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The development of carbon dioxide removal methods, coupled with decreased CO 2 emissions, is fundamental to achieving the targets outlined in the Paris Agreement limiting global warming to 1. Here we are investigating the importance of the organic carbon feedstock to support silicate mineral weathering in small-scale flow through bioreactors and subsequent CO 2 sequestration.
Here, we combine two bacteria and two fungi, widely reported for their weathering potential, in simple flow through bioreactors columns consisting of forsterite and widely available, cheap organic carbon sources wheat straw, bio-waste digestate of pig manure and biowaste, and manure compost , over six weeks. Microbial biomass is higher in the straw columns compared to the digestate and manure compost columns, with a phospholipid fatty acid derived total microbial biomass 10 x greater than the other biotic columns.
Scanning Electron Microscopy imaging shows the most extensive colonisation and biofilm formation on the mineral surfaces in the straw columns. The selection of organic carbon sources to support microbial communities in the flow through bioreactors controlls the silicate weathering rates and CO 2 sequestration.
It has been estimated that CO 2 removal needs to reach 0. Silicate weathering buffers atmospheric CO 2 partial pressure, balancing emissions over geologic timescales thereby stabilising the climate to habitable conditions 8 , 9.
