Available methane from anthracite by combining coal seam microflora andH₂O₂pretreatment

Abstract

Summary The conversion of coal to methane by anaerobic microorganisms is an efficient, clean, and green way to utilize coal. However, methane production is relatively low due to the low bioavailability of coal. H2O2 has been demonstrated to increase methane production by transferring coal to liquid organics. Little is known about the bioavailability of residual coal after H2O2 pretreatment. Here, H2O2 was employed to pretreat anthracite, and the potential of residual coal to produce methane was analyzed. The optimum conditions for pretreatment were 30% H2O2 for 12 hours when the methane production reached 254.97 μmol/g coal, increased by 24.98% compared with that in unpretreated coal. The results of FTIR showed that the substitutions of aromatics, alkanes rings, aliphatics, and even C=C structure in coal were depolymerized and oxygen‐containing functional groups were generated after pretreatment with H2O2. The oxygen‐containing functional groups were further degraded by anaerobic microflora. The XRD results showed that the crystal structure of coal decreased after pretreatment with H2O2 following 27 days of cultivation. These results suggested that H2O2 pretreatment mainly altered coal by increasing the oxygen‐containing functional groups and decreasing the crystal structure of coal to facilitate coal biodegradation and enhance biomethane production. The effect of H2O2 on the production of biomethane was not only to produce easily degradable organics, but also to change the coal structure and promote the degradation of residual coal. Therefore, the enhancement of biomethane production by H2O2 pretreatment on surface bioconversion and underground coalbed methane mining should take the increase methane yield from residual coal into account.

Selective trace elements significantly enhanced methane production in coal bed methane systems by stimulating microbial activity

“…Nutrient additions often resemble those of selective growth media used to enrich members of anaerobic heterotrophic microorganisms, and previously tested nutrients include various dissolved complex carbon substrates, nitrogen source, phosphate, vitamins, trace elements (TE), macro minerals ( 5 , 8 , 19 , 21 , 23 , 29 , 33 , 41 – 43 ) and methanogenic substrate amendments in situ and in laboratory ( 2 , 44 ). In addition, the effects of physicochemical parameters ( 2 , 45 , 46 ) and the physical connectivity of coal, specifically, surface area enhancement for gas adsorption, have been reported ( 2 , 47 – 50 ). Other studies aimed to enhance methane production by providing complex nutrient sources (e.g., yeast extract, trypticase peptone, algal biomass, rice straw, emulsified nutrient solutions) ( 18 , 36 , 51 – 55 ) and bioaugmentation ( 19 , 20 , 56 ).…”