Increase of methane formation by ethanol addition during continuous fermentation of biogas sludge

Refai, Sarah; Wassmann, Kati; Helmont, Sebastian van; Berger, Stefanie; Deppenmeier, Uwe

doi:10.1007/s10295-014-1524-2

Cited by 6 publications

(4 citation statements)

References 23 publications

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“…CH 4 production was significantly lower at all individual time points in reactors with increased ammonia concentration (average production during experiment 0.9 ± 0.3 μmol/g·h) compared to control fermenters (Wilcoxon rank sum test; W = 16, p < 0.03). Reactor performance of the control group (average production during experiment 1.9 ± 0.1 μmol/g·h) was comparable to previous studies under similar conditions (Refai et al, 2014b).…”

Section: Resultssupporting

confidence: 84%

“…Eight small-scale fed batch reactors used in the experiment were set up as previously described by Refai et al (2014a,b). Briefly, 200 g of biogas reactor material was transferred under anaerobic conditions to 1-L gas-tight glass bottles sealed with butyl rubber stoppers and locked with aluminum screw caps.…”

Section: Methodsmentioning

confidence: 99%

“…Reactors were fed with premixed and shredded substrate, resembling the composition of the feed used in the original biogas reactor and consisting of (dry weight) maize silage (42.7%), cow manure (37.4%), and dried poultry manure (19.9%). Also, 2.5 g of this mix as well as 0.4 ml of recirculate obtained from the original biogas reactor material were added to the biogas reactor every sampling day, as previously described (Refai et al, 2014b). After sampling and feeding, the headspace of the reactors was flushed with N 2 /CO 2 (50/50) for 10 min, and incubation was continued at 40°C.…”

Section: Methodsmentioning

confidence: 99%

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Immediate Effects of Ammonia Shock on Transcription and Composition of a Biogas Reactor Microbiome

et al. 2019

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The biotechnological process of biogas production from organic material is carried out by a diverse microbial community under anaerobic conditions. However, the complex and sensitive microbial network present in anaerobic degradation of organic material can be disturbed by increased ammonia concentration introduced into the system by protein-rich substrates and imbalanced feeding. Here, we report on a simulated increase of ammonia concentration in a fed batch lab-scale biogas reactor experiment. Two treatment conditions were used simulating total ammonia nitrogen concentrations of 4.9 and 8.0 g/L with four replicate reactors. Each reactor was monitored concerning methane generation and microbial composition using 16S rRNA gene amplicon sequencing, while the transcriptional activity of the overall process was investigated by metatranscriptomic analysis. This allowed investigating the response of the microbial community in terms of species composition and transcriptional activity to a rapid upshift to high ammonia conditions. Clostridia and Methanomicrobiales dominated the microbial community throughout the entire experiment under both experimental conditions, while Methanosarcinales were only present in minor abundance. Transcription analysis demonstrated clostridial dominance with respect to genes encoding for enzymes of the hydrolysis step (cellulase, EC 3.2.1.4) as well as dominance of key genes for enzymes of the methanogenic pathway (methyl-CoM reductase, EC 2.8.4.1; heterodisulfide reductase, EC 1.8.98.1). Upon ammonia shock, the selected marker genes showed significant changes in transcriptional activity. Cellulose hydrolysis as well as methanogenesis were significantly reduced at high ammonia concentrations as indicated by reduced transcription levels of the corresponding genes. Based on these experiments we concluded that, apart from the methanogenic archaea, hydrolytic cellulose-degrading microorganisms are negatively affected by high ammonia concentrations. Further, Acholeplasma and Erysipelotrichia showed lower abundance under increased ammonia concentrations and thus might serve as indicator species for an earlier detection in order to counteract against ammonia crises.

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Section: Resultssupporting

confidence: 84%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Immediate Effects of Ammonia Shock on Transcription and Composition of a Biogas Reactor Microbiome

et al. 2019

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“…With the advent of yeast biochemical pathways for fermentation and with sophisticated temperature control equipment such as freezers, heaters, and thermometers, a plethora of new investigations has been conducted 34–59. Liquor temperature control is increasingly necessary for beer production.…”

Section: Introductionmentioning

confidence: 99%

Modeling and Control of Beer Fermentation for Optimal Flavor and Performance

Yerolla

Harsha

et al. 2023

Chem Eng & Technol

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Beer has been consumed for millennia and fermentation is crucial to the brewing process. The process requires bacteria, yeast, and carbohydrates. The temperature has the most significant influence on the beer quality as the fermentation temperature affects the fruitiness and acidity. In this work, a growth and a taste model are built for the beer fermentation process. The dynamic model simulation findings are compared and validated with industry data reported in the literature. The temperature must be regulated to maintain the consistency and flavor of the beer. The dynamic model determines the optimal controller settings for maximizing energy efficiency. To get the optimal taste profile, the proportional‐integral/proportional‐integral‐derivative controller is used to obtain optimal temperature control.

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BEAP profiles as rapid test system for status analysis and early detection of process incidents in biogas plants

Refai¹,

Berger²,

Wassmann³

et al. 2017

Journal of Industrial Microbiology and Biotechnology

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A method was developed to quantify the performance of microorganisms involved in different digestion levels in biogas plants. The test system was based on the addition of butyrate (BCON), ethanol (ECON), acetate (ACON) or propionate (PCON) to biogas sludge samples and the subsequent analysis of CH formation in comparison to control samples. The combination of the four values was referred to as BEAP profile. Determination of BEAP profiles enabled rapid testing of a biogas plant's metabolic state within 24 h and an accurate mapping of all degradation levels in a lab-scale experimental setup. Furthermore, it was possible to distinguish between specific BEAP profiles for standard biogas plants and for biogas reactors with process incidents (beginning of NH-N inhibition, start of acidification, insufficient hydrolysis and potential mycotoxin effects). Finally, BEAP profiles also functioned as a warning system for the early prediction of critical NH-N concentrations leading to a drop of CH formation.

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Increase of methane formation by ethanol addition during continuous fermentation of biogas sludge

Cited by 6 publications

References 23 publications

Immediate Effects of Ammonia Shock on Transcription and Composition of a Biogas Reactor Microbiome

Immediate Effects of Ammonia Shock on Transcription and Composition of a Biogas Reactor Microbiome

Modeling and Control of Beer Fermentation for Optimal Flavor and Performance

BEAP profiles as rapid test system for status analysis and early detection of process incidents in biogas plants

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