Abstract
Olive oil production generates large volumes of wastewater. These wastewaters are characterised by high chemical oxygen demand (COD), high content of microbial growth-inhibiting compounds such as phenolic compounds and tannins, and dark colour. The aim of this study was to investigate biodegradation of olive mill wastewater (OMW) by yeasts Trichosporon cutaneum and Geotrichum candidum. The yeast Trichosporon cutaneum was used because it has a high potential to biodegrade phenolic compounds and a wide range of toxic compounds. The yeast Geotrichum candidum was used to see how successful it is in biodegrading compounds that give the dark colour to the wastewater. Under aerobic conditions, Trichosporon cutaneum removed 88 % of COD and 64 % of phenolic compounds, while the dark colour remained. Geotrichum candidum grown in static conditions reduced COD and colour further by 77 % and 47 %, respectively. This investigation has shown that Trichosporon cutaneum under aerobic conditions and Geotrichum candidum under facultative anaerobic conditions could be used successfully in a two-step biodegradation process. Further investigation of OMW treatment by selected yeasts should contribute to better understanding of biodegradation and decolourisation and should include ecotoxicological evaluation of the treated OMW.
Highlights
Olive oil production generates large volumes of wastewater
Literature reports about degradation of phenol (2124) and phenolic compounds extracted from olive mill wastewater (OMW) [24] by the yeast Trichosporon cutaneum
OMW was biodegraded by T. cutaneum under aerobic conditions and at pH 6.0 to 6.5
Summary
Olive oil production generates large volumes of wastewater These wastewaters are characterised by high chemical oxygen demand (COD), high content of microbial growth-inhibiting compounds such as phenolic compounds and tannins, and dark colour. The aim of this study was to investigate biodegradation of olive mill wastewater (OMW) by yeasts Trichosporon cutaneum and Geotrichum candidum. Geotrichum candidum grown in static conditions reduced COD and colour further by 77 % and 47 %, respectively This investigation has shown that Trichosporon cutaneum under aerobic conditions and Geotrichum candidum under facultative anaerobic conditions could be used successfully in a two-step biodegradation process. Treatment and reuse of OMW presents significant challenges both due to the nature of olive oil production and due to the characteristics of the wastewater (high COD, high phenolic content, and dark colour) [13]. Other yeasts of the genus Geotrichum [12, 13, 15, 25,26,27], Candida [7, 10, 28] and Yarrowia [28], moulds [13, 25] and white-rot fungi [13, 25] have been investigated in studies of OMW biodegradation
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