Effects of the surface physico-chemical properties and the surface textures on the initial colonization and the attached growth in algal biofilm

Algal biofilm reactors represent a promising cultivation system that can economically produce biomass without the need for expensive harvesting operations. A critical component of algal biofilm systems is the material used for attachment. This research reports a comprehensive study of the effects of material surface physico-chemical properties, the surface texture, and their interactions on the initial colonization and the long-term attached growth in algal biofilm systems. A total of 28 materials with a smooth surface were tested for initial cell colonization and it was found that the tetradecane contact angle of the materials had a good correlation with cell attachment. The effects of surface texture were evaluated using mesh materials (nylon, polypropylene, high-density polyethylene, polyester, aluminum, and stainless steel) with openings ranging from 0.05 to 6.40 mm. The mesh materials with an opening of 0.5 mm resulted in the highest attachment. The interaction of surface physico-chemical properties and surface texture, and their co-effects on the cell attachment, was quantitatively described using a second-order polynomial regression. The long-term algal attached growth for the different materials showed a trend similar to that found in initial colonization. Collectively, nylon and polypropylene mesh with 0.50-1.25 mm openings resulted in the best initial colonization and long-term attached growth, with a 28-30 g m(-2) biomass yield and 4.0-4.3 g m(-2) day biomass productivity being achieved on a pilot-scale revolving algal biofilm system.