic compounds. Coagulation with CaO significantly improved the efficiency of the process.