Feasibility of microbially induced carbonate precipitation through a Chlorella-Sporosaricina co-culture system

Microbially induced carbonate precipitation, an eco-friendly and energy-efficient technology, has attracted many researchers' attention because of its potential use for soil solidification, crack repair and concrete self-repair, etc. In this study, the feasibility of using enhanced co-culture of Chlorella sp. and Sporosaricina pasteurii under mixotrophic conditions to induce carbonate precipitation was investigated. The effects of different growing conditions on microbial growth and their relationship with microbially induced carbonate precipitation were evaluated. The results showed that under optimal growth conditions of algae-bacteria inoculation volume ratio of 3:2 (v/v), initial pH value of 9.0 and glucose concentration of 1 g.L⁻¹, the algae-bacteria co-culture system was able to effectively induce carbonate precipitation and the Chlorella sp. biomass in the co-culture system was significantly improved by 37.74%. The Ca²⁺ rate was reduced by 60.4% in the co-culture system, which was higher than that in the mono-culture system. The calcification rate constant in the co-culture was 0.3514. The crystalline mineral particles were calcite crystals as determined by X-ray diffraction. It was observed through a scanning electron microscope that mineral particles piled up together and some microbial cells were deposited on the crystal surface. These results suggest that microbially induced carbonate precipitation through Chlorella-Sporosaricina co-culture is feasible, but more studies are necessary to understand mechanisms and optimize the process.