Analysis of methanogens adsorption and biogas production characteristics from different coal surfaces

The aim of this study was to examine the biogas production and the adsorption aspect of microorganism from different coals. Coal samples were obtained from Qianqiu mine and Guandi mine. Microbial populations were cultured from the coal mine drainage. After an anaerobic reaction period at about 35 °C, adsorption rate was determined by the spectrophotometer, while a scanning electron microscopy was used to observe the microorganisms on the coal and the headspace methane was analyzed using gas chromatography. Results show that the coal rank and particle size serve as important factors influencing the adsorption of microorganism and biogenic methane production. With decreasing particle size, the Qianqiu coal produced a considerable adsorption rate between 75 and 79%, while the adsorption rate of Guandi coal was between 52 and 74%. Meanwhile, the density of microorganisms from the Qianqiu coal surface demonstrated a higher level of adsorption than that of Guandi coal following the scanning electron microscopy images. Additionally, Qianqiu coal produced a higher level of biogas production (391.766-629.199 μmol/g) than that of Guandi coal (292.835-393.744 μmol/g) and the Qianqiu coal also generated a higher concentration of methane during the incubation. When the adsorption rate decreasing, the biogas production from various pulverized coals appeared to be decreased and demonstrated a positive correlation to the adsorption rate. The results of this study suggest that the adsorption behavior of microorganisms is closely related to the effect of coal biodegradation and contributes to the biogenic methane production potential.