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‰)

Differentiation of the Generation Potential of the Menilite and Istebna Beds of the Silesian Unit in the Carpathians Based on Compiled Pyrolytic Studies

The study of the source rocks was carried out with the use of various analytical methods in order to assess their generation potential and to predict the decomposition products of organic matter. The selected samples from the Menilite Beds from the Silesian and Dukla units, as well as the Istebna layers from the Silesian unit, which are classified as weak and medium source rocks in the Carpathian oil system, were examined. The generation potential and type of the products obtained from the pyrolysis of the analyzed source rocks, despite the often comparable overall content of organic matter, are significantly different. Menilite shale generated a higher abundance of hydrocarbons (alkanes, alkenes, and isoalkanes) by stage pyrolysis, which suggested that the organic matter of Menilite shale is different from the Istebna source rocks. Moreover, the thermogravimetric analysis showed a two-stage weight loss in the case of Menilite shales, while the Istebna shales were characterized by a one-stage weight loss at higher temperature. For the Istebna layers, n-alkanes from the C1–C5 range were detected as the main pyrolysis products, which proves the gas-forming type of the organic matter dispersed in these sediments. Rock-Eval analyses showed that the organic matter reached a degree of maturity corresponding to the early thermocatalytic processes (the initial oil window stage) and therefore was able to generate liquid and gaseous hydrocarbons. The comparison of the decomposition temperatures of the organic matter from the Rock-Eval and TG analyses allowed us to conclude that both measurements correlate well and can be equally used to assess the level of thermal transformations of organic matter

Geochemical characterization of samples from Istebna Beds as potentially source rock

W obrębie polskiej części Karpat zewnętrznych – w jednostce śląskiej występują warstwy istebniańskie, które mogą stanowić źródło generacji węglowodorów wypełniających pułapki złożowe. Przeprowadzono geochemiczną analizę substancji organicznej rozproszonej w utworach istebniańskich. Badaniom poddano 23 próbki pochodzące z trzech otworów: Draganowa-1, Osobnica-136, Osobnica-138. Badania prowadzone były na próbkach skalnych oraz wyseparowanym kerogenie. Próbki poddane zostały analizie pirolitycznej Rock-Eval, analizie elementarnej kerogenu oraz jego pirolizie sprzężonej z chromatografią gazową (PY-GC), a także badaniom biomarkerów. Na podstawie badań Rock-Eval oraz analizy elementarnej kerogenu stwierdzono, że substancja organiczna występująca w warstwach istebniańskich zawiera kerogen III typu. Dojrzałość termiczna materii organicznej osiągnęła zakres okna ropnego przy wartościach Tmax z zakresu 425–438°C. Zawartość węgla organicznego rozproszonego w badanych skałach waha się w przedziale od 0,20% do 6,62%. Na podstawie wykonanych badań wytypowano poziom charakteryzujący się najlepszymi parametrami w kontekście macierzystości. Są nim dolne warstwy istebniańskie górnej kredy z otworu Draganowa-1, dla których średnia zawartość węgla organicznego TOC wynosi 2,72%. Badania PY-GC wskazały na mieszany charakter generacyjny kerogenu, który może produkować lekkie, jak i ciężkie węglowodory. Badania biomarkerów potwierdzają zmienny charakter substancji organicznej z przewagą materiału lądowego oraz z obecnością substancji morskiej. Wskaźnik CPI wskazuje na niską jej dojrzałość. Duża zmienność w składzie bituminów może dowodzić istnienia procesów migracyjnych, które zachodziły w obrębie warstw istebniańskich. Różnice te w próbce pobranej z facji piaszczystej mogą świadczyć o jej zbiornikowym charakterze, co w połączeniu z bliskim sąsiedztwem skały macierzystej korzystnie wpływa na przetrwanie wygenerowanych węglowodorów.Within the Silesian unit there are Istebna Beds which can be an additional source of the hydrocarbons filling the reservoir traps. The present work is focused on the geochemical analysis of organic matter dispersed in the Istebna deposits. 23 samples from three wells: Draganowa-1, Osobnica-136 and Osobnica-138 were analyzed. The research was carried out on rock samples and isolated kerogen. Rock-Eval pyrolytic analysis, elemental analysis, pyrolysis coupled with gas chromatography (PY-GC) and biomarker analysis were used to provide data. Based on the Rock-Eval analysis and the elemental analysis, it was found that the organic matter present in the Istebna Beds contains type III kerogen. Thermal maturity of organic matter achieved the oil window and Tmax values range from 425°C to 438°C. The organic carbon content dispersed in the studied rocks varies between 0.20 and 6.62%. Based on the performed research the horizon with the best maturity parameters were selected. These are the Lower Istebna Beds of the Upper Cretaceous from the Draganowa-1 well, for which the average content of total organic carbon is 2.72%. The PY-GC analysis pointed to the mixed character of the kerogen, which can produce light as well as heavy hydrocarbons. Studies of biomarkers confirm the variable nature of organic matter with the predominance of terrestrial material and the presence of marine matter. The CPI indicator indicates low maturity of organic matter. The high variability in the composition of bitumens may indicate the existence of migration processes that occurred within the Istebna Beds. These differences in the sample of the sandy facies may indicate its reservoir character, which in combination with the close vicinity of the source rock favorably affects the preservation of the generated hydrocarbons

Evaluation of sweet spots in Polish shale formations in relation to the selected geochemical parameters

The article focuses on the geochemical parameters of key importance to the assessment of the hydrocarbon potential of shale formations (the content of organic matter and its thermal maturity and degree of transformation). A comparative analysis of the measurements of gas obtained in the process of core desorption with the analysis of saturations obtained from Rock-Eval pyrolysis was performed. Percentage of retained free hydrocarbons in source levels at the calculated generation was determined. Large discrepancies were observed between the measured reflectance values of vitrinite-like macerals or on zooclasts and the calculated VR values from the Tmax parameter. This means limited applicability and universality of Jarvie formula (Wüst, 2013). A new conversion formula was calculated based on a large sample population. Additionally, the article presents the results of isotopic composition analyzes. Large differences in the δ13C methane, ethane and propane values were stated between the wells. The content of higher hydrocarbons in the gas composition is very high, which may indicate thermogenic origin. Most samples are oil-related gas and mixed gas, one sample is condensate related gas (Peters chart). The gas generation from both wells corresponds to the range of the oil window to the beginning of the gas window (VR from about 0.6 to about 1.35%) (Peters et al., 2005). In addition, using data from degasification experiments (total gas quantities) and pyrolysis parameters obtained from Rock Eval analyzes (Tmax and TOC), it was found that the correlation between the maturity of the source organic matter (determined on the basis of Tmax) and the amounts of gas is small (r = 0.37 for total gas). In contrast, the correlation between the organic carbon content (TOC) and the amounts of gas is high for total gas (r = 0.70)

Parameters and methods for evaluation of lignite processing method into biogas

In the article parameters of lignite organic matter conversion into biogas are collated and verified in terms of the process evaluation and control. Possibilities and limitations of usage of the parameters for this type of the process are also indicated. The following parameters were selected: a gas amount and its quality, isotope analysis of the gas produced, measurement of dissolved organic carbon (DOC) in biomass-free liquid media, presence of the VFA (volatile fatty acids) and other possible intermediates of the process in liquid medium, pH, as well as (not discussed in this article) microbiological analyses. On the basis of experiments of Polish lignite biogasification, examples of application of these parameters in laboratory scale for identification of the biodegradation lignite reactions occurrence are presented and discussed. We found that apart from analyses of the biogas produced, the following parameters are also possible to be implemented: DOC, specific surface area of solids measured before and after the process, and the parameters that are normally used for evaluation of rocks’ maturity and origin, i.e. S1, S2 and HI determined from Rock-Eval analysis, as well as GC-MS analysis of EOM (Extractable Organic Matter) separated from lignite. For the analyses of the EOM’s, relatively high amount of solid is required for measurements, limiting its implementation for continuous operations in practice. It was indicated that measurement of elementary coals’ composition, total organic carbon (TOC) in solids or of pH of the liquid are not applicable parameters for verification of the progress of the lignite biogasification process

Comparison of sulfur determination methods based on drilling cores, coal and petroleum samples

The purpose of the work was to select and validate the optimal method for analyzing sulfur content in drilling cores, including those from coal seams. In addition, research was done for petroleum. As part of the work, the results of sulfur content testing were compared by means of elemental analysis in 2 analyzers: in the EA 1108 elemental analyzer, which gives the possibility of burning samples at temperatures up to 1080°C, which is not always sufficient for geological samples, and in the Leco CR12 analyzer expanded with a module for determination of sulfur, which gives the opportunity to perform the analysis at 1350°C. In the course of elemental analysis, free and bound sulfur is transformed into sulfur dioxide SO2, the content of which is measured by means of various detectors: the thermal conductivity detector (TCD) in the EA 1108 analyzer, or the infrared detector in the Leco CR 12 analyzer. Before the comparative tests, the method of sulfur analysis in the Leco CR 12 analyzer was validated. Comparative studies were carried out for rock samples, for coals, for petroleum and for kerogen. As part of the work, elemental analyses of sulfur content were carried out for 23 coal samples, 22 rock samples, 5 kerogen samples separated from these rocks and for 9 petroleum samples. Tested coal and rock material samples came from drill cores from exploratory wells. The methods used for kerogen and for coals with sulfur content over 0.75 wt % have been shown to be compatible. For oils, compatibility was observed above 0.3% sulfur content. Much worse compliance was obtained for rock matter from drilling cores, characterized by dispersion of organic matter. For samples with low sulfur content, determinations in the EA 1108 analyzer provide more reliable results. For media with a high dispersion of organic matter, such as Istebna Beds, the results of determinations in the Leco CR12 analyzer are more reliable due to the size of the analytical sample

A petrological, mineralogical and geochemical study of the Main Dolomite in the Mo-1 borehole

Rocks from the Mo-1 well from the Barnówko-Mostno-Buszewo (BMB) oil and gas field have been studied aiming at constructive results for application in exploration for oil and gas. The study focuses on carbonate deposits from the Main Dolomite horizon, commonly diagenetically altered, where the pore space has been filled by dolomite and anhydrite. Standard petrological analysis was conducted, wide fluid inclusion analyses performed and geochemical character of bitumen determined. Based on microscopic fluorescence studies, three types of fluid inclusions have been distinguished in the vertical column of the well: one-phase non-fluorescent (methane), two-phase non-fluorescent (brine), and two-phase fluorescent inclusions (oil). These three types, further studied microthermometrically, display characteristics of fluid fillings present in the basin and closed as the inclusions in minerals

Assessment of thermal desorption method application for determination of the saturation characteristics along borehole

Celem niniejszej pracy jest przedstawienie szybkiej metody oceny typu wolnych węglowodorów, występujących w profilu otworu, wykorzystującej jako narzędzie pirolizę połączoną z chromatografią gazową (Py-GC). Metoda ta, jako alternatywa dla dotychczas stosowanych – pirolizy Rock-Eval i ekstrakcji rozpuszczalnikowej, mogłaby służyć do typowania poziomów do bardziej szczegółowych badań. W tym celu wykonano badania porównawcze rdzeni pochodzących ze strefy akumulacji ropy naftowej w utworach dolomitu głównego na Niżu Polskim. Wyniki eksperymentów Py-GC prowadzonych w 350°C z detekcją desorbowanych związków na detektorze płomieniowo-jonizacyjnym (Py-GC/FID) dowiodły pozytywnej korelacji z ilością wolnych węglowodorów (S1) uwalnianych w 300°C podczas pirolizy Rock-Eval oraz zawartością ekstrahowalnej substancji organicznej (ESO). Metoda Py-GC/FID ma jednak tę przewagę nad pozostałymi dwiema metodami, że otrzymany chromatogram pokazuje dystrybucję desorbowanych węglowodorów i umożliwia obliczenie niektórych wskaźników geochemicznych, co pozwala na wstępną charakterystykę akumulacji. Ocenę przydatności metody w aspekcie charakterystyki uwalnianych produktów przeprowadzono, wykonując dla kilku badanych rdzeni analizy chromatograficzne GC-FID frakcji nasyconej ekstraktu bitumicznego i obliczając na ich podstawie wskaźniki geochemiczne. Wyniki porównania wykazały generalnie podobieństwo dystrybucji węglowodorów, a dla niektórych próbek również zgodność obliczonych wskaźników. Na tej podstawie należy uznać, że dystrybucja produktów desorpcji Py-GC/FID skał w 350°C pozwala na uzyskanie części informacji dostarczanych przez analizę chromatograficzną GC-FID frakcji nasyconej ekstraktu bitumicznego bez konieczności wstępnej preparatyki chemicznej materiału rdzeniowego, co znacznie skraca czas i obniża koszty analizy. Dystrybucja desorbowanych węglowodorów w korelacji z wynikami pirolizy Rock-Eval może stanowić narzędzie typowania poziomów do szczegółowej charakterystyki geochemicznej. Procedura poszerza zakres badań geochemicznych o kolejną metodę wnoszącą wkład do rozpoznania basenów naftowych.The purpose of this work was to present a quick method for assessing the type of free hydrocarbons occurring in the borehole profile, using pyrolysis combined with gas chromatography (Py-GC) as a tool. This method, as an alternative for the previously used – Rock Eval pyrolysis and solvent extraction – could be used to select levels for more detailed research. For this purpose, comparative tests were carried out of cores originating from the oil accumulation zone in the Main Dolomite formations in the Polish Lowlands. The results of Py-GC experiments carried out at 350ºC with the detection of desorbed compounds on the flame ionization detector (Py-GC/FID) showed a positive correlation with the amount of free hydrocarbons (S1) released at 300ºC during Rock-Eval pyrolysis and the content of extractable organic substance (ESO). However, the Py-GC/FID method has the advantage over the other two methods in that the resulting chromatogram shows the distribution of desorbed hydrocarbons and makes it possible to calculate some geochemical indicators, allowing the preliminary characterization of accumulation. The assessment of the method’s usefulness in terms of the characteristics of released products was carried out by performing GC-FID chromatographic analyses of the saturated fraction of bituminous extract for several tested cores and calculating the geochemical indices on their basis. The results of the comparison generally demonstrated a similarity of hydrocarbon distribution, and for some samples also compliance with the calculated indices. On this basis, it should be considered that the distribution of Py-GC/FID desorption products of rocks at 350ºC allows obtaining part of the information provided by GC-FID chromatographic analysis of the saturated fraction of the bituminous extract without the need for chemical pre-treatment of the core material, which significantly reduces the time and costs of analysis. The distribution of desorbed hydrocarbons in correlation with the results of Rock Eval pyrolysis can be a tool for selecting levels for detailed geochemical recognition. The procedure extends the scope of geochemical research with another method contributing to the recognition of oil basins