Public acceptance is one of the fundamental prerequisites for geological CO2 storage. In highly p... more Public acceptance is one of the fundamental prerequisites for geological CO2 storage. In highly populated areas like central Europe, especially in the vicinity of metropolitan areas like Berlin, underground operations are in the focus of the people living next to the site, the media, and politics. To gain acceptance, all these groups - the people in the neighbourhood, journalists, and authorities - need to be confident of the security of the planned storage operation as well as the long term security of storage. A very important point is to show that the technical risks of CO2 storage can be managed with the help of a proper short and long term monitoring concept, as well as appropriate mitigation technologies e.g adequate abandonment procedures for leaking wells. To better explain the possible risks examples for leakage scenarios help the public to assess and to accept the technical risks of CO2 storage. At Ketzin we tried the following approach that can be summed up on the basis: ...
Filamentous bacteria such as Microthrix parvicella can cause serious foaming and floating sludge ... more Filamentous bacteria such as Microthrix parvicella can cause serious foaming and floating sludge problems in anaerobic digesters fed with sewage sludge. The sewage sludge and oil co-fermenting laboratory-scale biogas digesters in this study were fed with substrates from a foaming-prone full-scale biogas plant containing the filamentous bacterium M. parvicella. At 37 °C, in both pneumatically mixed digesters a highly viscous and approximately 3 cm thick floating sludge was observed. A gradual increase of the temperature from 37 °C to 56 °C led to a significant decrease in the floating sludge thickness, which correlated with a strong decrease in the abundance of M. parvicella in the digestate. Furthermore, the stepwise temperature increase allowed for an adaption of the microbial community and prevented process failure. The study indicates that already a moderate temperature increase from 37 °C to 41 °C might help to control the M. parvicella abundance in full-scale biogas plants.
Following a process failure in a full-scale biogas reactor, different counter measures were under... more Following a process failure in a full-scale biogas reactor, different counter measures were undertaken to stabilize the process of biogas formation, including the reduction of the organic loading rate, the addition of sodium hydroxide (NaOH), and the introduction of calcium oxide (CaO). Corresponding to the results of the process recovery in the full-scale digester, laboratory experiments showed that CaO was more capable of stabilizing the process than NaOH. While both additives were able to raise the pH to a neutral milieu (pH>7.0), the formation of aggregates was observed particularly when CaO was used as the additive. Scanning electron microscopy investigations revealed calcium phosphate compounds in the core of the aggregates. Phosphate seemed to be released by phosphorus-accumulating organisms, when volatile fatty acids accumulated. The calcium, which was charged by the CaO addition, formed insoluble salts with long chain fatty acids, and caused the precipitation of calcium phosphate compounds. These aggregates were surrounded by a white layer of carbon rich organic matter, probably consisting of volatile fatty acids. Thus, during the process recovery with CaO, the decrease in the amount of accumulated acids in the liquid phase was likely enabled by (1) the formation of insoluble calcium salts with long chain fatty acids, (2) the adsorption of volatile fatty acids by the precipitates, (3) the acid uptake by phosphorus-accumulating organisms and (4) the degradation of volatile fatty acids in the aggregates. Furthermore, this mechanism enabled a stable process performance after re-activation of biogas production. In contrast, during the counter measure with NaOH aggregate formation was only minor resulting in a rapid process failure subsequent the increase of the organic loading rate.
International Journal of Greenhouse Gas Control, 2010
Stable carbon isotopes may serve as useful tracers to monitor the fate and migration of injected ... more Stable carbon isotopes may serve as useful tracers to monitor the fate and migration of injected CO2 gas in the subsurface. This is true as long as the already present dissolved inorganic carbon (DIC) has a different isotopic composition (δ13CDIC) than the injected CO2 (δCCO213). After dissolution and turnover of the injected CO2 to DIC, mixture of both sources (δCCO213
ABSTRACT For the utilization of deep saline aquifers in the frame of geotechnical use, such as ge... more ABSTRACT For the utilization of deep saline aquifers in the frame of geotechnical use, such as geological sequestration of CO2, H2 or energy storage, a baseline characterization of pristine reservoir rock cores is required to monitor changes in the indigenous microbial communities and pore fluids, and to study alterations in rock characteristics resulting from interaction with geological storage technologies. However, drilling procedures and technical fluids, particularly drill mud, are sources of core contamination. To measure the penetration of drill mud into the cores, three tracers (fluorescein, microspheres, and 4′,6-diamidino-2-phenylindole stained bacteria) were tested under laboratory conditions. The flow of drill mud into core samples was induced by applying uniaxial pressure differentials to the core, and the penetration depth was microscopically determined for each tracer. Fluorescein was extracted from the rock samples and quantified fluorometrically. The results indicate that all tested tracers are suitable for tracking drill-mud penetration. The actual penetration depth seems to be related to differences in mineral composition and texture as well as microfractures. Among all tested tracers, fluorescein labelling is the simplest, cheapest and most accurate method for analyzing the contamination of rock cores by technical fluids. The application of this tracer was successfully applied during two deep drilling campaigns at the CO2 storage pilot site in Ketzin, Germany. The results highlight that the use of tracers is indispensable to ensure the quality of core samples for microbiological and biogeochemical analysis.
Public acceptance is one of the fundamental prerequisites for geological CO2 storage. In highly p... more Public acceptance is one of the fundamental prerequisites for geological CO2 storage. In highly populated areas like central Europe, especially in the vicinity of metropolitan areas like Berlin, underground operations are in the focus of the people living next to the site, the media, and politics. To gain acceptance, all these groups - the people in the neighbourhood, journalists, and authorities - need to be confident of the security of the planned storage operation as well as the long term security of storage. A very important point is to show that the technical risks of CO2 storage can be managed with the help of a proper short and long term monitoring concept, as well as appropriate mitigation technologies e.g adequate abandonment procedures for leaking wells. To better explain the possible risks examples for leakage scenarios help the public to assess and to accept the technical risks of CO2 storage. At Ketzin we tried the following approach that can be summed up on the basis: ...
Filamentous bacteria such as Microthrix parvicella can cause serious foaming and floating sludge ... more Filamentous bacteria such as Microthrix parvicella can cause serious foaming and floating sludge problems in anaerobic digesters fed with sewage sludge. The sewage sludge and oil co-fermenting laboratory-scale biogas digesters in this study were fed with substrates from a foaming-prone full-scale biogas plant containing the filamentous bacterium M. parvicella. At 37 °C, in both pneumatically mixed digesters a highly viscous and approximately 3 cm thick floating sludge was observed. A gradual increase of the temperature from 37 °C to 56 °C led to a significant decrease in the floating sludge thickness, which correlated with a strong decrease in the abundance of M. parvicella in the digestate. Furthermore, the stepwise temperature increase allowed for an adaption of the microbial community and prevented process failure. The study indicates that already a moderate temperature increase from 37 °C to 41 °C might help to control the M. parvicella abundance in full-scale biogas plants.
Following a process failure in a full-scale biogas reactor, different counter measures were under... more Following a process failure in a full-scale biogas reactor, different counter measures were undertaken to stabilize the process of biogas formation, including the reduction of the organic loading rate, the addition of sodium hydroxide (NaOH), and the introduction of calcium oxide (CaO). Corresponding to the results of the process recovery in the full-scale digester, laboratory experiments showed that CaO was more capable of stabilizing the process than NaOH. While both additives were able to raise the pH to a neutral milieu (pH>7.0), the formation of aggregates was observed particularly when CaO was used as the additive. Scanning electron microscopy investigations revealed calcium phosphate compounds in the core of the aggregates. Phosphate seemed to be released by phosphorus-accumulating organisms, when volatile fatty acids accumulated. The calcium, which was charged by the CaO addition, formed insoluble salts with long chain fatty acids, and caused the precipitation of calcium phosphate compounds. These aggregates were surrounded by a white layer of carbon rich organic matter, probably consisting of volatile fatty acids. Thus, during the process recovery with CaO, the decrease in the amount of accumulated acids in the liquid phase was likely enabled by (1) the formation of insoluble calcium salts with long chain fatty acids, (2) the adsorption of volatile fatty acids by the precipitates, (3) the acid uptake by phosphorus-accumulating organisms and (4) the degradation of volatile fatty acids in the aggregates. Furthermore, this mechanism enabled a stable process performance after re-activation of biogas production. In contrast, during the counter measure with NaOH aggregate formation was only minor resulting in a rapid process failure subsequent the increase of the organic loading rate.
International Journal of Greenhouse Gas Control, 2010
Stable carbon isotopes may serve as useful tracers to monitor the fate and migration of injected ... more Stable carbon isotopes may serve as useful tracers to monitor the fate and migration of injected CO2 gas in the subsurface. This is true as long as the already present dissolved inorganic carbon (DIC) has a different isotopic composition (δ13CDIC) than the injected CO2 (δCCO213). After dissolution and turnover of the injected CO2 to DIC, mixture of both sources (δCCO213
ABSTRACT For the utilization of deep saline aquifers in the frame of geotechnical use, such as ge... more ABSTRACT For the utilization of deep saline aquifers in the frame of geotechnical use, such as geological sequestration of CO2, H2 or energy storage, a baseline characterization of pristine reservoir rock cores is required to monitor changes in the indigenous microbial communities and pore fluids, and to study alterations in rock characteristics resulting from interaction with geological storage technologies. However, drilling procedures and technical fluids, particularly drill mud, are sources of core contamination. To measure the penetration of drill mud into the cores, three tracers (fluorescein, microspheres, and 4′,6-diamidino-2-phenylindole stained bacteria) were tested under laboratory conditions. The flow of drill mud into core samples was induced by applying uniaxial pressure differentials to the core, and the penetration depth was microscopically determined for each tracer. Fluorescein was extracted from the rock samples and quantified fluorometrically. The results indicate that all tested tracers are suitable for tracking drill-mud penetration. The actual penetration depth seems to be related to differences in mineral composition and texture as well as microfractures. Among all tested tracers, fluorescein labelling is the simplest, cheapest and most accurate method for analyzing the contamination of rock cores by technical fluids. The application of this tracer was successfully applied during two deep drilling campaigns at the CO2 storage pilot site in Ketzin, Germany. The results highlight that the use of tracers is indispensable to ensure the quality of core samples for microbiological and biogeochemical analysis.
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Papers by H. Würdemann