Production and Utilization of Biochar From Organic Wastes for Pollutant Control on Contaminated Sites

Biochar is the product of heating carbon-rich biomass under low and controlled oxygen conditions. A variety of organic materials such as logs, agricultural residues, waste biomass, and sewage-sludge can be used as feedstock for biochar production. Typical applications are use as agricultural soil amendments to improve soil physical properties, soil fertility, and crop yields. Another use is as an in situ sorbent for soil contaminants. The variable physical and chemical properties of biochar may mobilize and immobilize a variety of soil contaminants such as heavy metals and organic pollutants by direct and indirect means including sorption, ion exchange and precipitation mechanisms, pH change, and manipulation of redox balance. Biochar also influences the rate of degradation of organic pollutants by altering microbial activities in many ways. These characteristics make it possible to develop biochar products designed for site-specific conditions that are highly cost-effective in situ techniques for minimizing risks from exposure to a variety of soil contaminants.