Oxidative transformation of aqueous phenolic mixtures by birnessite-mediated catalysis.

The catalytic efficiency of birnessite in the removal of catechol, hydroxytyrosol, methylcatechol and m-tyrosol, four phenols commonly present in polluted wastewaters, was studied in mono-substrate solutions or in mixtures of two, three, and four substrates. In single phenolic solutions the transformation order of phenols was catechol>hydroxytyrosol>methylcatechol>m-tyrosol. With phenolic mixtures different responses were observed and the amount of each phenol transformed and the crossing effects among the various phenols depended on the type and number of phenols present in the mixture.

Oxidative transformation of natural and synthetic phenolic mixtures by Trametes versicolor laccase.

The efficiency of Trametes versicolor laccase in the transformation of phenols (caffeic acid, catechol, hydroxytyrosol, methylcatechol, protocatechuic acid, syringic acid, m-tyrosol, 3-hydroxybenzoic acid, 3-hydroxyphenylacetic acid, 2,6-dihydroxybenzoic acid, 4-hydroxybenzaldehyde) usually present in waste water, such as that derived from an olive oil factory, was investigated. According to their response to 24 h laccase action the 11 phenolic compounds were classified in three groups: reactive (88-100% transformation), intermediate reactive (transformation lower than 50%), and recalcitrant (not transformed at all). The enzyme was able to transform the 11 substrates even when they were present in a mixture and also toward a phenolic extract from a Moroccan olive oil mill waste water (OMW) sample.

Mitigation of olive mill wastewater toxicity.

The toxicity of olive mill wastewaters (OMW) is commonly attributed to monomeric phenols. OMW were treated in an aerated, stirred reactor containing agricultural soil, where the oxidative polymerization of phenols took place. In 24 h, OMW monomeric phenols decreased by >90%.