Modeling and Monitoring of Microbial Diversity in Ecosystems - Application to Biological Wastewater Treatment

Key microbiological conversion processes do not result from the work of a single bacterial species but are performed by a wide variety of bacteria. Up till now, this microbial diversity is usually not tracked during reactor operation and mostly neglected in mathematical models. Nevertheless, experimental evidence is available that different process conditions may favor the selection of different types of bacteria, modifying the microbial diversity and consequently the behavior of the ecosystem. This contribution assesses microbial diversity in biological wastewater treatment systems by means of two case studies: nitrification and anaerobic digestion, experimental data being provided for the nitrification process. Situation where a toxicant is present is carefully analyzed for anaerobic digestion. In both cases, the potential of process control to optimize microbial populations is discussed and it is highlighted that frequent changing of operating conditions can impact favorably to overall stability of the processes.