The Coproduction Of H₂-CH₄ By Microbial Degradation Of Pretreated Lignite

In order to investigate the characteristics of coproduction of biogenic gas?H₂-CH₄?from the pretreated lignite,this paper mainly collected in Inner Mongolia Baiyinhua lignite and fresh mine water as experimental materials,and we carried out the experiments of the pretreatment of coal samples and lignite fermentation combined gas production.We measured gas production,gas components,activity of hydrogenase,COD concentration after coproduction of different pretreatment lignite.The coal samples after gas production were tested by XRD and infrared,and the change characteristics of the microcrystalline structure and the functional groups were analyzed.The experimental results show that:?1?The hydrogen production of alkali-treated coal is the best,the total hydrogen production and the content of hydrogen is 10.55 mL g^-1,47.40%;?2?The effect of coproduction of acid treatment and oxidation treatment coal is the best.The total methane production and the percentage of methane of acid-treated coal is 2.34 mL g^-1,23.27%,the oxidized coal is 3.48 mL g^-1,31.45%;?3?The activity regularity of hydrogenase in different coal samples is basically corresponding to the law of gas production.In the process of hydrogen production,the activity of the hydrogenase of the alkali treated coal is the highest,which is 0.99 mL/?mg·min?,while in the process of methane production,the activity of the hydrogenase of the oxidized coal is the highest,which is 0.68 mL/?mg·min?;?4?In the phase of hydrogen production,the COD test rule of different coal samples is opposite to the effect of gas production.The COD value of the alkali treated coal is the lowest,which is 455.15 mg/L,while the COD value of the raw coal is the highest,which is 2192.7 mg/L.In the methane production stage,the COD values of the bacterial liquid corresponding to different coal samples are generally low,and are basically maintained between 20 mg/L⁹0 mg/L;?5?The aromatic carbon lamellar spacing of the pretreated coal is bigger than that of the raw coal,while the stacking degree and the number of the aromatic layers is smaller.The telescopic change of functional groups in coal samples showed that the pretreated coal samples were stronger than raw coal in terms of the stretching vibration of hydroxyl,amino,carboxylic acid or carboxylate,while the stretching vibration of methyl,methylene,aromatics and the out of plane bending vibration of aromatic rings were all reduced.?6?Using the selected acid treatment coal to carry on the comparison experiment of the coproduction and conversion condition finds that under the transformation conditions with variable ventilation phase CO₂ and hydraulic retention time of 3 d,the coproduction of methane with acid treated coal samples is better.Among them,the highest methane yield was 4.73 mL·g^-1 with CO₂ as the gas phase,and the methane production of 3 d for hydraulic retention time is 2.00 mL·g^-1,while with the extension of hydraulic retention time,the effect of gas production is getting worse.The rules of the hydrogenase activity value,the COD value of the broth,the microcrystalline structure of the coal,and the change of the functional group of the coal under different transformation conditions are basically consistent with the rules in the co-production process of the pretreated brown coal.The research provides a theoretical basis for microbial fermentation of lignite.It has great significance for utilization of coal and microorganism to increase production of coal bed biogas and optimizing energy structure in China.