Polyphenol removal from olive mill waste waters by selected mould strains

Abstract

Mould strains were isolated from Olive Mill Waste (OMW) waters, characterized and screened for their activities on polyphenols hydrolysis by reculturing on the olive mill waste waters itself. The selected strains were then used for polyphenols removal in pure culture assays in flasks. Prior to the inoculation, OMW water was diluted to prepare three initial concentrations of polyphenols (2.2 g/L; 4.5g/L; 14.5g/L). Chemical characteristics including polyphenols and Chemical Oxygen Demand (COD) were followed up in these assays. Results showed that the polyphenols removal by some strains was estimated to around 95.14% and the COD was also decreased by 43%. Olive mill waste waters are normally colored in dark because of the polyphenols oxidation. The microbial strains by hydrolysing the polyphenols had decolored completely these effluents and a clear liquid was obtained afier 12-15 days of treatment under aerobic shaking in laboratory. Polyphenols may have some inhibitory effect which would cause problems to the biological treatment of these effluents. Their removal would facilitate the treatment of the waste.