Changes of Permeability and Porosity of Tiefa Anthracite after Treatment with an Acetogenic Bacterium Clostridium Sp.

Enhancement of coalbed methane (CBM) production by adding microbes or stimulating indigenous microbes within coalbeds is a promising method. Current research focuses on the study of mixed cultures for improving gas production. However, the application of single purified microbes has only attracted limited attention. In the present work, an acetogenic bacterium, Clostridium sp. was used to treat Tiefa anthracite from Liaoning Province, China. During the treatment, the changes of cell concentration and pH in the treatment solution, mineral components, porosity, surface area, surficial morphology, and permeability of the coal were analyzed. The results showed that pH decreased during the treatment of anthracite by the acetogen. The distance of the carbon layers the coal increased, while the number of aromatic layers (Nc), the packing degree (Lc), and elongation (La) decreased after treatment with the bacterium. Furthermore, compared with the raw coal, the permeability and pore volume increased, which might be improved by the further development of macropores. The present work revealed that acetogenic bacteria Clostridium sp. could change the physical properties of Tiefa anthracite by increasing its permeability and porosity. It offers an alternative method to promote in situ coalbed methane development in the future.