Combination of hydrodechlorination and biodegradation for the abatement of chlorophenols

A method for abatement for chlorophenols (CPs) in contaminated water based on successive steps of catalytic hydrodechlorination (HDC) over Pd/C at ambient temperature and pressure, followed by aerobic biodegradation using yeast Candida tropicalis (C. tropicalis) was studied. The results showed that 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) could be easily and completely dechlorinated under mild conditions, ultimately yielding phenol as product. Subsequently, phenol (0-900 mg L-1) could be completely degraded by C. tropicalis within 30 h. Moreover, during the biodegradation of phenol, definite mass of ethanol (<= 0.5%) caused a modest increase in the duration of the lag phase, but led to a great increase in the maximum degradation rates. This means that CPs with higher concentration could be efficiently detoxified under mild conditions by a combination of HDC and biodegradation in water or water-ethanol systems.