In recognition of public concern over environmental quality, Congress passed the Water Pollution Control Act (PL 92-500) in 1972. The stated objective of this act was" to restore and maintain the chemical, physical, and biological integrity of the nation's waters". Toward this end US industry was required to apply Best Practicable Control Technology Currently Available (BPCTCA) to treat industrial effluents. Effluent limitation guidelines rePresenting the degree of effluent contaminant reduction attainable by the application of BPCTCA were established by the US Environmental Protection Agency (EPA) under the authority of Sections 301 and 304 of the Act. To meet BPCTCA effluent quality standards, secondary biological treatment, such as activated sludge, was often required to follow primary physical and chemical treatment, such as filtration, flocculation, chemical precipitation, or adsorption. The Water Pollution Control Act was amended in 1977 as the Clean Water Act (PL 95-217). This act established 1 July 1984 as the deadline for application of more stringent Best Available Technology Economically Achievable (BATEA) to the treatment of industrial effluents. The EPA in 1975 indicated that BATEA was considered to be secondary biological treatment followed by tertiary granular activated carbon (GAC) adsorption as a polishing step (US Environmental Protection Agency, 1975). Adding on GAC adsorption columns to existing biological treatment facilities involves large capital expenditures and increased operating costs. Not surprisingly there has been a great deal of activity in industry directed toward finding less expensive ways of meeting the BATEA guidelines. One process which has been demonstrated to be both a technically and economically viable alternative to tertiary GAC adsorption is the direct addition of powdered activated carbon (PAC) to a biological treatment facility. Most of the work in this area involves PAC addition to an activated sludge system. It is the purpose of this paper to review the available literature concerning this process.