Microalgae recovery by microflotation for biofuel production using metallic coagulants

Abstract

Background: Harvesting algal biomass is an important unit operation in the production of biofuel from algae. However, many of the known techniques available for harvesting and dewatering microalgal biomass are energy intensive and in some cases intrusive and inefficient. Here we show that microflotation mediated by fluidic oscillation is an approach that differs from dissolved air flotation by the nonintrusive laminar flow approach, as well as low energy consumptions, and is also different from dispersed air flotation by the method of bubble generation. Results and discussion: Using three metallic coagulant types, recovery efficiencies of 99.2, 98.1 and 95.2% were obtained for ferric chloride, ferric sulfate and aluminum sulfate, respectively. The benchmarks in the literature for dissolved air flotation are 40–98%. Conclusion: Biofuel production from microalgae can be facilitated by the improvement of a key unit operation such as harvesting and dewatering. The study outcome strongly recommends the technique as a technology for microalgal harvesting.

Financial disclosure

WB Zimmerman would like to acknowledge support from the Concept Fund of Yorkshire Forward and the EPSRC (grant number EP/I019790/1). WB Zimmerman would like to acknowledge the Royal Society for a Brian Mercer Innovation award and the Royal Academy of Engineering for an industrial secondment with AECOM Design Build. J Hanotu would like to thank the University of Sheffield for a doctoral scholarship. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.