Integrated hollow fiber membranes for gas delivery into optical waveguide based photobioreactors

Abstract

Compact algal reactors are presented with: (1) closely stacked layers of waveguides to decrease light-path to enable larger optimal light-zones; (2) waveguides containing scatterers to uniformly distribute light; and (3) hollow fiber membranes to reduce energy required for gas transfer. The reactors are optimized by characterizing the aeration of different gases through hollow fiber membranes and characterizing light intensities at different culture densities. Close to 65% improvement in plateau peak productivities was achieved under low light-intensity growth experiments while maintaining 90% average/peak productivity output during 7-h light cycles. With associated mixing costs of ∼ 1 mW/L, several magnitudes smaller than closed photobioreactors, a twofold increase is realized in growth ramp rates with carbonated gas streams under high light intensities, and close to 20% output improvement across light intensities in reactors loaded with high density cultures.

Debottlenecking Thermophilic Cyanobacteria Cultivation and Harvesting through the Application of Inner-Light Photobioreactor and Chitosan

“…This resulted in a sufficient illumination of the cells at the bottom of the reactor and a 56% increase in Chlorella production. Ahsan et al [ 11 ] improved a photosynthetic microbial photobioreactor with a built-in V-groove optical panel machined from transparent plexiglass, in which light is shone through the top of the reactor into a V-shaped trough. It is then transmitted laterally to the bacterial cells, which also improves the biomass yield.…”

Preparation and performance of biofouling resistant PAN/chitosan hollow fiber membranes

“…However, these membranes are severely affected by membrane fouling due to its poor hydrophilicity and biocompatibility. It decreases the water flux and increase the filtration cost (Li et al 2014a, b;Booshehri et al 2013;Ahsan et al 2015;Saufi and Ismail 2002;Ren and McCutcheon 2015;Oh et al 2001).…”

Breathable waveguides for combined light and CO2 delivery to microalgae

“…Waveguiding distributes light through large volumes of culture, and shifts operational cost (pumping) to capital cost (material). Recently, reactors using planar waveguides have demonstrated improved light distribution, photosynthetic productivity, cell density, and modular scalability (Ahsan et al, 2015;Pierobon et al, 2014). However, waveguides developed to date occupy significant reactor volumes (5 -33%), limiting volumetric productivity (Ahsan et al, 2015;Dye et al, 2011;Xue et al, 2013).…”

“…Recently, reactors using planar waveguides have demonstrated improved light distribution, photosynthetic productivity, cell density, and modular scalability (Ahsan et al, 2015;Pierobon et al, 2014). However, waveguides developed to date occupy significant reactor volumes (5 -33%), limiting volumetric productivity (Ahsan et al, 2015;Dye et al, 2011;Xue et al, 2013). Furthermore, all waveguide reactor strategies reported to-date are impermeable, choking cultures of vital CO2.…”

“…Alternative aeration architectures based on nanoporous membrane contactors achieve single-phase gasto-liquid mass transfer, and cost-effective CO2 delivery and utilization (Bilad et al, 2014;Gabelman and Hwang, 1999;Markov et al, 1995). Recently, hollow fiber membrane contactors have demonstrated enhanced mass transfer of CO2 to cells in photobioreactors (Ahsan et al, 2015;Kalontarov et al, 2014;Kim et al, 2011). With high density cultures, however, a high density of hollow fibers is required to avoid CO2 limitations (Ahsan et al, 2015;Kalontarov et al, 2014).…”