Reduction and biofixation of carbon dioxide in palm oil mill effluent using developed microbial granules containing photosynthetic pigments

The developed microbial granules containing photosynthetic pigments had successfully achieved approximately 18-21% of carbon dioxide (CO₂) removal in POME for one complete SBR cycle. Also, the granules had reached CO₂ removal at 15-29% within 24h and removal of 25% after 5 days. Both results were inconsistent possibly due to the slow mass transfer rate of CO₂ from gas to liquid as well as the simultaneous effect of CO₂ production and respiration among the microbes. Furthermore, results showed the removal of CO₂ from air increases proportionally with the CO₂ removed in liquid. The CO₂ biofixation of granules attained was approximately 0.23g/L/day for a week. Using the regression model, the removal of CO₂ between liquid and gas, CO₂ biofixation rate were highly correlated with the treatment time. A statistically significant relationship was obtained between CO₂ concentration in liquid, biomass productivity and treatment time for the CO₂ biofixation rate of the granules.