FIELD-EVALUATION OF A GRANULAR ACTIVATED CARBON FLUID-BED BIOREACTOR FOR TREATMENT OF CHLOROBENZENE IN GROUNDWATER

Although granular activated carbon (GAC), fluidized-bed bioreactors ha ve been used for treatment of ground water containing readily biodegra dable organic compounds, there is only limited experience with treatme nt of chlorinated organics found at many industrial sites. This paper describes a field evaluation of a GAC fluid-bed bioreactor operated at various chlorobenzene concentrations and organic loading rates over a 7-month period. Microorganisms used to seed the bioreactor were provi ded by activated sludge from the site, as well as indigenous chloroben zene-degrading bacteria present in the groundwater. Removal efficienci es exceeding 99.99% were achieved at organic loading rates between 6 a nd 10 pounds of total oxygen demand (Ib TOD) per 25 cubic feet per day . Influent chlorobenzene concentrations ranging from 100 to 170 ppm we re consistently reduced to below the detection limit of 20 ppb. Econom ic evaluation indicates that groundwater treatment costs for the biore actor were lower than other conventional technologies.