Biochar is the new black

04 October 2021
PhD Student Jonathan Hessner Lindhardt investigates the properties and uses of biochar – a carbon-rich substance made from biowaste, which has huge potential for improving the environment.

For many years, manufacturing companies have used halogenated non-biodegradables for industrial purposes. These substances tend to end up in nature with great negative effect. However, remarkable advances have been made with the development of biochar, which may be very useful in neutralising halogenated substances.

‘We know that biochar has many useful properties, and we believe biochar can be a catalyst for decomposing halogenated compounds, but we do not know exactly how it works, so that is what I am trying to find out’, says Jonathan Hessner Lindhardt, who works at the Department of Plant and Environmental Sciences at the University of Copenhagen.

Biochar is charcoal produced by pyrolysis of biomass in the absence of oxygen, and it can be made from any biological product that has a high concentration of carbon. This makes it interesting in a global perspective, since residual biomass is ubiquitous, and pyrolysis is inexpensive.

Using biochar to purify groundwater

Jonathan Hessner Lindhardt experiments with biochar made from shrimp shells and its effect on brominated substances, which is one of four substances in the group of halogenated substances.

Biochar has numerous uses, but Jonathan Hessner Lindhardt’s research group is looking into two specific ways of using it to purify groundwater. The first is to pump groundwater from a polluted aquifer through pipes into an above ground filter containing the biochar and reductant composite and then back into the aquifer. The second is to pump the composite directly into the polluted subsoil, which can be done safely due to the non-toxic properties of biochar.

‘I know now that it works. The experiments show that biochar made from shrimp shells can work as a catalyst for decomposing brominated compounds. However, we still need to find out exactly how and why’, says Jonathan Hessner Lindhardt, whose PhD thesis is due in 2022.