Application of bioenergetic principles to the stoichiometry of biological reactions in wastewater treatment processes

Biological wastewater treatment is performed by microorganisms by means of oxidation-reduction and fermentation reactions that release energy for growth and maintenance. These processes can be represented by stoichiometric reactions developed based on thermodynamic principles. Reactions are dependent on the compounds used as electron donor and acceptor. The overall stoichiometric reactions allow estimations of nutrient requirements, alkalinity/pH changes, biomass and gas production, and yield coefficient. This article described a methodology for stoichiometry calculations using bioenergetic principles, presenting examples with different substrates and electron acceptors.