Removal of Olive Mill Wastewater Phenolics with the Use of a Polyphenol Oxidase Homogenate from Potato Peel Waste

Abstract EN

Olive mill wastewater (OMW) originating from a two-phase olive oil producing plant was treated with a crude polyphenol oxidase (PPO) homogenate, prepared from potato waste peels.

The treatments carried out were based on a 23-full-factorial, central composite design (CCD) in order to identify optimal operational conditions with regard to polyethylene glycol (PEG) concentration, pH, and treatment duration.

The treatment performance was assessed by estimating the % reduction in total polyphenol (TP) concentration.

The model obtained produced a satisfactory fitting of the data (R2=0.96, P=0.0017).

The utilisation of the predictive model enabled the theoretical calculation of the optimal set of conditions, which were pH=4, t=3.57 h, and [PEG] = 900 mg L−1.

Under these conditions, the optimal theoretical % removal calculated was 54±9.

Examination of the treated samples with high-performance liquid chromatography (HPLC) showed that the potato homogenate afforded changes in the polyphenolic profile.

Based on the experimental evidence, oxidation pathways were proposed.