Mathematical modeling of competition and coexistence of sulfate-reducing bacteria, acetogens, and methanogens in multispecies biofilms

Abstract

This work presents an integrated mathematical model able to simulate the physical, chemical, and biological processes prevailing in a sulfate-reducing biofilm under dynamic conditions. The model includes sulfate reduction by complete and incomplete sulfate-reducing bacteria (SRB); lactate removal by sulfate reduction and by acetogenic bacteria and acetate consumption via methanogenesis. Numerical integration based on the method of characteristics has been developed. The major problem of sulfate-reducing fixed-growth reactors is the formation of undesired bacterial species, which compete for space and substrate within the biofilm with SRB. The effect of COD/ratio on the reactor performances in terms of bacterial species distribution and substrate diffusion trends in the biofilm has been assessed. The simulation results reveal a stratification of microbial activities in biofilm reflecting the different ecological niches created by substrate gradients.

Keywords:

• Sulfate-reducing biofilms
• Microbial competition
• Mathematical model
• Method of characteristics

Acknowledgments

This research was carried under the framework of the Project: Integrated system to treat buffalo slurry, aimed to recover water and safe energy—STABULUM, funded, in agreement with the Decision of the European Commission No C (2010) 1261, 2 March 2010, by the Agriculture Department of the Campania Region in the context of the Programme of Rural Development 2007–2013, Measure 124, “Cooperation for development of new products, processes and technologies in the agriculture and food sectors.” The authors would like to acknowledge Erasmus Mundus Joint Doctorate Programme ETeCoS³ (Environmental Technologies for Solids, Soils and Sediments) under the EU grant agreement FPA No 2010-0009. Maria Rosaria Mattei is a doctoral research fellow of the ETeCoS³ programme.

Notes

Presented at the 13th International Conference on Environmental Science and Technology (CEST 2013), 5–7 September 2013, Athens, Greece