Elucidating the role of nanoparticles on photosynthetic biogas upgrading: Influence of biogas type, nanoparticle concentration and light source

Three different nanoparticles, namely Fe2O3, carbon coated zero valent iron (CACOI) and SiO2, were added to a mixed microalgae culture in order to improve photosynthetic biogas upgrading. Fe2O3 and CACOI nanoparticles at 10 mg/L supported higher CO2 consumptions compared to their respective controls. The addition of Fe2O3 nanoparticles at 70 mg/L resulted in a 38 % enhanced biomass productivity, and 20 % higher CO2 consumption but delayed exponential growth. The CACOI nanoparticles at 70 mg/L resulted in a shorter lag phase, enhanced CO2 consumption by 13 %, and carbohydrate content enhancement by 64 %, while the addition of SiO2 nano -particles at this concentration induced an enhanced lipid and carbohydrates production by 47 % and 68 %, respectively. Interestingly, UV light exposure reduced the beneficial effects of nanoparticles, although CACOI nanoparticles still supported a shorter lag phase and higher carbohydrates production at 70 mg/L. In brief, CACOI nanoparticles hold an untapped potential to promote the metabolism of microalgae during photosynthetic biogas upgrading.

Automated summary

This study investigated the effects of three different nanoparticles on photosynthetic biogas upgrading. Fe2O3 nanoparticles and CACOI nanoparticles showed improved CO2 consumption, biomass productivity, and carbohydrate content under certain concentrations. SiO2 nanoparticles enhanced lipid and carbohydrate production. However, the beneficial effects of nanoparticles were reduced under UV light exposure.