BACKGROUND: Olive 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.
RESULTS:The 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 H 2 O 2 , 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 Fe 2+ (but no H 2 O 2 ) was added, the COD, TOC, phenol, and colour removal efficiencies were 74, 54, 79, and 72%, respectively.
CONCLUSION: PHVD can be used to effectively treat OOMW, using a combination of physical and chemical effects initiated by the electrical discharge into the water.Pilot-scale pulsed high-voltage discharge system A diagram of the PHVD system is shown in Fig. 1. A high-voltage power supply with two rotating spark-gap switches was used to generate the high-voltage pulses. A series of diodes was used to convert alternating current (AC) to direct current (DC). A high-voltage power supply provided a peak voltage in the range 0-24 kV and pulse frequency in the range 0-50 Hz. Four stainless steel 1 mm i.d. needles were inserted into the reactor, from