Discipline: Technology and Engineering
Subcategory: Civil/Mechanical/Manufacturing Engineering
Maxwell Fox - Colorado State University
Co-Author(s): Lei Wang and David Dandy, Colorado State University, Fort Collins, CO
Cyanobacteria has shown promise in the biofuels industry as being an alternative to petroleum-based fuels. Harvesting is estimated to account for approximately 20% of the total production cost, which means there is great potential for these processes to be optimized resulting in improved economic feasibility of algal biofuels . Current techniques for harvesting dilute algal solutions include centrifugation and membrane filtration, both of which require high capital investment and have high operational and maintenance costs . Our group’s previous work focused on the development of serpentine micro-channels which integrate inertial migration and Dean Flow to concentrate cyanobacteria particles into an easily located, concentrated stream . For the particle sizes and channel dimensions used, focusing was achieved with flow rates between 200 and 1000 μL/min and recovery efficiencies of 95%-98% were observed throughout this range. Additional advantages include inexpensive production and maintenance costs due to the absence of moving parts, according to existing results from previous studies.
The aim and focus of my work is to devise a way to scale up dilute solution processing with these micro-fluidic devices to a commercial level of 300 L/min. The first step in upscaling was to design a chip with four channels in parallel; this was accomplished by designing a ‘tree branch’ structure that was modelled after the human vascular system using Murray’s Law . Our results showed that these parallel chips do accomplish focusing in all four channels. Moving forward, chips incorporating a first stage consisting of four micro-channels in parallel followed by a second stage of a single micro-channel will be developed. After optimization, the modular nature of the chip should aid in upscaling, and further testing will reveal the maximum attainable output concentration of this filtration device. The multi-pass, high-throughput micro-fluidic device described here shows promise as a low cost first step in the dewatering process, reducing the overall expense of cyanobacteria harvesting and biofuel production. Although this research is focused on cyanobacteria, the device should be easily adaptable to concentrate other forms algal biomass suspensions.
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Funder Acknowledgement(s): This work is supported by National Science Foundation grant number ERFI-1332404.
Faculty Advisor: David Dandy, David.Dandy@colostate.edu