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Eco-friendly technology for the processing of livestock manure waste with greenhouse gas absorption

L.M. Maksishko

Section: Social ecology

A method of chemical absorption purification of manure biogas from harmful gases including greenhouse ones (carbon dioxide, methane, ammonia and hydrogen sulfide) is proposed, which provides its purification to obtain highcalorie combustible biogas with high (95%) methane content. In the process of biogas purification we obtain mineral fertilizers due to the absorption of harmful gases from biogas: liquid nitrogen fertilizer – ammonia water with the possibility of its concentration, ammonium sulfate and soda as a by-product of biogas purification. Biogas passes through a treatment plant with water, where it is purified from ammonia, carbon dioxide, hydrogen sulfide. Moreover, repeated passage of biogas through water and chemical absorbent during several fermentation cycles, starting with the laying of manure for fermentation, increases the concentration of nutrients in water and chemical absorbents. To implement the tested method it is required a tight connection between the elements of the biogas installation and the device for purification of biogas – the first and second chemical absorbers with a storage tank. Water samples through which purified biogas was passed for 10 days contained 8 times more ammonium (20.8 mg/dm3 ), 2.3 times more free carbon dioxide, compared to water samples with biogas for 5 days, the level of hydrogen sulfide increased 10 to 15.6 times. That is, as the time of biogas passing through the water of the treatment plant increases, the water is saturated with ammonium compounds, which are suitable for soil fertilization. After reaching a nitrogen concentration of 16.4–20.5% in the water of the treatment plant through which the biogas passes, the liquid is taken into airtight containers and used for plant nutrition. For the formation of ammonia water, a quick effect will be achieved if the biogas from the fermentation of chicken manure is passed through the water, since it contains 52 times more ammonium than pork biogas. Between all treatment tanks there are discharge pipes with clamps in case it is necessary to check the composition of biogas during the process. Purification of biogas in the first chemical absorber is carried out by conversion carbon dioxide to soda with 10% aqueous solution of sodium hydroxide. Purification in a second chemical scavenger using concentrated sulfuric acid is performed from ammonia to form ammonium sulfate, which will contain 21% nitrogen and 24% sulfur. In the case of acidic soils

Keywords: biogas, biogas treatment, biomethane, greenhouse gases, chemisorption, pH of fertilizer, useful elements, acid soils

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Article published in number 1 for 2022
DOI: 10.25750/1995-4301-2022-1-205-209