IMMOBILIZED-CELL DEGRADATION OF CHLOROPHENOLS

The ability of immobilized cells grown under oxic and fluidized conditions to degrade 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) is evaluated under different dilute rate conditions. Microcarriers with 6.5-u, pores are employed for cell immobilization and retention. Results indicate that, with feed 4- CP and 2,4-DCP concentrations at 35.7 and 45.3 mg/1, respectively, good and stable removal performance is achievable at empty-bed hydraulic retention times as low as one hour. Stoichiometric release of chloride and removal of total organic carbon are also observed, implying that complete mineralization of 4-CP and 2,4- DCP is attainable. This observation is further validated with the gas-chromatography/mass-spectrometry (GC/MS) data obtained in the 2,4-DCP experimentation. Colonization of immobilized cells on the microcarrier surface is a slow but selective process. Extensive growth of filamentous bacteria is observed, with rodshaped bacteria grown underneath and adhered to the filaments. Detachment of immobilized cells from the microcarrier surface is negligible. The formation of microbial films on the microcarrier surface with measurable thickness is absent. © ASCE.