The three primary objectives of this research project were: to establish the ion-exchange capacity of Norit GAC for perchlorate; to establish that perchlorate at low ug/L concentrations can be biologically removed to below the limit of detection (2.0 ug/L) using BAC filtration; and, to determine a correlation between nitrate concentration and level of perchlorate removal. Granular activated carbon, biologically active carbon, influent water, perchlorate, electron donor solution, dissolved oxygen concentration, bromate, nitrite, nitrate analyses, perchlorate analysis, dissolved oxygen analysis, and ammonia analysis are discussed.