scholarly journals Indicative Marker Microbiome Structures Deduced from the Taxonomic Inventory of 67 Full-Scale Anaerobic Digesters of 49 Agricultural Biogas Plants

2021 ◽  
Vol 9 (7) ◽  
pp. 1457
Author(s):  
Julia Hassa ◽  
Johanna Klang ◽  
Dirk Benndorf ◽  
Marcel Pohl ◽  
Benedikt Hülsemann ◽  
...  
Keyword(s):  
Stable Process ◽  
Process Condition ◽  
Full Scale ◽  
Process Models ◽  
Process Efficiency ◽  
Process Conditions ◽  
Rrna Gene ◽  
General Process ◽  
Specific Distribution ◽  
Biogas Plants

There are almost 9500 biogas plants in Germany, which are predominantly operated with energy crops and residues from livestock husbandry over the last two decades. In the future, biogas plants must be enabled to use a much broader range of input materials in a flexible and demand-oriented manner. Hence, the microbial communities will be exposed to frequently varying process conditions, while an overall stable process must be ensured. To accompany this transition, there is the need to better understand how biogas microbiomes respond to management measures and how these responses affect the process efficiency. Therefore, 67 microbiomes originating from 49 agricultural, full-scale biogas plants were taxonomically investigated by 16S rRNA gene amplicon sequencing. These microbiomes were separated into three distinct clusters and one group of outliers, which are characterized by a specific distribution of 253 indicative taxa and their relative abundances. These indicative taxa seem to be adapted to specific process conditions which result from a different biogas plant operation. Based on these results, it seems to be possible to deduce/assess the general process condition of a biogas digester based solely on the microbiome structure, in particular on the distribution of specific indicative taxa, and without knowing the corresponding operational and chemical process parameters. Perspectively, this could allow the development of detection systems and advanced process models considering the microbial diversity.

scholarly journals Monitoring N : P Ratio and Cd, Cu, Pb, and Zn Contents in Different Types of Anaerobic Digestates: A Six-Year Study Case

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Christina-Luise Roß ◽  
Kerstin Nielsen ◽  
Jorita Krieger ◽  
Marieke Hoffmann ◽  
Karen Sensel-Gunke ◽  
...  
Keyword(s):  
Stable Process ◽  
Zinc Content ◽  
Pig Manure ◽  
Process Conditions ◽  
Pig Slurry ◽  
Large Variability ◽  
Lead And Zinc ◽  
German Legislation ◽  
Biogas Plants

Depending on the quality of the input substrates, process parameters, and postfermentation treatments, digestates may contain a broad spectrum of potentially toxic elements. We suspected that these contents may vary on a broad scale even under seemingly stable process conditions at the biogas plant. Digestates from four biogas plants were therefore continuously analyzed for their contents of phosphorus, nitrogen, cadmium, copper, lead, and zinc over a period of six years. The input substrates varied between the plants (e.g., cattle and pig slurry and rye and maize silage), but were the same for each plant over the whole period. The N : P ratio of the digestates ranged from 2 to 24, with the digestate coming from cofermentation of pig slurry and energy crops (“DG Pig”) having the widest range of N : P ratio over the years. Heavy metal loads of all digestates and during all evaluations did not exceed the limits set by European or German legislation, but as previously expected, showed a large variability especially if cattle or pig manure were used as substrates. Copper content of Cattle slurry before digestion was 897.7 mg kg−1 DM in one case, and zinc content of DG Pig reached 590.2 mg kg−1 DM also once during the investigation. As a result, we strongly recommend to monitor especially phosphorus, copper, and zinc contents in digestates very closely and in short intervals.

Full scale experience of two stage thermophilic/mesophilic sludge digestion

1997 ◽  
Vol 36 (6-7) ◽  
pp. 449-456 ◽  
Author(s):  
Jürgen Oles ◽  
Norbert Dichtl ◽  
Hans-hermann Niehoff
Keyword(s):  
Degradation Process ◽  
Pilot Scale ◽  
Full Scale ◽  
Process Efficiency ◽  
Anaerobic Sludge ◽  
Process Conditions ◽  
Two Stage ◽  
Operational Conditions ◽  
Digestion Process ◽  
General Goals

The general goals of anaerobic sludge stabilisation are degradation of organic substances, reduction of solids, decrease of pathogenic bacterias, improvement of dewatering capabilities and production of biogas. The anaerobic degradation process can be divided in several steps with different optimum operational conditions. This gives the possibility to design treatment plants as a two-stage process, optimizing the process conditions in each step and thereby leading to an overall increase in process efficiency. Research results in lab scale and pilot scale have shown that a two-stage digestion process with a high loaded first thermophilic (50-55°C) stage and a second stage under mesophilic (35-37°C) conditions with sufficient retention time will lead to the best results. After giving a short summary of the development of the two-stage thermophilic/mesophilic digestion process the paper will present full scale experiences with this system in Germany.

scholarly journals Microbiome Diversity and Community-Level Change Points within Manure-Based Small Biogas Plants

2020 ◽  
Vol 8 (8) ◽  
pp. 1169
Author(s):  
Susanne Theuerl ◽  
Johanna Klang ◽  
Benedikt Hülsemann ◽  
Torsten Mächtig ◽  
Julia Hassa
Keyword(s):  
Amplicon Sequencing ◽  
Community Level ◽  
Chicken Manure ◽  
Change Points ◽  
Process Conditions ◽  
Rrna Gene ◽  
Level Change ◽  
Microbiome Diversity ◽  
Biogas Plants ◽  
Critical Process

Efforts to integrate biogas plants into bioeconomy concepts will lead to an expansion of manure-based (small) biogas plants, while their operation is challenging due to critical characteristics of some types of livestock manure. For a better process understanding, in this study, three manure-based small biogas plants were investigated with emphasis on microbiome diversity. Due to varying digester types, feedstocks, and process conditions, 16S rRNA gene amplicon sequencing showed differences in the taxonomic composition. Dynamic variations of each investigated biogas plant microbiome over time were analyzed by terminal restriction fragment length polymorphism (TRFLP), whereby nonmetric multidimensional scaling (NMDS) revealed two well-running systems, one of them with a high share of chicken manure, and one unstable system. By using Threshold Indicator Taxa Analysis (TITAN), community-level change points at ammonium and ammonia concentrations of 2.25 g L-1 and 193 mg L-1 or volatile fatty acid concentrations of 0.75 g L-1were reliably identified which are lower than the commonly reported thresholds for critical process stages based on chemical parameters. Although a change in the microbiome structure does not necessarily indicate an upcoming critical process stage, the recorded community-level change points might be a first indication to carefully observe the process.

scholarly journals Correlations between the Composition of Liquid Fraction of Full-Scale Digestates and Process Conditions

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 971
Author(s):  
Afifi Akhiar ◽  
Felipe Guilayn ◽  
Michel Torrijos ◽  
Audrey Battimelli ◽  
Abd Halim Shamsuddin ◽  
...  
Keyword(s):  
High Efficiency ◽  
Liquid Fraction ◽  
Separation Process ◽  
Full Scale ◽  
Process Equipment ◽  
Process Conditions ◽  
Liquid Separation ◽  
Biogas Plants ◽  
Solid Liquid ◽  
Solid Liquid Separation

Fast development of centralized agricultural biogas plants leads to high amounts of digestate production. The treatment and disposal of liquid fractions after on-site digestate solid–liquid separation remains problematic due to their high organic, nutrient and aromatic contents. This work aims to study the variability of the remaining compounds in the digestate liquid fractions in relation to substrate origin, process parameters and solid–liquid separation techniques. Twenty-nine digestates from full-scale codigestion biogas plants and one waste activated sludge (WAS) digestate were collected and characterized. This study highlighted the combined effect of the solid–liquid separation process and the anaerobic digestion feedstock on the characteristics of liquid fractions of digestates. Two major clusters were found: (1) liquid fractions from high efficiency separation process equipment (e.g., centrifuge and others with addition of coagulant, flocculent or polymer) and (2) liquid fractions from low efficiency separation processes (e.g., screw press, vibrating screen and rotary drum), in this latter case, the concentration of chemical oxygen demand (COD) was associated with the proportion of cow manure and energy crops at biogas plant input. Finally, SUVA254, an indicator for aromatic molecule content and the stabilization of organic matter, was associated with the hydraulic retention time (HRT).

scholarly journals Comparison of Biological Efficiency Assessment Methods and Their Application to Full-Scale Biogas Plants

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2381
Author(s):  
Benedikt Hülsemann ◽  
Torsten Mächtig ◽  
Marcel Pohl ◽  
Jan Liebetrau ◽  
Joachim Müller ◽  
...  
Keyword(s):  
Full Scale ◽  
Assessment Methods ◽  
Biological Efficiency ◽  
Process Conditions ◽  
Site Specific ◽  
Efficiency Assessment ◽  
Biogas Plants ◽  
Methane Potential ◽  
Energy Balances

For calculation of biological efficiency of a biogas plant (BP), it is required to determine the specific methane potential (SMP) of the substrate. A study comparing available methods for determination of SMP and the comparison with data of full-scale BPs is missing but necessary according to the differences in process conditions between both. Firstly, mass and mass associated energy balances of 33 full-scale BPs were calculated and evaluated. The results show plausible data for only 55% of the investigated BPs. Furthermore, conversion and yield efficiencies were calculated according to six different methods for SMP determination. The results show a correlation between the measured on-site specific methane yield and the calculated SMP by methods based on biological degradability. However, these methods underestimate the SMP. Calculated SMPs based on calorific values are higher, but less sensitive. A combination of biochemical and energetical methods is a promising approach to evaluate the efficiency.

Full Scale Investigations on Enhanced Biological Phosphorus Removal – P-Release in the Anaerobic Reactor

1994 ◽  
Vol 29 (7) ◽  
pp. 153-156 ◽  
Author(s):  
D. Wedi ◽  
P. A. Wilderer
Keyword(s):  
Phosphorus Removal ◽  
Full Scale ◽  
Process Conditions ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Anaerobic Reactor ◽  
P Release ◽  
Acinetobacter Sp ◽  
Biological Phosphorus ◽  
P Removal

Most of the fundamental processes responsible for enhanced biological phosphorus removal (EBPR) were obtained through laboratory tests under defined conditions with pure or enriched cultures. Acinetobacter sp. was identified as the most important group of bacteria responsible for bio-P removal. Full scale data showed, however, that laboratory results do not match full scale results well enough. There is a lack of data on the effects of sub-optimal process conditions such as inadequate availability of volatile fatty acids (VFA), high nitrate recycle, storm water inflow or low temperatures. In this paper the results of full scale experiments on P-release are presented and compared with theoretical values. Measurements at a full scale Phoredox-system showed a surprisingly low P-release in the anaerobic reactor. Only 4 to 10% of the phosphorus in the activated sludge was released in the bulk liquid. With laboratory batch-tests, a maximum of 20% of the P in the sludge could be released. It is assumed that under the prevailing process conditions either the fraction of Acinetobacter sp. was very small, or bacteria other than Acinetobacter sp. were responsible for the P-removal, or most of the phosphorus was bound chemically but mediated by biological processes.

Removal of sulphite-reducing clostridia spores by full-scale water treatment processes as a surrogate for protozoan (oo)cysts removal

2000 ◽  
Vol 41 (7) ◽  
pp. 165-171 ◽  
Author(s):  
W. A. Hijnen ◽  
J. Willemsen-Zwaagstra ◽  
P. Hiemstra ◽  
G. J. Medema ◽  
D. van der Kooij
Keyword(s):  
Water Treatment ◽  
Removal Efficiency ◽  
Water Quality Monitoring ◽  
Full Scale ◽  
Process Conditions ◽  
Safe Drinking Water ◽  
Unit Process ◽  
Treatment Processes ◽  
Scale Unit ◽  
Micro Organisms

At eight full-scale water treatment plants in the Netherlands the removal of spores of sulphite-reducing clostridia (SSRC) was determined. By sampling and processing large volumes of water (1 up to 500 litres) SSRC were detected after each stage of the treatment. This enabled the assessment of the removal efficiency of the full-scale unit processes for persistent micro-organisms. A comparison with literature data on the removal of Cryptosporidium and Giardia by the same type of processes revealed that SSRC can be considered as a potential surrogate. The average Decimal Elimination Capacity (DEC) of the overall treatment plants ranged from 1.3–4.3 log. The observed actual log removal of SSRC by the unit processes and the overall treatment at one of the studied locations showed that the level of variation in removal efficiency was approximately 2 log. Moreover, from the actual log removal values it was observed that a low SSRC removal by one unit process is partly compensated by a higher removal by subsequent unit processes at this location. SSRC can be used for identification of the process conditions that cause variation in micro-organism removal which may lead to process optimization. Further research is necessary to determine the optimal use of SSRC in water quality monitoring for the production of microbiologically safe drinking water.

scholarly journals Cure Kinetics Modeling of a High Glass Transition Temperature Epoxy Molding Compound (EMC) Based on Inline Dielectric Analysis

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1734
Author(s):  
Erick Franieck ◽  
Martin Fleischmann ◽  
Ole Hölck ◽  
Larysa Kutuzova ◽  
Andreas Kandelbauer
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Kinetic Parameters ◽  
Measurement Techniques ◽  
Process Conditions ◽  
Dielectric Analysis ◽  
High Glass Transition Temperature ◽  
General Process ◽  
Molding Compound

We report on the cure characterization, based on inline monitoring of the dielectric parameters, of a commercially available epoxy phenol resin molding compound with a high glass transition temperature (>195 °C), which is suitable for the direct packaging of electronic components. The resin was cured under isothermal temperatures close to general process conditions (165–185 °C). The material conversion was determined by measuring the ion viscosity. The change of the ion viscosity as a function of time and temperature was used to characterize the cross-linking behavior, following two separate approaches (model based and isoconversional). The determined kinetic parameters are in good agreement with those reported in the literature for EMCs and lead to accurate cure predictions under process-near conditions. Furthermore, the kinetic models based on dielectric analysis (DEA) were compared with standard offline differential scanning calorimetry (DSC) models, which were based on dynamic measurements. Many of the determined kinetic parameters had similar values for the different approaches. Major deviations were found for the parameters linked to the end of the reaction where vitrification phenomena occur under process-related conditions. The glass transition temperature of the inline molded parts was determined via thermomechanical analysis (TMA) to confirm the vitrification effect. The similarities and differences between the resulting kinetics models of the two different measurement techniques are presented and it is shown how dielectric analysis can be of high relevance for the characterization of the curing reaction under conditions close to series production.

scholarly journals Improvement of Biogas Quality and Quantity for Small-Scale Biogas-Electricity Generation Application in off-Grid Settings: A Field-Based Study

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3088
Author(s):  
Henry Wasajja ◽  
Saqr A. A. Al-Muraisy ◽  
Antonella L. Piaggio ◽  
Pamela Ceron-Chafla ◽  
Purushothaman Vellayani Aravind ◽  
...  
Keyword(s):  
Electricity Generation ◽  
Relevant Literature ◽  
Electrical Power ◽  
Process Efficiency ◽  
Electricity Production ◽  
Small Scale ◽  
Buffer System ◽  
Biogas Plants ◽  
Operational Practices ◽  
Pre Treatment

Small-scale electrical power generation (<100 kW) from biogas plants to provide off-grid electricity is of growing interest. Currently, gas engines are used to meet this demand. Alternatively, more efficient small-scale solid oxide fuel cells (SOFCs) can be used to enhance electricity generation from small-scale biogas plants. Most electricity generators require a constant gas supply and high gas quality in terms of absence of impurities like H2S. Therefore, to efficiently use the biogas from existing decentralized anaerobic digesters for electricity production, higher quality and stable biogas flow must be guaranteed. The installation of a biogas upgrading and buffer system could be considered; however, the cost implication could be high at a small scale as compared to locally available alternatives such as co-digestion and improved digester operation. Therefore, this study initially describes relevant literature related to feedstock pre-treatment, co-digestion and user operational practices of small-scale digesters, which theoretically could lead to major improvements of anaerobic digestion process efficiency. The theoretical preamble is then coupled to the results of a field study, which demonstrated that many locally available resources and user practices constitute frugal innovations with potential to improve biogas quality and digester performance in off-grid settings.

Operational results of an agricultural biogas plant equipped with modern instrumentation and automation

2008 ◽  
Vol 57 (6) ◽  
pp. 803-808 ◽  
Author(s):  
J. Wiese ◽  
O. Kujawski
Keyword(s):  
Energy Crops ◽  
Full Scale ◽  
Biogas Plant ◽  
Biogas Plants ◽  
Technical Details ◽  
Modern Instrumentation

Agricultural biogas plants based on energy crops gain more and more importance because of numerous energetic, environmental and agricultural benefits. In contrast to older biogas plants, the newest generation of biogas plants is equipped with modern ICA equipment and reliable machines/engines. In this paper, the authors present technical details and operational results of a modern full-scale agricultural biogas plant using energy crops.

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