Study On Co-production Of High Humic Acid Organic Fertilizer By Lignite Biomethane Gasification

In order to improve the conversion of lignite into biogas and expand the coal-type natural gas coal resources,this study takes Inner Mongolia lignite as the main research object,and regulates its substrate and additional substances to more effectively transform and utilize lignite resources.Firstly,started from activated sludge,used lignite as the carbon source,domesticated the inoculum capable of decomposing lignite,and selectively cultured the inoculum by adding different concentrations of rare earth compounds,then analyzed the changes of alkalinity,COD concentration,coenzyme F₄₂₀ molar concentration and gas production during inoculum acclimation.The results showed that at 50?culture temperature,the daily feed volume was 250mesh lignite 1g,then domesticated the inoculum for 30 days,after adding 0.25 g/L CeCl₃,the highest concentration of coenzyme F₄₂₀ was 1.400×10^-3 mmol/g on the 21st day,the cumulative gas production was 250.33 mL,the COD removal rate reached 81.56%,and the alkalinity increased by 49.72%;when added 0.25 g/L LaCl₃,the highest concentration of coenzyme F₄₂₀was 1.479×10^-3 mmol/g on the 27th day,the cumulative gas production was 248.53 mL,and the alkalinity increased by 52.68%,all were higher than the blank control group without adding rare earth compounds.It is revealed that the addition of rare earth compound acclimated inoculum can help to enrich anaerobic microorganisms,especially methanogens,the TS and VS values of inoculum activated sludge increased after acclimation,it indicated that the inoculum activated sludge can promote to degrade lignite to produce methane after acclimation.Secondly,the domesticated inoculum was used to carry out the effect of humic acid precursor material lignin on the bio-methanation utilization of lignite,and the lignite bio-methanation system with different concentrations of lignin was tested to analyze the pH value during the fermentation process.VFA concentration,daily gas production and total gas production.The results showed that,the humic acid precursor substance lignin inhibited methanation of lignite,the total gas production of the lignite control fermentation group without lignin added was 911.00 mL,after 1000 mg/L lignin added,the total gas production was 718.00mL,during the methanation of lignite,the fixed carbon and volatile matter as carbon sources were used by the microbial flora in the process of methanogenesis.Thirdly,the effect of humic acid degradation product benzyl alcohol,the main component of lignite,on the bio-methanation utilization of lignite was studied.The lignite bio-methanation reaction system was added with different concentrations of benzyl alcohol to analyze the changes of pH value,alkalinity,coenzyme F₄₂₀,VFA concentration,daily gas production and total gas production during fermentation.The results showed that the total gas production of the lignite fermentation group without benzyl alcohol was 157.70 mL,and the highest concentration of coenzyme F₄₂₀ reached the highest value of 1.019×10^-3 mmol/g at the 6th day,the total amount of 2000 mg/L benzyl alcohol added to the lignite fermentation group.The gas production was181.13 mL,and the highest concentration of coenzyme F₄₂₀ reached the highest value of1.690×10^-3 mmol/g on the 6th day,suggesting that the humic acid degradation product benzyl alcohol promoted the methanation of lignite,The microbial flora of the fermentation group added with 2000 mg/L benzyl alcohol was more active.Finaly,the purpose of this study was to study the effect of adding lignite on the spectral properties of dissolved organic matter?DOM?in sheep manure organic fertilizer,and provide a basis for the evaluation of the maturity of high humic acid organic fertilizer.Inner Mongolia brown coal and sheep manure were used as raw materials,10%lignite was added to ferment organic fertilizer of sheep manure,and the DOM extracted from organic fertilizer samples at different stages was analyzed by UV-visible spectrum analysis,fluorescence spectrum analysis and Fourier transform infrared spectroscopy.Ultraviolet-visible absorption spectroscopy analysis showed that the E₄₆₅/E₆₆₅ value of organic fertilizer samples decreased first and then increased with the fermentation of organic fertilizer.From 9.1104 at the beginning of organic fertilizer to a minimum of 4.6477,and then to 5.3901 at the end of organic fertilizer,A₁ showed a decrease and then increased,and both A₂ and A₃ showed a trend of increasing first and then decreasing,and the peak appeared at 12 d.Synchronous fluorescence spectroscopy showed that the ratio of fluorescence peak intensity(I₄₇₀/I₄₃₅)increased from 0.4528 starting from organic fertilizer to0.6552 at the end of organic fertilizer,A_HLR/A_FLR showed an upward trend,rising from 0.6739for organic fertilizer to 1.0408 for organic fertilizer.After 18 d of organic fertilizer fermentation,the fluorescence intensity of the organic fertilizer after fermentation was lower than that of the organic fertilizer at the beginning,and the relative fluorescence intensity of the 10%lignite-added sheep manure organic fertilizer was significantly higher than that of the un-added lignite.Fourier transform infrared spectroscopy showed that carbohydrates,polysaccharides and proteins in DOM were gradually decomposed during the fermentation of organic fertilizer for 18 d,while the content of carboxyl groups and benzene ring-containing substances increased significantly.With the progress of organic manure,the non-humus substances in DOM are converted into humus-like substances,the degree of polymerization or aggregation of unsaturated structures becomes larger,and the stability increases.The addition of lignite can effectively promote the decomposition of lignin substances.Improve the degree of aromatization of DOM and accelerate the maturity of organic fertilizer.