Anaerobic biodegradation characteristics of three estrogens

摘要

The anaerobic degradation characteristics of three estrogens (E1, E2 and EE2) under the single and combined conditions were investigated by the intermittent anaerobic degradation experiments, and the influence of the initial estrogen and sludge concentrations on the biodegradation process were also studied. The results indicated that the anaerobic degradation process of three estrogens included the fast degradation stage and the slow degradation stage, which all followed the first order degradation kinetics. In the single degradation experiments, at the fast degradation stage, the degradation rate constant of E2 was the largest in the three estrogens, which was 2 and 5.17 times of E1 and EE2, respectively; however, at the slow degradation stage, EE2 almost could not be biodegraded, and the degradation rate constant of E and E2 was 0.18 and 0.34 times of that at fast degradation stage, respectively. Meanwhile, it was found that E1 was accumulated in the degradation process of E2, which indicated that E1 was a main intermediate product of the E2 anaerobic biodegradation. In the combined degradation experiments, the degradation rate constants of estrogens had the order of E1>E2> EE2, and the contribution of the fast degradation stage was crucial to the removal of estrogens under anaerobic conditions. The degradation rate constant of estrogens decreased linearly with the increase of the initial estrogen concentrations, and increased linearly with the increase of the sludge concentrations, which indicated that the higher sludge concentrations benefited the removal of estrogen under anaerobic conditions in the practical project.