Comparison and modification of inhibition kinetic models on phenol biodegradation data

Abstract

Organic priority pollutants present an important problem to biological wastetreatment facilities, because they often inhibit the growth of organisms which areresponsible for their degradation. Phenol is considered as one of these organicpriority pollutants by the U.s Environmental Protection Agency (EPA).The purpose of the thesis, was to determine, experimentally, the inhibitioncharacter of phenol and to review and modify the existing inhibition models byusing a microbial culture, dominated by Pseudomonas Putida.In the experimental part of the study, data were obtained to relate thespecific growth rate to substrate concentration, after acclimation of bacteria tophenol, for two different ranges of microorganism concentrations.In the second part of the study, five inhibition mo:iels taken fromliterature sources were applied to the data obtained in the first part of the study.Results showed that the acclimation period was very effective on thebiodegradation kinetics.Finally, three new equations were derived and tested by non-linearregression techniques for correlation of specific growth rate with inhibitorconcentration. Comparison of the fit of the data to total of eight inhibitionequations has shown that it is difficult to choose one single equation whichrepresents best the inhibition kinetics of phenol. Rather, depending on theexperimental conditions and the nature of the microbial population, one or agroup of these equations can be selected to serve as models of the specificinhibition problem, one is dealing with.