"This research project was designed to identify process wastewaters which contained a significant proportion of the total load of contaminants in petroleum refinery wastewaters and to evaluate methods for intensively treating these highly concentrated low volume streams. In addition, selected waste residues from API gravity separator, dissolved air flotation units, and "slop" oil emulsions were analyzed to determine the presence of hazardous chemicals as listed by the U.S. Environmental Protection Agency (EPA) Office of Solid Waste. Process wastewaters from the fluid catalytic cracking units, crude desalting unit, coking unit, and barometric condenser contained the highest levels of contaminants. These process wastewater streams were major contributors to the total load of phenol, ammonia, sulfide, and organic carbon contamination of the combined refinery wastewaters. On-site evaluations of mixed media filtration-activated carbon adsorption and a biological oxidation system indicated both systems were capable of reducing phenol, sulfide, and organic carbon levels by greater than 90 percent."