Multifunctional Thermosynechococcus sp. CL-1 cultivation in swine wastewater for nutrients utilization, CO2 fixation, and C-phycocyanin production

Abstract

BackgroundCombination of the CO2 fixation and wastewater treatment process can be simultaneously and efficiently conducted using cultivation of photosynthetic microorganisms along with generation of byproducts as the alternative benefit. MethodIn this study, a cyanobacterium, Thermosynechococcus sp. CL-1 (TCL-1), has been cultivated in unsterilized swine wastewater for assessment on nutrients (N and P) removal, CO2 fixation rate, and accumulation of C-phycocyanin. Experiment was conducted using a flat panel photobioreactor and under supply of various light intensities of 500-2,000 µE/m2/s. Significant findingsThe presence of ammonium and phosphate in the swine wastewater were favorable to support the growth of TCL-1. TCL-1 eliminated almost all the ammonium during 8 h of experimental test under illumination of higher light intensity (1,000 or 2,000 µE/m2/s). Similarly, compared to other tested light intensities, 2,000 µE/m2/s resulted in greater phosphate utilization. However, 500 µE/m2/s light intensity indicated a higher total phosphorus utilization. Besides, addition of dissolved inorganic carbon (DIC) in the swine wastewater resulted the highest CO2 fixation rate of 145.1±12.1 mg/L/h. C-phycocyanin as a valuable pigment compound was accumulated by TCL-1 with concentration of 4.9 %dwc, productivity of 6.46±0.7 mg/L/h, and in the purity index range of 0.79-0.86.