Catalytic pyrolysis of Olive Mill WAastewater Sludge

Olive mill wastewater sludge (OMWS) is the solid residue that remains in the evaporation ponds after evaporation of the majority of water in the Olive mill wastewater (OMW). OMWS is a major environmental pollutant in the olive oil producing regions. It has a bad smell, phytotoxic effect on plants, and can cause sterility of the land where it is stored. Catalytic pyrolysis can be potentially used to convert this material into fuels and simultaneously solve the environmental pollution problem. Two catalysts (fresh red mud and HZSM-5) were evaluated for converting the OMWS into liquid fuel. Depending on the reaction temperature (400-500 C), the fresh red mud yielded more organics (20 to 25 wt.%, dry basis) than the equivalent HZSM-5, whereas HZSM-5 yielded more permanent gases (19 to 35 wt.%, dry basis) than the red mud. The viscosity, pH, and HHV of the red mud catalytic pyrolysis oils were 4.6 to 9.7 cP, 7.1 to 7.4, and 39.5 to 41.3 MJ/Kg, respectively. For HZSM-5 catalytic pyrolysis oils, the viscosity, pH, and HHV were respectively 6.2 to 8.2 cP, 6.4 to 7.0, and 38.4 to 38.9 MJ/Kg. Carbon dioxide and hydrogen counted for the highest fraction (mole basis) of the gas product from the HZSM-5 and red mud catalyzed pyrolysis, respectively. The gaseous hydrocarbons yield (mole basis) from HZSM-5 catalyzed pyrolysis was over three times higher than that from red mud catalyzed pyrolysis. However, the hydrogen yield from red mud catalyzed reaction was over 8 times higher than that from HZSM-5. Because of the excellent properties of the catalytic pyrolysis liquids, they could be potentially used as a green diesel fuel