Assessments of CO2 biomineralization and its kinetics using indigenous microorganisms derived from landfill cover soil

Abstract

Biomineralization of carbon dioxide into geologically stable carbonate (CaCO3) is associated with a wide range of microorganism in natural environment. Sewage sludge cake generated in municipal wastewater treatment plant is generally mixed with lime, before being disposed into landfill site anticipating effective biomineralization in the cover soil strata and solidification. Objective of the present study was to map the abundance and activity of indigenous microbial population for biomineralization, underneath the landfill cover soil (LFCS) in S landfill site, Korea. CO2 biomineralization microcosm study was conducted with indigenous microorganism isolated from LFCS and was compared with other potential-pure culture strains. To characterize possible relationship between the rate of bacterial growth (biomass production) and CaCO3 precipitation, batch kinetic experiments with live, dead, and inactivated bacteria either in nutrient solution or in inert electrolyte were also performed. Out of different microbial population, isolated from the LFCS, two predominant key species were Bacillus megaterium and Alkaliphilus metalliredigens. Significant CO2 mineralization and increased carbonate precipitates (about 30% higher) were observed with the indigenous microorganism, than its abiotic control. Results suggest that the presence of solidified sewage sludge cake in LFCS can naturally and efficiently mitigate CO2 produced from the landfill.