Nyuk-Min Chong

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This work established a mathematical model that formulated degrader formation by conversion of indigenous microbial cells. Degrader conversion is attributed to genetic induction whose force is dependent on the strength of acclimating xenobiotic and the amount of indigenous cells. After successful conversion, which requires an amount of time proportionate to(More)
The purpose of this research was to pursuit the quantification of microbial degradation capacity for 2,4-dichlorophenoxyacetic acid (2,4-D) by detecting and quantifying a prominent 2,4-D degradation encoding plasmid. Batch reactor acclimation, de-acclimation, and re-acclimation tests were conducted during which periods the courses of 2,4-D dissipation and(More)
Activated sludge that originated from a biogenic fed-batch reactor under steady-state was re-cultivated with the same biogenic substrates to test the changes in the sludge's performance in acclimation and degradation of a xenobiotic. Re-cultivations with varying biogenic concentrations were conducted at time points ranging from 16 d before to 4 d after the(More)
Continuous-flow chemostats were operated at different mean-cell-residence-times (θc) and influent concentrations of a xenobiotic (2,4-D) and biogenic substrates. Steady state chemostat biomasses' performances in 2,4-D degradation were analyzed with a mathematical model to determine the quantities of degrader the biomasses contained. The qualification for(More)
Activated sludge treatment of a xenobiotic organic compound, much different from treatment of biogenic organics, must be modeled with interactions involving a two-part biomass of degrader and nondegrader, which selectively or competitively grow on a two-part substrate of input xenobiotic and its biogenic metabolites. A xenobiotic treatment model was(More)
Studies were conducted to evaluate the capacities of an activated sludge in degradation process for a xenobiotic. The results showed that during its acclimation to 2,4-D, the sludge sharply accumulated degradation capacities before degradation could proceed at a noticeable rate; moreover, during de-acclimation the sludge gradually lost some capacities in a(More)
Xenobiotic shock experiments were conducted on lab-scale continuous-flow activated sludge systems to examine activated sludge treatment performance and to determine the xenobiotic degrader loss after periods of xenobiotic absence. The systems were operated with normal influent of a xenobiotic and a biogenic substrate until steady state, and were then(More)
The biomass yield of a continuous flow activated sludge system varied when the system treated influent containing different compositions of biogenic and xenobiotic substrates. Both the biogenic substrate and a test xenobiotic 2,4-dichlorophenoxyacetic acid (2,4-D) were degraded at steady-state activated sludge operations. The true yields, determined from(More)
Activated sludge consumes a large amount of energy to degrade a xenobiotic organic compound. By tracking the energy inventory of activated sludge biomass during the sludge's degradation of a xenobiotic, any disadvantageous effect on the sludge's performance caused by energy deficiency can be observed. The purpose of this study was to develop a reliable and(More)
Lab-scale continuous flow activated sludge systems that were acclimated to 2,4-dichlorphenoxyacetic acid (2,4-D) under sole 2,4-D influent and without sludge wastage, were able to maintain successful 2,4-D treatment when both 2,4-D and a biogenic substrate were fed and the systems operated with finite mean cell residence times (theta(c)). When the systems(More)