Article

Biogas production: current state and perspectives. Appl Microbiol Biot

Johann Heinrich von Thünen-Institute, Braunschweig, Germany.
Applied Microbiology and Biotechnology (Impact Factor: 3.34). 09/2009; 85(4):849-60. DOI: 10.1007/s00253-009-2246-7
Source: PubMed

ABSTRACT

Anaerobic digestion of energy crops, residues, and wastes is of increasing interest in order to reduce the greenhouse gas emissions and to facilitate a sustainable development of energy supply. Production of biogas provides a versatile carrier of renewable energy, as methane can be used for replacement of fossil fuels in both heat and power generation and as a vehicle fuel. For biogas production, various process types are applied which can be classified in wet and dry fermentation systems. Most often applied are wet digester systems using vertical stirred tank digester with different stirrer types dependent on the origin of the feedstock. Biogas is mainly utilized in engine-based combined heat and power plants, whereas microgas turbines and fuel cells are expensive alternatives which need further development work for reducing the costs and increasing their reliability. Gas upgrading and utilization as renewable vehicle fuel or injection into the natural gas grid is of increasing interest because the gas can be used in a more efficient way. The digestate from anaerobic fermentation is a valuable fertilizer due to the increased availability of nitrogen and the better short-term fertilization effect. Anaerobic treatment minimizes the survival of pathogens which is important for using the digested residue as fertilizer. This paper reviews the current state and perspectives of biogas production, including the biochemical parameters and feedstocks which influence the efficiency and reliability of the microbial conversion and gas yield.

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Available from: Peter Weiland, Dec 13, 2013
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    • "Consequently, microbial communities are very complex systems and mathematical modeling has been shown to be a valuable tool to gain better understanding about the relevant interactions and community behavior[6]. In biogas plants, for example , process failures (e.g., acidification) may occur if the microorganisms involved are not in a stable steady state[7]. Here, modeling might help to identify reasons for process failures and to predict optimal conditions for a stable process. "
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    ABSTRACT: Microbial communities are ubiquitous in nature and play a major role in ecology, medicine, and various industrial processes. In this study, we used stoichiometric metabolic modeling to investigate a community of three species, Desulfovibrio vulgaris, Methanococcus maripaludis, and Methanosarcina barkeri, which are involved in acetogenesis and methanogenesis in anaerobic digestion for biogas production. We first constructed and validated stoichiometric models of the core metabolism of the three species which were then assembled to community models. The community was simulated by applying the previously described concept of balanced growth demanding that all organisms of the community grow with equal specific growth rate. For predicting community compositions, we propose a novel hierarchical optimization approach: first, similar to other studies, a maximization of the specific community growth rate is performed which, however, often leads to a wide range of optimal community compositions. In a secondary optimization, we therefore also demand that all organisms must grow with maximum biomass yield (optimal substrate usage) reducing the range of predicted optimal community compositions. Simulating two-species as well as three-species communities of the three representative organisms, we gained several important insights. First, using our new optimization approach we obtained predictions on optimal community compositions for different substrates which agree well with measured data. Second, we found that the ATP maintenance coefficient influences significantly the predicted community composition, especially for small growth rates. Third, we observed that maximum methane production rates are reached under high-specific community growth rates and if at least one of the organisms converts its substrate(s) with suboptimal biomass yield. On the other hand, the maximum methane yield is obtained at low community growth rates and, again, when one of the organisms converts its substrates suboptimally and thus wastes energy. Finally, simulations in the three-species community clarify exchangeability and essentiality of the methanogens in case of alternative substrate usage and competition scenarios. In summary, our study presents new methods for stoichiometric modeling of microbial communities in general and provides valuable insights in interdependencies of bacterial species involved in the biogas process.
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    • "In the agricultural context, energy crops represent one of the most important sources for biogas production in Europe (Weiland, 2010). In Germany, for example , more than 50% of total biogas production derives from energy crops, of which corn (Zea mays L.) is the most used (Weiland, 2010). This has led to a conflict for soil use, i.e. energy vs. food production (Britz and Delzeit, 2013). "
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    ABSTRACT: Anaerobic digestion produces a biologically stable and high-value fertilizer product, the digestate, which can be used as an alternative to mineral fertilizers on crops. However, misuse of digestate can lead to annoyance for the public (odours) and to environmental problems such as nitrate leaching and ammonia emissions into the air. Full field experimental data are needed to support the use of digestate in agriculture, promoting its correct management. In this work, short-term experiments were performed to substitute mineral N fertilizers (urea) with digestate and products derived from it to the crop silage maize. Digestate and the liquid fraction of digestate were applied to soil at pre-sowing and as topdressing fertilizers in comparison with urea, both by surface application and subsurface injection during the cropping seasons 2012 and 2013. After each fertilizer application, both odours and ammonia emissions were measured, giving data about digestate and derived products' impacts.The AD products could substitute for urea without reducing crop yields, apart from the surface application of AD-derived fertilizers. Digestate and derived products, because of high biological stability acquired during the AD, had greatly reduced olfactometry impact, above all when they were injected into soils (82-88% less odours than the untreated biomass, i.e. cattle slurry). Ammonia emission data indicated, as expected, that the correct use of digestate and derived products required their injection into the soil avoiding, ammonia volatilization into the air and preserving fertilizer value. Sub-surface injection allowed ammonia emissions to be reduced by 69% and 77% compared with surface application during the 2012 and 2013 campaigns.
    No preview · Article · Mar 2016 · Science of The Total Environment
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    • "Due to the increasing global energy demand, renewable energy sources such as solar, wind and biomass have become more important. In this regard, especially the utilization of animal manure, energy crops and industrial food waste for the production of biogas, is an attractive alternative to fossil fuels [1] [2]. A multitude of microorganisms is responsible for the conversion of organic material to methane and carbon dioxide under anaerobic conditions [3]. "
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    ABSTRACT: An enzyme-based multi-parameter sensor chip for the simultaneous measurement of formate, D- and L-lactate is presented. Thereby, the combination of a diaphorase (DIA) from Clostridium kluyveri with different NAD+-dependent dehydrogenases enables the specific recognition of each compound. The amperometric detection is performed via monitoring of the oxidation current of enzymatically produced hexacyanoferrate(II) at +300 mV vs. Ag/AgCl. Chemical cross-linking with glutaraldehyde is used for enzyme immobilization. Thereby, the sensor signal is investigated at different concentrations of the cross-linker in the enzyme membrane. The obtained results indicate that by optimization of the immobilization matrix, the sensor performance can be improved.
    Full-text · Article · Dec 2015 · Procedia Engineering
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