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Ancient ‘Biochar’ Could Help Environment


MSU AgBioResearch soil contaminant remediation experts Stephen Boyd, Brian Teppen and Hui Li are looking at the use of biochar to help sequester and remove dioxins and other contaminants from hazardous waste sites known as Superfund sites across the United States. It is a new phase of an ongoing $18 million project funded by the National Institutes of Health.

Biochar is the fine, carbon-rich, porous material made from organic matter through a heating process that is more akin to smoldering than burning. It can be created as a biofuel byproduct and as a result of wildfires. It is also being manufactured from various types of agricultural waste such as corn husks, wood and even manure in low-oxygen chambers at temperatures ranging from 300 to 600 degrees F. Different production techniques equate to different end results, providing an added layer of complexity.

Reducing Soil Contaminants

“The bottom line is to use chars or some other sorbent amendment to reduce the bioavailability of chemicals that occur as contaminants in soils and sediments,” Boyd said. “This reduces risks associated with these contaminants and may let us safely relax clean-up criteria. This might allow, for example, more contaminated sites to be remediated using the limited funds available.”

In a separate study, MSU graduate student Cheng-Hua Liu is examining biochar made from bull, dairy cattle and poultry manures produced at 600 degrees F for sequestration of antibiotics. The heat destroys any antibiotics in the manure, which, when later applied to the soil, could immobilize antibiotics already present. It is estimated that about 70 percent of antibiotics produced are used in animal agriculture.

“We believe this is an innovative approach because you’re reducing the antibiotic load to the environment while also dealing with the legacy problems of antibiotics that have been there a while,” he said. “If we are able to generate antibiotic-free, manure-derived biochar and place it in the field to alleviate the presence of legacy antibiotics, we could really be onto something.”

Some Concerns About Biochar

Despite some positive reports, challenges do remain. Use of biochar has had mixed results on agricultural yields. And there is concern over potential pollutants from the production process.

In an eŽffort to learn more about biochar, MSU AgBioResearch and the Environmental Science and Policy Program formed a special team of scientists to study black carbon in the environment. Some studies have shown that about 10 percent of dissolved organic carbon in surface water is from black carbon, and a significant fraction also exists in the soil. In some U.S. regions, burning of crop residue such as sugarcane in the field is still allowed.

In many other parts of the world, this is a regular practice, and some concern has been voiced over potential air pollution. Biochar also comes with high production costs, so benefits must outweigh those.

– excerpted from AgBioResearch, “The Biochar Boon,” Futures (Spring/Summer 2015).

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