Microalgal Biofilm Reactor: Investigation of Microalgal Attachment to Surfaces

One of the major limitations to mass culture of microalgae for fuel or other value-added products is the high energy cost of separating the biomass from the dilute algal suspension. Biofilm reactors can potentially mitigate this problem by maintaining the biomass and media in different phases during growth. The objectives of this study were to develop techniques to investigate the formation of algal biofilms by two species of green algae in sterile and non-sterile conditions. A continuous-flow culture chamber (flow cell) was developed to allow non-destructive imaging of algal films in real time. Using this technique, Scenedesmus obliquus was shown to form films of up to 50 μm in 7 days in both sterile and non-sterile conditions. However, this species did not remain dominant in the biofilm under non-sterile conditions. Films of Chlorella vulgaris remained smaller than 10 μm. Batch techniques indicated that increasing hydrophobicity of the surface has little effect on the initial attachment of these algal species.