| Summary: | 碩士 === 大葉大學 === 環境工程學系碩士班 === 94 === This study was to investigate the performance of a continuous activated sludge for a persistent xenobiotic when the sludge was subjected to periodic loadings of the xenobiotic. The activated sludge was fed with the xenobiotic 2,4-D and sucrose until steady states, and 2,4-D was removed for periods of time (called down-time DT), before square shocks of 2,4-D were re-applied. Operation conditions for the activated sludge were: fixed hydraulic residence time of 8 hours, varied mean cell residence times (θc) of 8 and 14 day, and varied lengths of DT. The results showed that: (1) For DT up to approximately 1/2θc, the activated sludge was able to recover after the shocks; (2) the activated sludge failed at DT of 8 days and 10 days, for θc of 8 days and 14 days, respectively; (3) the retardation of the sludge ability to re-degrade 2,4-D can be mathematically modeled as exponential decay. In addition to the loss by sludge wastage, a de-acclimation rate of 0.288 mg-SS/l-d was found, while a transfer gain rate was shadowed by the loss.
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