Biodegradation of olive mill wastewater phenolic compounds in a thermophilic anaerobic upflow packed bed reactor and assessment of their toxicity in digester effluents.


Department of Chemical Engineering, University of Patras, GR 26504, Rion, Patras, Greece. Electronic address: [Email]


The extent of phenolic compounds' biodegradation was assessed utilizing un-treated olive mill wastewater (OMWW) fed to a high-rate thermophilic (55 οC) anaerobic upflow packed bed reactor (UPBR) and digester effluents (DEs) collected in different hydraulic retention times (HRTs) under steady-state operating conditions. In parallel, the toxicity of each sample was evaluated by performing the microbiotest Thamnotoxkit F™. The outcomes indicate complete biodegradation of 6 phenolic compounds-vanillic acid (VA), caffeic acid (CA), syringic acid (SA), o-coumaric acid (o-CA), oleuropein (OLEU), 4-ethylphenol (4-EP)-and notable removals of hydroxytyrosol (HT) and tyrosol (TYR), reaching up to 94.87 ± 0.04% and 93.92 ± 0.33%, respectively. 4-hydroxybenzoic acid (PHBA), p-coumaric acid (p-CA) and 3,4-dihydroxybenzoic acid (DBA) were recognized as the most recalcitrant and persistent compounds in the anaerobic effluents, being capable of modulating the toxic potential of DEs.


Anaerobic digestion,Biodegradation,Olive mill wastewater (OMWW),Phenolic compounds,Toxicity,

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