Abstract
To investigate optimum starting materials and catalyst loading for conversion of sewage sludge to heavy oil, various kinds of sewage sludges were liquefied at a temperature of 300°C, a pressure of 12 MPa, and a catalyst (sodium carbonate) loading of 0-20 wt %. The optimum kind of sewage sludge was found to be either raw primary sludge or raw mixed sludge because average oil yields of these sludges reached 43 %-higher than those of other kinds of sludges. For most sewage sludges, oil production proceeded satisfactorily without the addition of any catalyst.
