The effect of cosubstrates on phenol degradation kinetics

Kinetic parameters (based on the Monod model) for phenol degradation were measured under single and multiple substrate conditions using batch or fed batch reactor (FBR) techniques. The batch reactor was equivalent to the FBR for qm estimation, but gave higher Ks estimates (5.14 ± 7.34, batch vs. 0.63 ± 0.86, mg/l as phenol). qm was significantly higher with single substrate than multiple substrate feed (120.4 ± 53.9 for phenol only vs. 59.5 ± 23.7 for multiple substrates, mg/g-h); an active biomass correction factor based on the fraction of phenol organic carbon in the stock feed reversed this inequality, but the difference (120.4 ± 53.9 for phenol only vs. 202.5 ± 80.7, corrected, for multiple substrates, mg/g-h) remained significant. Ks was independent of feed composition (0.63 ± 0.86 mg/l as phenol). Paired FBR tests were used to minimize changes in sludge condition, and agreed with unpaired tests. Probability distribution analysis showed that qm and Ks data followed log-normal distributions (r2 > 0.90), and is useful for selecting values for design.