Modeling Combined Effects of Temperature and Structure on Competition and Growth of Multispecies Biofilms in Microbioreactors

It is a well-known challenge to simulate competition and growth of multiple microorganisms in microbioreactors because of complex interactions among microorganisms, substrate, operational conditions, and structure. In this paper, we developed a multispecies thermal lattice Boltzmann model with the cellular automata model coupled to it to investigate competitive biofilm formation of two aerobic nitrite and ammonium oxidizers in a microbioreactor. Three configurations of the microbioreactor with two heating blocks were simulated to compare the combined effects of the structure and temperature on biofilm growth, detachment, and competition. The results revealed that the heating block temperatures and locations had lower effects on the biofilm growth rate and pattern than the inlet port temperature. Increasing temperature of inlet 2 has more effects on the biofilm growth than increasing temperatures of the two heating blocks. The percentage of the biofilm-occupied grids increases from 7.9 to 12.1% when the inlet temperature at inlet 2 increases from 10 to 50 degrees C. Two microorganisms showed different rates of responses to changing temperature and structure. The growth of the nitrite oxidizer was about 20% more than that of ammonium oxidizers. This model enables us to understand interactions between individual cells and biofilm communities in the microbioreactor.