Innovative algae dewatering technology

Abstract

This paper describes a novel technology for dewatering of bio materials, such as algae, for biofuel production and other applications. This hydrodynamic separation (HDS) technology uses customized fluid flow patterns to focus suspended particulates into a well-defined band near a side wall of a curved channel, and where they can be separated off with a suitably designed flow splitter. The novel and innovative capability of this system is its ability to separate particles of any density, including neutrally buoyant particles such as algae and other biological and/or organic matter, from a liquid without the use of a physical barrier. Advantages of this technology over conventional practice include: small foot print, low energy requirement, rapid process, and continuous flow operation. We explored the dewatering of different algae species including Spirulina, Chlorella Vulgaris, and S. dimorphus. Larger algae or algae that naturally form larger aggregates can be concentrated very efficiently without the use of any added chemicals and harvesting efficiencies up to 97% have been demonstrated. This makes HDS very attractive for the dewatering of algae from concentrations typical for open ponds (<0.1%) to above 1 % dry weight, where the addition of flocculants, which is needed for most other dewatering technologies, is costly and may add constraints to the reuse of the clean stream.