LOW-TEMPERATURE THERMAL-TREATMENT FOR PETROLEUM REFINERY WASTE SLUDGES

Treatment requirements for waste sludges generated by petroleum refinery operations and designated as waste codes K048, K049, K050, K051 and K052 under the Resource Conservation and Recovery Act (RCRA) became effective in November, 1990 under the "Landban" regulations. An experimental program evaluated low temperature thermal treatment of filter cakes produced from these sludges using laboratory and pilot-scale equipment. One set of experiments on waste samples from two different refineries demonstrated the effective removal of organics of concern from the sludges to meet the RCRA Best Demonstrated Available Technology (BDAT) treatment standards. Cyanides were also within the acceptable limit. Combined with stabilization of heavy metals in the treatment residues, low temperature thermal treatment therefore provides an effective and efficient means of treating refinery sludges, with most hydrocarbons recovered and recycled to the refinery. A milder thermal treatment was used to remove the bulk of the water from a previously filtered waste sludge, providing effective waste minimization through a 40% decrease in the mass of sludge to be disposed. The heating value of the sludge was increased simultaneously by one-third, thereby producing a residue of greater value in an alternative fuels program. A process based on this approach was successfully designed and commercialized.