Biogenic methane generation from Vietnamese coal after pretreatment with hydrogen peroxide

Abstract

The application of coal as a methanogenic substrate is limited due to its recalcitrant nature, thus, requiring pretreatment for increasing bioavailability of coal. This paper describes the pretreatment of Vietnamese coal from the Red River Basin. The coal sample was treated with 3% (vol/vol) hydrogen peroxide, which resulted in 45.4% (weight %) solubilization of coal and release of various organics into the liquid phase. This dissolved fraction was analyzed for total dissolved organic carbon, Fourier transform infrared spectroscopy, high-performance size exclusion chromatography, and high-performance liquid chromatography. The detailed analytical investigations revealed the presence of aliphatics and aromatics hydrocarbons in the liquid phase. Short-chain organic acids, including oxalic, citric, malic, malonic, formic, and acetic acids were also observed. The dissolved fraction was subjected to methanogenesis. Methane generation achieved the peak at 218.5 μmol/g coal after 500 days of incubation. The effect of the pretreatment process on inorganic matter of the residual coal samples was also assessed using inductively coupled plasma mass spectrometry. The pretreatment caused a reduction in metal content of the residual coal sample. The findings of the paper can be prospected as a feasibility study of methane production from Vietnamese coal after its pretreatment using hydrogen peroxide.