Influence of Heavy Metals on the Process of Anaerobic Fermentation of Biomass by the Consortia of Anaerobic Microorganisms

Abstract

Heavy metals released into the environment have a negative impact on the development of living organisms and soil fertility. The use of biomass obtained on such soils as a substrate for biogas production is problematic since heavy metals affect the consortia of microorganisms-decomposers and methane producers, and, consequently, the biogas yield. Therefore, the effect of certain metal ions and their concentrations in the environment on the development of the anaerobicconsortia for biogas production is the topical question. We are aimed to generalize research findings across the influence of heavy metal compounds on the process of anaerobic fermentation of biomass and determination of limiting concentrations for the functioning of the anaerobic consortia. Analysis of the literature has shown that the addition of heavy metal salts to the working medium affects the process of anaerobic fermentation, which depends on the form of the introduced metal, its concentration, the preliminary adaptation of the consortia to the metal. The biogas yield depends on the concentration of the element under study and the presence of other elements in the substrate. It has been established that the allow­able concentrations of metal ions are as follows: for іron – 20 g/l Fe0 or 500 mg/l K2FeO4; for chromium – 50 mg/l Cr3+; for copper – 40 mg/l CuCl2; for zinc – 40 mg/l ZnCl2. The data obtained on the influence of various concentrations of heavy metals on the anaerobic fermentation process will make it possible to model and conduct further studies of the effects of both individual heavy metal ions and their combinations on the biotechnology of processing waste containing such metals.