Metal toxicity on the dechlorination of monochlorophenols in fresh and acclimated anaerobic sediment slurries

The biotransformation of 2- and 3-chlorophenol(CP) was examined in anaerobic fresh and acclimated sediments in the presence and absence of CuCl₂, CdCl₂ and K₂Cr₂O₇ ranging from 10 to 200 mg/l. Differing inhibitory effects of specific metals were observed on dechlorination of CPs in sediment slurries. In case of fresh unacclimated slurry, addition of 20 mgCu/l resulted in no appreciable inhibition of dechlorination for tested CPs. In contrast, 20 mg/l of Cd and Cr moderately affected lag periods prior to dechlorination. In this case, Cd was more inhibitory than either Cu or Cr (Cd > Cr ≥ Cu), which illustrated nearly similar effect.

In case of acclimated slurry, the dechlorination activity of 2- and 3-CP was inhibited in the presence of 20 mg/l of three tested metals. Metals amended to 2- and 3-CP acclimated sediments exhibited inhibition degree in the order of Cd > Cu > Cr, which are different patterns compare to fresh slurry.