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This study aimed to investigate the effect of glucose or sucrose as co- substrate on the kinetics of 4-chlorophenol (4-CP) biodegradation by 4-CP-acclimated activated sludge. The performance of 4-CP biodegradation was enhanced in the presence of co-substrate with greater values of zero-order rate constant observed for sucrose compared to glucose at higher 4-CP concentration. The interaction effects of two factors, namely initial 4-CP and co-substrate concentrations ranging from 100-500 mg l-1 and 0-1000 mg l-1, respectively, on the biodegradation kinetics were examined by using response surface methodology (RSM). For glucose, the kinetics was found dependent on the 4-CP initial concentration. The optimised condition for 4-CP biodegradation in the presence of glucose was: 200 mg l-1 4-CP and 750 mg l-1 glucose with rate constant of 7.630 mg l-1 h-1. [ABSTRACT FROM AUTHOR]

The removal of highly toxic phenolic compounds, such as phenol and p-nitrophenol (PNP) from wastewater through biological approach provides a good cleanup strategy in wastewater treatment. It is recognised as an efficient green treatment with relatively low cost in comparison to conventional physicochemical processes. In this present study, activated sludge was acclimated to phenol and PNP, respectively, using sequencing batch reactor (SBR) system. The growth kinetics of both phenol- and PNPacclimated activated sludge were well described by Haldane model. The values of the Haldane kinetic parameters, namely, maximum specific growth rate, μmax, saturation constant, Ks, and inhibition constant, Ki, were found to be 0.4039 and 0.1346 h-1, 5.393 and 110.3 mg l-1, and 550.8 and 63.58 mg l-1, respectively. The smaller ratio of Ks/Ki for phenol degradation compared to that of PNP biodegradation indicates the higher resistance of phenol-acclimated activated sludge to inhibition by its substrate. The pseudo zeroth-order equation was able to describe the phenol degradation kinetics at different initial concentrations. However, the equation was inadequate for the PNP degradation which was attributed to its higher toxicity compared to phenol. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effects of operational factors, namely: 1. type of activated sludge; 2. activated sludge concentration; 3. initial phenol concentration; and 4. addition of sucrose; on the biodegradation of phenol in batch experiments. At various initial phenol concentrations, complete phenol biodegradations with chemical oxygen demand (COD) removal of 95% were achieved by both unacclimated and phenol-acclimated activated sludge. The performance of biodegradation was greatly enhanced, with biodegradation time shortened from 330-1260 to 35-330 min for initial phenol concentrations of 25-250 mg l-1, when the activated sludge was acclimated to the target compound, despite the low acclimation concentration of 50 mg l-1. Phenol biodegradation time was found to decrease with increasing activated sludge concentration and decreasing initial phenol concentration. In the presence of sucrose as co-substrate, biodegradations of phenol by both unacclimated and phenol-acclimated activated sludge were improved. The kinetic data for the biodegradation of phenol was well-fitted into pseudo-first-order model. The values of rate constant of phenol-acclimated activated sludge were found to be higher compared to those of unacclimated activated sludge under all the operational conditions studied. For phenol-acclimated activated sludge, the values of pseudo-first-order rate constant, k, were observed to decrease with increasing concentration of activated sludge and decreasing initial phenol concentration. [ABSTRACT FROM AUTHOR]