Implications of light attenuation for the upscaling of mixed purple phototrophic bacteria processes
Résumé
Light attenuation in purple phototrophic bacteria (PPB) has been studied. The results show that increased biomass concentrations lead to higher light attenuation, and that PPB absorb both visible and near-infrared wavelengths. Both spectrum fractions were equally absorbed at PPB concentrations above 1 g COD•L-1. A flat plate configuration showed less attenuation than top-illuminated cylindrical reactors, representative of open ponds. Neither a complex wastewater matrix nor the presence of polyhydroxyalkanoates affected light attenuation. The concentration of pigments (e.g. carotenoids and bacteriochlorophyll) had a strong effect, with much higher attenuation in the presence of pigments compared to non-pigmented biomass. In dense outdoor PPB cultures (≥1 g COD•L-1), effective light penetration is only 5 cm. This, together with the increased oxygen diffusion in large open ponds, biases design away from horizontal lagoons, and towards multi-panel systems such as flat plate reactors.
Origine | Fichiers produits par l'(les) auteur(s) |
---|