FLUIDIZED-BED BIOFILMS FOR CHLOROPHENOL MINERALIZATION

This paper summarizes a five-year research effort on the development o f a high-rate fluidized-bed biofilm system for remediation of chloroph enol contaminated groundwater. Laboratory-scale experiments with model compounds and actual contaminated groundwater included studies on aer obic and anoxic treatment, strategies for selective enrichment of chlo rophenol degrading microorganisms, kinetics and stoichiometries of chl orophenol conversions, toxicity removal, growth and culture characteri zation, recovery from process upsets, and operation at suboptimal temp eratures. The aerobic process using chlorophenols as the sole source o f carbon and energy showed the greatest versatility and efficiency. Th e contaminated groundwater consisted of 2,3,4,6-tetrachlorophenol, 2,4 ,6-trichlorophenol and pentachlorophenol with total chlorophenol conce ntrations ranging from 45 to 55 mg/l, At room temperature, groundwater remediation resulted in over 99.9% mineralization at chlorophenol loa ding rates of 1000 mg/l/d and hydraulic retention times of less than 1 h. At the groundwater temperature (7 degrees C), similar removal effic iencies were obtained at chlorophenol loading rates of up to 740 mg/l/ d. The laboratory results were successfully repeated in an on-site, pi lot-scale demonstration.