Effect of key operating parameters on the non-catalytic wet oxidation of olive mill wastewaters

摘要

The non-catalytic wet air oxidation (WAO) of olive mill wastewaters was investigated. The effect ofnoperating conditions, such as initial organic loading (1,000 and 4,500mg/L COD), reactionntemperature (140 and 1808C), treatment time (1 and 4 h), initial pH (4.8 and 7) and the use ofn500mg/L H2O2 as an additional oxidant, on treatment efficiency was assessed implementing anfactorial experimental design. Of the five parameters tested, the first two had a considerable effectnon COD removal, while treatment time was of no significance implying that all oxidation reactionsnoccur during the first hour of treatment. Although the level of mineralization was generallynmoderate, this was accompanied by nearly complete total phenols and color removal. The analysisnwas repeated at more intense conditions, i.e. initial COD up to 8,000mg/L and reactionntemperature up to 2008C; at this level, none of the studied effects were important. However, atnoptimal experimental conditions (i.e. 1808C, 1 h treatment and initial COD of 8,100mg/L) WAOnyielded 34, 94 and 74% removal of COD, total phenols and color respectively. Moreover,necotoxicity to V. fischeri was slightly reduced after 2 h of treatment at the above conditions.