The detoxification of Cu(II) by methanogens during the fermentation of environmentally hazardous Solidago canadensis plant

Abstract

Solidago canadensis plants are a promising, cheap and renewable substrate for methane production. In this way, it is possible to solve two global problems: the lack of efficient energy carriers and the disposal of environmentally dangerous plants. In addition, the process of anaerobic fermentation of S. canadensis in the presence of anaerobic microorganisms is promising for the detoxification of heavy metals, in particular Cu²⁺. It was determined that the effective degradation of S. canadensis by the methanogenic microbiome occurs with a high methane yield of up to 40 %. The input of Cu²⁺ inhibited the fermentation process, but despite extremely high concentrations of Cu²⁺ up to 500 mg/L, anaerobic microorganisms adapted and continued to grow and produce methane after complete copper immobilization. It was established that during the fermentation of S. canadensis by the methanogenic microbiome, the input of Cu²⁺ in concentrations 100, 200 and 500 mg/L Cu²⁺ leads to its 100% precipitation within 6, 18 and 24 days, respectively. At 1000 mg/l Cu²⁺ concentration complete inhibition of microbiome growth was observed. Thus, the possibility of effective detoxification of toxic copper simultaneously with methanogenic fermentation of S. canadensis biomass has been experimentally confirmed. The obtained results are promising for the development of new ecological and energy biotechnologies.