Modelling the pH dependence of the kinetics of aerobic p-nitrophenol biodegradation

• Published in: Journal of hazardous materials Vol. 186; no. 2-3; pp. 1947 - 1953
• Main Authors: Carrera, Julián, Martín-Hernández, Mariángel, Suárez-Ojeda, María Eugenia, Pérez, Julio
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 28.02.2011; Elsevier
• Subjects: acid-base balance; Acid–base equilibrium; activated sludge; Aerobiosis; Algorithms; Applied sciences; Arrays; Biodegradation; Biodegradation, Environmental; Biomass; Calibration; Coefficients; Exact sciences and technology; General purification processes; Haldane model; Half-saturation coefficient; Hydrogen-Ion Concentration; Hypotheses; Inhibitors; Kinetics; Mathematical models; Nitrophenols - chemistry; Nonionised substrate; Nonlinear Dynamics; Norms; oxygen; Oxygen - analysis; Oxygen - chemistry; p-nitrophenol; Pollution; prediction; Sewage - analysis; Solutions; Substrate inhibition; Substrate inhibition constant; Wastewaters; Water; Water treatment and pollution; Haldane model; Acid–base equilibrium; Nonionised substrate; Half-saturation coefficient; Substrate inhibition constant; Biodegradation; Activated sludge; Pollutant behavior; Saturation; Prediction; Aerobe; Modeling; Acid-base equilibrium; Uptake; Biological purification; Kinetic model; Batchwise; pH; Kinetics; Kinetic parameter; Waste water purification
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2010.12.096

There are a number of publications in the literature that might indicate a connection between pH and the kinetics of the aerobic p-nitrophenol (PNP) biodegradation. In this study two hypotheses were postulated to elucidate the kinetics dependence on pH: (i) the substrate inhibition does not depend on the pH value, therefore the half-saturation coefficient and the substrate inhibition constant will be the same at any pH and (ii) the substrate inhibition depends on the pH value, therefore the half-saturation coefficient and the substrate inhibition constant will have a different value depending on the pH. A PNP-degrading activated sludge was used to carry out three batch respirometric experiments at different pH values: 6.5±0.1, 7.0±0.1, 8.0±0.1. The ability to describe the experimental results with the kinetic models derived from both postulated hypotheses was quantitatively evaluated through the norm of the prediction error array. The time course of specific oxygen uptake rate and PNP concentration was satisfactorily described by a Haldane kinetics that includes the pH effect, based on the PNP acid–base equilibrium, on the kinetic parameters. The results suggest that the nonionised form of PNP is the real substrate and also the inhibitor of the aerobic PNP biodegradation.