Biodegradation of pentachlorophenol by Flavobacterium species in batch and immobilized continuous reactors

Free and immobilized Flavobacterium sp. were used to degrade pentachlorophenol (PCP) in wastewater in laboratory-scale batch and continuous reactors. Free Flavobacterium sp. in batch reactors completely degraded PCP at concentrations of 30 and 50 mg l−1 but could only partially degrade PCP at 65 mg l−1 concentration. In batch reactors, activated sludge could not degrade PCP but activated sludge mixed with free Flavobacterium sp. exhibited as much degradation capability as that with free Flavobacterium sp. only. Flavobacterium sp. immobilized in alginate in continuous reactors were able to degrade 60 mg l−1 PCP efficiently. The extent of PCP degradation by immobilized Flavobacterium sp. decreased as the influent PCP loading rate increased or as the hydraulic retention time decreased. Efficiency in PCP removal decreased as the food-to-microorganism ratio increased. Immobilized Flavobacterium sp. can tolerate higher concentrations of PCP than free ones. The results indicate the possibility of scaled-up react...