Anaerobic digestion, whose final products are methane and carbon dioxide, ensures energy flow and circulation of matter in ecosystems. This naturally occurring process is used for the production of renewable energy from biomass. Lactate, a common product of acidic fermentation, is a key intermediate in anaerobic digestion of biomass in the environment and biogas plants. Effective utilization of lactate has been observed in many experimental approaches used to study anaerobic digestion. Interestingly, anaerobic lactate oxidation and lactate oxidizers as a physiological group in methane-yielding microbial communities have not received enough attention in the context of the acetogenic step of anaerobic digestion. This study focuses on metabolic transformation of lactate during the acetogenic and methanogenic steps of anaerobic digestion in methane-yielding bioreactors. Methane-yielding microbial communities instead of pure cultures of acetate producers were used to process artificial lactate-rich media to methane and carbon dioxide in up-flow anaerobic sludge blanket reactors. The media imitated the mixture of acidic products found in anaerobic environments/digesters where lactate fermentation dominates in acidogenesis. Effective utilization of lactate and biogas production was observed. 16S rRNA profiling was used to examine the selected methane-yielding communities. Among Archaea present in the bioreactors, the order Methanosarcinales predominated. The acetoclastic pathway of methane formation was further confirmed by analysis of the stable carbon isotope composition of methane and carbon dioxide. The domain Bacteria was represented by Bacteroidetes, Firmicutes, Proteobacteria, Synergistetes, Actinobacteria, Spirochaetes, Tenericutes, Caldithrix, Verrucomicrobia, Thermotogae, Chloroflexi, Nitrospirae, and Cyanobacteria. Available genome sequences of species and/or genera identified in the microbial communities were searched for genes encoding the lactate-oxidizing metabolic machinery homologous to those of Acetobacterium woodii and Desulfovibrio vulgaris. Furthermore, genes for enzymes of the reductive acetyl-CoA pathway were present in the microbial communities. The results indicate that lactate is oxidized mainly to acetate during the acetogenic step of AD and this comprises the acetotrophic pathway of methanogenesis. The genes for lactate utilization under anaerobic conditions are widespread in the domain Bacteria. Lactate oxidation to the substrates for methanogens is the most energetically attractive process in comparison to butyrate, propionate, or ethanol oxidation.

This publication presents an analysis of the possibilities for home biogas production using an original method. The assumptions for a biogas-generating system and key principles for the methane fermentation process are outlined. Research on the methane fermentation of both kitchen waste and green waste was conducted using a methanogenic consortium. The studies allowed for the characterization of the microorganisms comprising the consortium, and tests confirmed the feasibility of conducting methane fermentation of both types of waste at both laboratory and technical scales, as well as estimating the biogas productivity of the substrates. Based on the research conducted at both scales, the range of conditions under which the biogas production process is possible was determined, with particular reference to temperature conditions and the pH of the leachate. The tests, primarily conducted at a technical scale, allowed for the definition and implementation of optimization measures that resulted in increased process efficiency at the technical scale. Among the main optimization measures were the use of sand as a phase to maintain an anaerobic zone at the start of the process, the use of wood ash to stabilize pH, and the use of substrates and water at room temperature.

The aim of the research was to compare the results of the thermal decomposition of organic matter using different research methods. Experiments were carried out to assess interpretation methods in the characterization of the generation potential of source rocks. The research was conducted for samples of Menilite shales, recognized on the basis of long-term geochemical studies as good quality source rocks. The samples represented the Menilite Beds of the Silesian Unit, taken from the outcrops in the Carpathians. Research using known methods: Rock-Eval pyrolysis (RE), thermogravimetric and calorimetric methods (TG/DSC), and pyrolysis methods combined with gas chromatography analysis (PY-GC), were performed on the same samples- both on rock samples, as well as isolated kerogen. Such integrated studies have so far not been conducted on any rock material. The applied research methods showed a significant comparability of the results obtained. A number of correlations were found between the parameters from individual methods, including: the amount of hydrocarbons separated during PY-GC in the temperature range of 300–650°C, and the parameter S2 from RE, and mass loss in the TG analysis in the same temperature range; S2 values of rock samples and kerogen with weight loss as a result of pyrolysis from TG/DSC analysis at temperatures in the range of 300–650°C; temperature values of the maximum peak S2 (Tpk2) of rock samples with the maximum mass loss temperature during TG analysis; residual carbon content (RC) from RE analysis of rock and kerogen samples with a mass loss as a result of burning residual organic matter from TG/DSC analysis at temperatures in the range of 650–1050°C. The mass loss determined during thermogravimetric analysis, combined with the percentage share of individual hydrocarbon fractions, in which the C9+ fraction is significant, confirms the high petroleum potential of the organic substance contained in the Menilite Beds. Comparative studies of pyrolytic methods: Rock Eval, TG/DSC and PY-GC have proved the compatibility of the results obtained with all methods. Each of the methods also makes it possible to obtain mutually complementary information relating to the TOC, the degree of thermal maturity and type of generated hydrocarbons and other non-hydrocarbon compounds. The conducted tests and performed correlations showed the usefulness of a set of thermal methods to obtain complete information on source rocks.