Coal mining byproduct effective for land reclamation, study says

A researcher at the University of Alberta in Canada has discovered that nano humus, a substance extracted from coal mine deposits and then crushed to a black, powdery material, is highly effective at helping reclaim the land and water used in mining.

According to Yihan Zhao, nano humus has “outstanding physical and chemical properties” that remove heavy metals from contaminated water and soil. The material is made up of natural organic compounds and it works like a sponge that attaches and holds heavy metals.

In the study, which was part of her PhD in land reclamation and remediation, Zhao tested wastewater containing cadmium — one of the heavy metals most commonly produced by mining — and found that at a high concentration, about 90% of the toxic heavy metal was removed after just 15 minutes. After 24 hours, 93% was removed.

In Zhao’s view, her findings offer the potential option for a low-cost, more efficient way to remediate industrial wastewater and soil affected by resource extraction and manufacturing processes. This is of particular relevance in developing countries, she said.

She also noted that conventional remediation treatments for heavy metals use large amounts of chemicals which, in turn, can produce further contaminants that require treatment. Some remediation methods also require large amounts of electricity or can take days or months to complete.

However, nano humus and similar compounds can be used not only for quicker remediation of contaminants but can also contribute to soil-building by partially or completely replacing the bulkier materials of manure and straw typically used to amend soil.

In a media statement, the researcher said that she would like to partner with Canadian industries in mining reclamation to field test the nano humus.

Zhao believes that moving from lab research to industrial-scale application will help to determine the actual costs and efficacy of using the material under natural environmental conditions.