Biofuels & Bioenergy

Olive mill wastewater sludge (OMWS) is one of the major environmental pollutants in olive oil industry using traditional or 3-phase process. The major problem stems from the poor biodegradability of the OMWS because of its high phenolic compounds content. In most Mediterranean countries, olive mill wastewater are stored in ponds where the major part of water evaporates and the sludge dries up which is then later lanfilled for disposal. To resolve this serious environmental problem, we have developed a fluidized bed catalytic pyrolysis of OMWS to produce pyrolysis liquids that are very stable, low viscosity, neutral pH and very high higher heating value. The pyrolysis was conducted at 400-500^oC in a red mud and HZSM-5 catalyst bed. The yields of the organic fraction ranged from 20 to 35 wt% which is much higher than what obtains for other lignocellulosic biomass feedstocks. The viscosity of the oil was 5-7 cP, the pH ranged from 6-7 and the highest HHV of the oil was 41 MJ/kg. The char yield ranged from 20 to 25 wt% while the gas yield ranged from 26-45 wt%. The major challenges with this feedstock were poor flow properties because of its sticky nature, and the strong smell from both old and freshly stored material.