Effect of interspecies interactions on population dynamics in a chemostat as related to bacterial supplementation processes

Interspecies interactions occur in all biological wastewater treatment processes because they rely on mixed cultures. The effect that these interactions have on process performance is difficult to determine, especially in real treatment processes, due to the complexity of the naturally occurring cultures. For this reason a simple two-membered co-culture was used in this research to study the effect that interspecies interactions can play in determining population dynamics and how this can effect treatment performance.;The techniques used in this study differ from those used by others in that a kinetics based approach was used. The organisms growing in mixed culture were tested for changes in growth kinetics from that determined in pure culture. To measure the mixed culture kinetics a procedure was developed for estimating the mass of a given species in a mixed culture. The pure and mixed culture kinetic parameters developed from batch culture studies were used to calibrate mathematical models for the simulation of population dynamics in a chemostat. The simulation results were compared to experimental data. Although slight improvements were achieved through the use of mixed culture kinetics, they were limited in scope. The improvements appear to be limited due to the simplicity of the method. Therefore it appears that the additional work required to develop the mixed culture kinetics may not be justified at this time.;Recommendations are made for future research to be performed using improved experimental techniques and more complex model formulations. It is anticipated that given the recommended changes, the utility of looking at kinetic parameters in mixed culture as initiated in this research will improve our understanding of mixed culture systems and our ability to model them.