BACKGROUNDOlive oil mill wastewaters (OOMW) have caused major environmental problems because of the high organic load, high total suspended solids, high inert chemical oxygen demand (COD), low pH, a characteristic odour, its dark colour and toxicity to plants. A pulsed high-voltage discharge (PHVD) process was developed as a novel alternative to advanced oxidation processes for effective treatment of OOMW. RESULTSThe ability of a PHVD process, after acid cracking, to treat OOMW, was investigated. For a PHVD treatment time of 60 min the chemical oxygen demand (COD), total organic carbon (TOC), phenol, and colour removal efficiencies were 21, 31, 23, and 32%, respectively. Following the addition of 63 mmol L-1 H2O2, the COD, TOC, phenol, and colour removal efficiencies reached 72, 55, 74, and 82%, respectively, for the same treatment time. When 0.37 mmol L-1 Fe2+ (but no H2O2) was added, the COD, TOC, phenol, and colour removal efficiencies were 74, 54, 79, and 72%, respectively. CONCLUSIONPHVD can be used to effectively treat OOMW, using a combination of physical and chemical effects initiated by the electrical discharge into the water. (c) 2014 Society of Chemical Industry