A biological process (10) for treating coal and/or a coal derivative includes inoculating a body (16) of the coal and/or the coal derivative in particulate form, with at least one micro-organism. Plant growth is established on the surface of the body (16) by planting crops and/or grass (28) in the body (16). The coal and/or coal derivative in the body (16) is then allowed to degrade, resulting in the production of a humic particulate material.
