Abstract
Stable structure of xenobiotic requires a large amount of energy for the microorganisms to metabolize. In addition to the general hard-to-treat nature of a xenobiotic, the energy expense in breaking xenobiotic structure may add to the difficulty of xenobiotic degradation. This study was to determine the detail profiles of energy contents in activated sludge cells during the cells’ degradation of a model xenobiotic compound 2,4-dichlorophenoxyacetic acid (2,4-D). Energy content in sludge cells was measured as Adenosine Triphosphate (ATP). Activated sludge degradation reactions of 2,4-D were performed with the sole feed of 2,4-D, and sucrose and/or peptone added to the 2,4-D degradation reactions to serve as external energy supply to the metabolism of the xenobiotic. Measurement results show that ATP content per unit mass of sludge biomass was lowered after sludge had degraded 2,4-D. Amount of sludge grown was inevitably lowered due to an energy deficit after 2,4-D catabolism. Biogenic addition indeed increased the average ATP content and yield higher cell mass. The time courses of 2,4-D degradation, cell mass growth, and ATP contained in activated sludge, are presented in this paper with discussion pertaining to the science of xenobiotic degradation and also applicability of ATP enrichment method to xenobiotic treatment bioprocess.
