A comparative evaluation of design factors on bubble column operation in photosynthetic biogas upgrading

Studies attempting to optimise photosynthetic biogas upgrading by simultaneous investigation of the bubble column-photobioreactor setup have experienced considerable variability in results and conclusions. To identify sources such variation, this work quantitatively compared seven design factors (superficial gas velocity; liquid flow rate (L/G) ratio; empty bed residence time; inlet pH; alkalinity; temperature; algal concentration) using L16 Taguchi orthogonal array as a screening experiment. Assessments were performed signal noise (S/N) ratio on performance CO2 removal (CO­2 efficiency, absorption rate, overall mass transfer coefficient) O2 stripping (O2 concentration biomethane biomethane). Results showed that pH L/G most critical factors. Temperature times had minimal impact composition. The interactive effect between was impactful, followed effects superficial velocity efficiency. ratio, concentration, (in order impact) caused up 90% variation oxygen content biomethane. However, diminishing role increased. Using only statistically significant main interactions, composition (CO2% O2%) predicted with over 95% confidence through regression equations for 0.2 cm/s.