The system\u2019s first step involves spreading a thin layer of crushed, alkaline rock to the area. This raises the soil\u2019s pH level, which, in turn, accelerates the removal of PFOS from the soil via plants growing\u00a0there.<\/p>\n
The next step is to create \u201cbiochar\u201d \u2014 a specialized form of charcoal \u2014 from the harvested plants, which destroys both PFOS and PFOA chemicals. This is done by heating the plants with either a large, stationary machine or a smaller, mobile\u00a0unit.<\/p>\n
Researchers estimate that remediation using this new model costs $1,460 per hectare. Since the process would be repeated each year for up to 20 years, the total cost would be just over $29,000 per hectare \u2014 which includes compensation for the farmer\u2019s lost income during\u00a0treatment.<\/p>\n
The system also has the added benefit of removing carbon dioxide \u2014 a greenhouse gas and main contributor to climate change \u2014 via enhanced weathering of the crushed rock applied to the soil and biochar generated from biomass. At a national scale, the system could remove 10.5 million metric tons of carbon dioxide per year, the researchers\u00a0estimate.<\/p>\n
\u201cThis is a real pathway to actually give farmers in this situation some agency over their land and leave the soil in better condition than it was before,\u201d Thompson\u00a0said.<\/p>\n