Stable isotopes of C and H in methane fermentation of agriculture substrates at different temperature conditions

Agricultural substrates (maize silage and cattle manure) were used to carry out methane fermentation process in bioreactors under laboratory conditions. Identical mixtures of these substrates were incubated for 43 days at 20, 30 and 40ºC to determine how di erent temperature conditions a ect the 13C(CH4), H(CH4), and 13C(CO2) values. To ensure correct anaerobic digestion, the following parameters of the organic substrates and fermentation solutions were monitored: total organic carbon (TOC), volatile solids (VS), volatile fatty acids (VFA), chemical oxygen demand (COD) and carbon to nitrogen ratio (C/N). The variants with higher incubation temperature yielded higher amounts of biogas (20ºC=84.5, 30ºC=101.8 and 40ºC=133.3 dm3/kg VS). In the case of gas products of methane fermentation, it was observed that the higher temperature of incubation a ects the depletion in heavy isotopes. At 20ºC, 30ºC, and 40ºC mean values of 13C(CH4) reached −26.4, −29.7, and −35.4h, respectively. Mean values of 2H(CH4) were −311.6, −354.0, and −398.5permil, and of 13C(CO2) +8.9, +3.7, and −2.3h, respectively. Moreover, the apparent fractionation coe cient 13C(CO2-CH4) were calculated, which decreased when the temperature increased. This isotopic tool was used to identify acetoclastic reaction as a dominant methanogenesis pathway. Observed changes in the isotopic composition of gaseous products obtained at different incubation temperatures may indicate decomposition of di erent carbon sources (e.g. lactate, propionate) to acetate and its fermentation by acetoclastic methanogens. It is possible that this was also related to the observation of the various metabolic models due to the varied methanogenic community composition

Lignite biodegradation under conditions of acidic molasses fermentation

Lignite is difficult to degrade, thus stimulation of the autochthonous lignite microflora and introduction of additional microorganisms are required for lignite decomposition. Here, a packed bed reactor, filled with lignite samples from the Konin region (central Poland) was supplied continuously with M9 medium, supplemented with molasses (a by-product from the sugar industry), for 124 days to stimulate the autochthonous lignite microflora. Acidic fermentation of molasses was observed in the bioreactor. The simultaneous decomposition of lignite occurred under this acidic molasses fermentation condition. Our results show decay of free (non-bound) organic compounds during anaerobic lignite biodegradation. The concentrations of n-alkanes, n-alkanols, n-alkanoic acids, diterpenoids, triterpenoids and steroids present in non-biodegraded samples decreased significantly (some compounds to zero) during biodegradation. Interestingly, other compound classes like phenols, ketones and certain organic compounds increased. We interpret this phenomenon as a gradual decomposition of polymers, lignin and cellulose, present in the lignite. These changes resulted from microbial activity since they were not observed in pure solutions of short-chain fatty acids. The 16SrRNA profiling of the microbial community selected in the bioreactor revealed that the dominant bacteria belonged to the Firmicutes, Actinobacteria, Proteobacteria and Bacteroidetes, furthermore representatives of 16 other phyla were also found. All the known taxa of lignocellulolytic bacteria were represented in the microbial community. Synergistic relations between bacteria fermenting molasses and bacteria degrading lignite are assumed. The results confirm lignin degradation in acidic medium by bacteria under anaerobic conditions

Methane-yielding microbial communities processing lactate-rich substrates : a piece of the anaerobic digestion puzzle

Background: 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 experimen‑tal 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.Results: 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, Verrucomicro-bia, 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.Conclusions: 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

Ocena migracji składników gazu ziemnego w złożu Borzęcin na podstawie wyników analiz izotopów trwałych wodoru i węgla

Jedna z pierwszych instalacji EGR (ang. Enhanced Gas Recovery – wzmożonego wydobycia gazu) na świecie funkcjonuje na złożu Borzęcin (SW Polska). Instalacja umożliwia zebranie doświadczenia w rozwoju technologii CCS (ang. Carbon Capture and Storage – wychwyt, transport oraz trwała izolacja CO2) na skalę przemysłową. Ze względu na niewielkie rozmiary złoża technologia ta daje możliwość rozwoju badawczego EGR, przy czym wszystkie procesy związane z zatłaczaniem ditlenku węgla i siarkowodoru są możliwe do obserwacji w stosunkowo niedługiej skali czasu. Głównym celem badań była próba oceny migracji zatłaczanych gazów poprzez pobór i analizę izotopów trwałych wodoru i węgla w gazach z poszczególnych otworów wiertniczych. Dzięki uzyskanym wynikom możliwa jest ocena migracji składników gazu ziemnego w złożu Borzęcin. W rezultacie przeprowadzonych badań otrzymano nowe narzędzie do oceny efektywności wzmożonej eksploatacji gazu, które następnie może być zastosowane w technologiach związanych z CCS. Skład izotopowy wodoru (n = 63) w metanie mieścił się w zakresie od –159,3‰ do –85,2‰ (średnia –114,6‰), a skład izotopowy węgla (n = 92) w tym metanie wyniósł od –46,93‰ do –17,87‰ (średnia –35,22‰). Skład izotopowy węgla (n = 88) w ditlenku węgla osiągnął wartość od –23,33‰ do –3,11‰ (średnia –13,35‰). One of the first installations in the World, based on the EGR (Enhanced Gas Recovery) operates in Borzecin (SW Poland). Thus creating the opportunity to gather experience in the development of CCS (Carbon Capture and Storage) on an industrial scale. Due to the small size of the deposit, the technology allows great research opportunity to develop Enhanced Gas Recovery and all the processes associated with the injection of CO2 and H2S are possible to observe in a relatively short time scale. The main goal of the research is tracing migration fronts of injected gases threw sampling and isotopic analysis of gases from numeral boreholes. Gathered results gave the opportunity to get an appraisal of gas migration in the Borzecin półdeposit. Consequently a new tool for Enhanced Gas Recovery efficiency might be constructed with the potential of being applied in CCS technologies. Isotopic composition of hydrogen (n = 63) in methane varied from –159.3 to –85.2‰ (average –114.6‰) and isotopic composition of carbon including methane (n = 92) varied from –46.93 to –17.87‰ (average –35.22‰). Isotopic composition of carbon in carbon dioxide (n = 88) varied from –23.33 to –3.11‰ (average –13.35‰)

Carbon isotopic calibration of peat-forming plants (Sphagnum sp., Polytrichum sp.) and peat with respect to air-humidity and temperature of vegetation (Śmielec - Jagniątów, Giant Mountains, Poland) =Kalibracja składu izotopowego węgla roślin torfotwórczych (Sphagnum sp., Polytrichum sp.) oraz torfu w nawiązaniu do wilgotności powietrza i temperatury wegetacji (Śmielec - Jagniątów, Karkonosze, Polska)

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Carbon isotopic composition of early-diagenetic methane: variations with sediments depth

We demonstrate the annual cycle of methane in fresh sediments of two lakes – Moszne (E Poland) and Skrzynka (W Poland). The vertical gradient in δ13C(CH4) values varied widely from about -4.5‰/(-1 m) in late summer 1993 to about +2.5‰/(-1 m) in late winter, in the uppermost sediment profiles of about 3-meters in length. These vertical variations apparently are not due to oxidation or temperature changes, but rather to the higher gradient of the downward decrease of production rates via the acetic acid fermen-tation pathway rather than via the CO2-H2 pathway. The production of methane and δ13C(CH4) values are the highest during summer while the lowest during winter, reflect-ed especially during surface sampling. The downward gradient of δ13C in winter, late autumn and, at greater depths, in late summer results from isotope enrichment of the residual pool of precursors of methane, predominantly CO2

Stable isotopes of C and H in methane fermentation of agriculture substrates at different temperature conditions

Agricultural substrates (maize silage and cattle manure) were used to carry out methane fermentation process in bioreactors under laboratory conditions. Identical mixtures of these substrates were incubated for 43 days at 20, 30 and 40ºC to determine how different temperature conditions affect the δ13C(CH4), δH(CH4), and δ13C(CO2) values. To ensure correct anaerobic digestion, the following parameters of the organic substrates and fermentation solutions were monitored: total organic carbon (TOC), volatile solids (VS), volatile fatty acids (VFA), chemical oxygen demand (COD) and carbon to nitrogen ratio (C/N). The variants with higher incubation temperature yielded higher amounts of biogas (20ºC=84.5, 30ºC=101.8 and 40ºC=133.3 dm3/kg VS). In the case of gas products of methane fermentation, it was observed that the higher temperature of incubation affects the depletion in heavy isotopes. At 20ºC, 30ºC, and 40ºC mean values of δ13C(CH4) reached −26.4, −29.7, and −35.4‰, respectively. Mean values of δ2H(CH4) were −311.6, −354.0, and −398.5permil, and of δ13C(CO2) +8.9, +3.7, and −2.3‰, respectively. Moreover, the apparent fractionation coefficient α13C(CO2-CH4) were calculated, which decreased when the temperature increased. This isotopic tool was used to identify acetoclastic reaction as a dominant methanogenesis pathway. Observed changes in the isotopic composition of gaseous products obtained at different incubation temperatures may indicate decomposition of different carbon sources (e.g. lactate, propionate) to acetate and its fermentation by acetoclastic methanogens. It is possible that this was also related to the observation of the various metabolic models due to the varied methanogenic community composition

Variability of sulfur speciation in sediments from Sulejów,Turawa and Siemianówka dam reservoirs (Poland)

A study on sulfur circulation in sediments wascarried out in dam reservoirs (Sulejów, Siemianówka, Turawa)with different hydrological and age characteristicsas well as with a different level of sediment accumulationand organic matter content.Differences in the isotopic composition of SO2−4 in the watercolumn and small variations in the concentration ofthis ion were observed in the Turawa reservoir. The investigationsdid not show vertical variation in the watercolumnconcentrations and isotopic composition. This isdue to the small depths of the reservoir and mixing of water.A part of sulfate sulfur from the water column is reducedby incorporating it into cell structures, while a partof it is deposited in the sediment. The study revealed asmall exchange of SO2−4 between thewater column and thesediment. Depending on the season of the year and thesediment sampling site, biogeochemical transformationsof sulfur species are observed.A significant variation in the biogeochemical processeswas found between the Siemianówka and Sulejów reservoirs,both in the concentrations and in the isotopic compositionof particular sulfur species. This primarily resultsfrom the different characteristics of either of these reservoirs(flows, sedimentation, and material discharge to thelake). The main source of sulfur supplied to the sedimentsin the Siemianówka reservoir is organic sulfur contained inorganic matter deposited at the bottom. In the sediment,organic sulfur is bacterially oxidized and fixed as SO2−4 .This is manifested in a substantial enrichment of sulfate in34S. The presence of polysulfides was found in both reservoirs,but a distinct depletion of δ34S(S2−) in the light sulfurisotope was observed in the Siemianówka reservoir. Ina part of the Sulejów reservoir, polysulfides are oxidized toSO2−4 ,probably at the sediment/water interface

Preliminary results of sulphur isotope studies on sulfides from selected ore deposits and occurrences in the Karkonosze–Izera Massif (the Sudety Mts., Poland)

Preliminary sulphur isotope data are presented for selected ore deposits and occurrences in the Karkonosze-Izera Massif, namely, polymetallic mineralization sites at Budniki, Ciechanowice, Izerskie Garby and Sowia Dolina, and the pyrite deposit at Wieściszowice. The data reveal two populations of δ34S values: from 2.74 to 3.95‰ (pyrrhotites and pyrites in Sowia Dolina, and some pyrites in Wieściszowice) and from 0.79 to 1.8‰ (pyrites in Budniki, Ciechanowice and Izerskie Garby, and some pyrites from Wieściszowice). All of the data are indicative of endogenic sulphur typical of hydrothermal mineralization despite the genetic differences between the sites