Effect of environmental factors on the degradation of 2,6-dichlorophenol in soil

Chlorinated phenols (CP) are frequently found as harmful soil contaminants. Depending on the environment, CP may persist for extended periods of time. The influence of environmental factors on the degradation of 2,6-dichlorop henol (2,6-DCP) in unsaturated soil was examined using Ralstonia basilensis RK1 as inoculum for bioaugmentation. The disappearance of 2,6-DCP in soil microcosms was caused by bacterial mineralization. This was proved using U- C-14-labeled 2,6-DCP. After 5 days of incubation, 61 % of the initial activ ity was detected as (CO2)-C-14, while only 20% of the radioactivity remaine d in the soil, and 2,6-DCP was not detected. The relative importance of ind ividual factors and possible two-factor interactions was assessed using a f ractional-factorial experimental design. The following individual factors w ere identified as important: 2,6-DCP concentration, temperature, inoculum s ize, and the presence of an additional substrate. The strongest factorial i nteraction was observed between bacterial inoculation and 2,6-DCP concentra tion. For practical reasons, the influence of oxygen, organic matter, and t he age of the contamination were not included in the factorial design; howe ver, these factors were analyzed separately and found to significantly affe ct the biodegradation of 2,6-DCP. The findings of this study are important for the design of bioremediation techniques as well as the prediction of na tural attenuation.