Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article


Master of Engineering Science


Chemical and Biochemical Engineering


Briens, Cedric L.

2nd Supervisor

Briens, Lauren A.



Biochar can be an effective soil amendment, but concerns are soil contamination and dust emissions. This thesis developed various post-pyrolysis washing solutions to alleviate these concerns. Washing can reduce biochar hydrophobicity, improve its stability and adsorption properties and remove organic, inorganic, and PAH contaminants. The most effective wash was used to facilitate biochar granulation. Biochars from two different feedstocks were tested in a drum granulator with molasses binder. Washing biochar significantly increased the yield of optimally sized granules. Granules from washed biochar were dense, robust and free-flowing. The research showed how washing improved various biochar powders in terms of their chemical characteristics and, through granulation testing, their physical characteristics.

Summary for Lay Audience

Biochar is known as the solid product produced by the pyrolysis of biomass. A pyrolysis reaction is a thermal decomposition of organic waste material heated in the absence of oxygen and produces three main products. Bio-oil, biochar and various gasses are produced during a pyrolysis reaction. Biochar is a stable carbon form of the original biomass material. Numerous studies have concluded that biochar improves soil fertility and removes carbon from the atmosphere.

However, there have been ongoing issues with spreading and applying biochars to soil. These concerns have raised awareness in needing to minimize dust emissions generated by spreading equipment. One proven method is to granulate biochar using various binder solutions to form small granules and spread them. While these granules minimize dust generation, they are still not deemed robust compared to conventional fertilizers used in agriculture.

A simple washing operation is proposed to decrease biochar hydrophobicity and allow it to retain water. In reducing biochar hydrophobicity, other characteristics can be improved, such as stability, adsorption capacity, and the removal of any harmful organic or inorganic contaminants that pose dangers to soil stability. This will ultimately result in biochar with fewer fine particles minimizing dust created during spreading.

Washing biochar is a cost-effective solution to turn it into an effective soil amendment that farmers can accept. Widespread use of biochar as a soil amendment will remove large amounts of carbon from the atmosphere.