A special charcoal called biochar made from abundant materials such as wood chips, animal manure, agricultural and other natural waste could hold the key to re-claiming polluted brownfield land across the world, according to the Institution of Chemical Engineers (IChemE).
Biochar is a charcoal made from biomass. Charcoal has been known for improving soil fertility and structure. New research is now revealing its potential to control contaminants such as organic pollutants and heavy metals including lead, copper, cadmium and zinc.
Adding biochar has the ability to lock in chemicals such as arsenic for slow release into the soil. A study comparing soil treated with biochar using waste rice straw was able to reduce the movement of heavy metals in soil by up to two-thirds.
Food-chain safety can also be improved. Another study found that biochar, made from green waste compost, could significantly reduce the take-up of heavy metals in ryegrass, which is widely used in pastures for grazing animals.
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