V.A. Vavilin, L.Y. Lokshina. Carbon and hydrogen dynamic isotope equations are used to describe the dominant processes of waste biodegradation: Effect of aeration in methanogenic phase of the landfill // Waste Management. 2023. Vol. 166

Abstract. The sequence of microbiological processes occurring during the decomposition of fresh and old organic wastes from landfills is analyzed using the developed dynamic models, which are verified on the basis of experimental data previously obtained in anaerobic and aerobic laboratory reactors. The models are based on the material balances of the heavy and light isotopes of carbon and hydrogen during the biodegradation of cellulosic waste as a relatively poorly degradable substrate. According to the models, under anaerobic conditions, dissolved carbon dioxide is a substrate for hydrogenotrophic methanogenesis, which leads to an increase in the isotope signature of carbon in carbon dioxide and its subsequent stabilization. After the introduction of aeration, methane production ceases, and from that time on, carbon dioxide remains only a product of cellulose and acetate oxidation, which causes a significant decrease in the isotopic signature of carbon in carbon dioxide. The dynamics of the deuterium content in the leachate water is described as a consequence of the rate of its entry into and exit from the two (upper and lower) compartments of the vertical reactors, as well as the rates of its consumption and formation during microbiological reactions. According to the models, in the anaerobic case, the water is first enriched with deuterium due to acidogenesis and syntrophic acetate oxidation and then diluted with deuterium-depleted water, which is continuously fed to the top of the reactors. In the aerobic case, a similar dynamic is simulated.