RESUMO
Indigenous microbes from the sediments, whether contaminated with hexachlorobenzene (HCB) or not, could dechlorinate HCB effectively without any acclimation and supplemental nourishment. Temperature seriously affected the HCB-dechlorination: within the measured 15-45 degrees C span, the optimum range was between 30 and 35 degrees C. Sulfate-reducing bacteria (SRB), denitrifiers, and acetogens might not be directly involved in the HCB dechlorination. However, the SRB retarded subsequent dechlorination of pentachlorobenzene to tetra- and trichlorobenzenes. Some vancomycin-resistant gram-positive bacteria and methanogens were most likely to be the HCB-dechlorinators. The dechlorination followed the Michaelis-Menten behavior with the k'(m) and K(HCB) between 0.45-0.73 mg L(-1)day(-1) and 3.2-17.2 mg L(-1), respectively. These findings suggest a potential HCB treatment and cleanup for wastewater and contaminated site.
