Influence of anaerobic fermentation of organic waste to change the content of biogenic elements in the effluent biogas plant

Abstract

Goal. To establish the influence of anaerobic fermentation of plant and animal origin on changes in the content of biogenic elements in the liquid and solid fractions of effluent after the production of biogas. Methods. Analytical, calculation, mathematical-statistical. Results. It is established that the transformation of organic compounds in anaerobic fermentation process causes an alkaline reaction of biogas effluent. Comparing samples of the liquid fraction (fugate) and the solid fraction (digestat) of waste biogas production from different raw materials (bagasse, corn, and sorghum silage), it is determined that the content of nitrogen and potassium in the samples of discharge exceeds the corresponding figures of digestat, but the phosphorus content is higher in digestat (almost double). As to the content of biogenic elements the effluent after anaerobic fermentation of silo id better than the waste after processing the pulp. Liquid and solid fractions of the waste of biogas plant are enriched with ammonium nitrogen compared with the raw material more than on 40–60% (depending on raw material). Fugate contains less than 5% of solids and a major amount of potassium. Up to 80% of the mass fraction of nitrogen in fugate is in its ammonium form. On the background of low ash content of digestat the content of total carbon is high (over 30%). Conclusions. The studied wastes of biogas plants which work on raw materials of plant and animal origin on agrochemical indicators are not worse than other raw materials and have a high fertilizing potential, especially in acidic soils, because of their alkaline reaction. Waste of biogas plants is characterized by low ash content and high content of total carbon, which confirms their value to potential humus creation ability in soils.