Nonconventional treatments of agro-industrial wastes and wastewaters by heterotrophic/mixotrophic cultivations of microalgae and Cyanobacteria

Unlike photoautotrophy, heterotrophy is a mode in which the absence of light, organic carbon dissolved in the culture media are used as substrates for energy production and growth in aerobic using respiration. Mixotrophy is another process of a culture where microalgae combine the two modes (photoautotrophy and heterotrophy). Indeed, during mixotrophy, inorganic carbon (CO2) is fixed by photosynthesis in the presence of light. In contrast, organic carbon is assimilated and metabolized to generate energy and metabolites by aerobic respiration. The purpose of this chapter is to describe the ability of photosynthetic microorganisms to metabolize carbon heterotrophically and mixotrophically in agro-industrial wastes and wastewaters and the potential benefit which presents this combination to the overall economy of production while generating value-added biomolecules with significant industrial interests.