Effect of glucose as co-metabolism substrate on the biodegradation of dichlorophenols.

In this study, co-metabolism biodegradation of DCPs was investigated, with glucose as co-metabolism substrate and four DCPs including 2,3-dichlorophenol (2,3-DCP), 2,5-dichlorophenol (2,5-DCP), 3,4-dichlorophenol (3,4-DCP) and 3,5-dichlorophenol (3,5-DCP) as target pollutants. The results showed that glucose could accelerate the biodegradation process of DCPs due to the reasons that glucose could enhance the microorganisms' adaptability towards DCPs as a co-metabolism substrate in the activated sludge and speed up the acclimation process of DCPs high-efficiency degradation strains, which indirectly improved the biodegradation rate of DCPs in activated sludge. Through 80 days of acclimatization, the microorganisms were able to degrade 6.5 mg L-1 2,3-DCP, 7.5 mg L-1 2,5-DCP, 6.3 mg L-1 3,4-DCP and 7.2 mg L-1 3,5-DCP in different bioreactors, respectively. With the stepwise improvement of glucose feed concentration, the biodegradation rate of DCPs changed gradually. The glucose influent concentrations of 1000 mg L-1, 1200 mg L-1, 1000 mg L-1 and 1200 mg L-1 were selected as optimal experimental value, respectively. Under these conditions, biodegradation concentrations of 2,3-DCP, 2,5-DCP, 3,4-DCP and 3,5-DCP with the initial concentration of 15 mg L-1 reached up to 11.6 mg L-1, 12.3 mg L-1, 11.5 mg L-1 and 10.6 mg L-1, correspondingly. Combination with DCPs structure and effect of each DCP on microorganisms, results also demonstrated that the meta- and papa-substituted CPs were of greater toxicity than the ortho-substituteds'.