scholarly journals Enrichment of Homoacetogens Converting H2/CO2 into Acids and Ethanol and Simultaneous Methane Production

2021 ◽  
Author(s):  
Yaxue He ◽  
Chiara Cassarini ◽  
Piet N. L. Lens
Keyword(s):  
Acetic Acid ◽  
Butyric Acid ◽  
Methane Production ◽  
Granular Sludge ◽  
Caproic Acid ◽  
Valeric Acid ◽  
Operating Conditions ◽  
Anaerobic Sludge ◽  
Batch Tests ◽  
Ph Decrease

Abstract An anaerobic granular sludge was enriched to utilize H2/CO2 in a continuous gas-fed up-flow anaerobic sludge reactor by applying operating conditions expected to produce acetic acid, butyric acid and ethanol. Three stages of fermentation were found: Stage I with acetic acid accumulation with the highest concentration of 35 mM along with a pH decrease from initial 6 to 4.5. In Stage II, H2/CO2 was replaced by 100% H2 to induce solventogenesis, whereas butyric acid was produced with the highest concentration of 2.5 mM. At Stage III with 10 μM tungsten (W) addition, iso-valeric acid, valeric acid and caproic acid were produced at pH 4.5 -5.0. In the batch tests inoculated with the enriched sludge taken from the bioreactor (day 70), however, methane production occurred at pH 6. Exogenous 15 mM acetate addition enhanced both the H2 and CO2 consumption rate compared to exogenous 10, 30 and 45 mM acetate by the enriched sludge. Exogenous acetate failed to be converted to ethanol using H2 as electron donor by the enriched acetogens.

Fermentation in the Rumen of the Sheep

1952 ◽  
Vol 29 (1) ◽  
pp. 57-65 ◽  
Author(s):  
F. V. GRAY ◽  
A. F. PILGRIM ◽  
H. J. RODDA ◽  
R. A. WELLER
Keyword(s):  
Fatty Acids ◽  
Acetic Acid ◽  
Propionic Acid ◽  
Butyric Acid ◽  
Active Carbon ◽  
Volatile Fatty Acids ◽  
Caproic Acid ◽  
Valeric Acid ◽  
Carboxyl Group

1. The mixture of volatile fatty acids in the rumen of the sheep has been shown to include formic acid, acetic acid, propionic acid, n-butyric acid, iso-butyric acid, n-valeric acid, another valeric acid isomer, caproic acid and an acid which is probably heptoic acid. The proportions in which they are present have been determined. 2. When acetic acid labelled with 14C in the carboxyl group was incorporated in the rumen fermentation in vitro, active carbon appeared later in all the higher acids. When labelled propionic acid was included in the fermentation, active carbon appeared in the valeric but not in the butyric acid. The results suggest a synthesis of the higher acids by condensation of the lower ones with 2-C compound in equilibrium with acetic acid. The extent of such syntheses and other possible modes of origin of the fatty acids are discussed.

scholarly journals Influence of the Mediterranean diet on the production of short-chain fatty acids in women at risk for breast cancer (LIBRE)

2020 ◽  
Vol 79 (OCE2) ◽  
Author(s):  
Benjamin Seethaler ◽  
Jacqueline Beutel ◽  
Marie Kogel ◽  
Maryam Basrai ◽  
Jens Walter ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Physical Activity ◽  
Fatty Acids ◽  
Acetic Acid ◽  
Mediterranean Diet ◽  
Butyric Acid ◽  
Short Chain Fatty Acids ◽  
Valeric Acid ◽  
Short Chain ◽  
Control Group

AbstractBackground: A number of small intervention studies suggested that a Mediterranean diet (MedD) and physical activity can lower the risk for breast cancer. LIBRE is the first large multicenter RCT to test the effect of these lifestyle factors on the incidence of breast cancer in women at risk because of BRCA mutations(1). LIBRE also offers to unravel underlying mechanisms such as the role of short-chain fatty acids (SCFA) for beneficial effects of such lifestyle interventions.Methods: We examined the effect of the lifestyle intervention on the production of SCFA measured in feces by gas chromatography. From the ongoing LIBRE trial we included all complete datasets (171 women; mean age 44 ± 11 years). Both women with and without previous breast cancer diagnosis were recruited (diseased; non-diseased). The participants were randomized into an intervention group (IG) trained for MedD and physical activity, and a usual care control group (CG). Adherence to the MedD was assessed at baseline and after 3 months (V1) using the validated Mediterranean Diet Adherence Screener (MEDAS) and the EPIC food frequency questionnaire (FFQ).Results: At baseline there was no difference in SCFA levels between the groups. In the IG the MEDAS score increased substantially by 2.5 points (p < 0.001), in the CG only mildly by 0.4 points (p < 0.05). Correspondingly, the intake of fibers increased solely in the IG. In the course of the study the amount of caproic acid decreased in the control group (p < 0.001). At V1 non-diseased women showed higher amounts of acetic acid (p = 0.042), n-butyric acid (p = 0.023), n-valeric acid (p = 0.018) and iso-valeric acid (p = 0.031). There were several correlations between the intake of different fibers and fecal SCFA. For example, the sum of poly- and oligosaccharides correlated with acetic acid (p = 0.001; r = 0.316), propionic acid (p = 0.034; r = 0,251), n-butyric acid (p = 0.010; r = 0.316) and iso-valeric acid (p = 0.012; r = 0.306). There was no correlation between the MEDAS and SCFA.Discussion: A lifestyle change towards a MedD and increased physical activity did not change the levels of SCFA in feces, although an increase of fiber intake was documented in the IG. To further analyze SCFA metabolism in this target population, gut microbiota composition and function (metabolites) are currently analyzed.

Anaerobic (UASB) Treatment of Pulp (CTMP) Wastewater and the Toxicity on Granules

1991 ◽  
Vol 23 (10-12) ◽  
pp. 1919-1928 ◽  
Author(s):  
A. Kudo ◽  
K. Kennedy ◽  
E. Andras
Keyword(s):  
Acetic Acid ◽  
Carbon Source ◽  
Mercuric Chloride ◽  
Biogas Production ◽  
Removal Rate ◽  
Anaerobic Sludge ◽  
Anaerobic Culture ◽  
Batch Tests ◽  
Production Ratio ◽  
Specific Loading

A chemi-thermomechanical pulp (CTMP) effluent was treated by upflow anaerobic sludge bed (UASB) reactors. The purpose of the 254 day experiment was to evaluate the acclimatization process for two types of anaerobic granules to CTMP wastewater. One type was an acetic acid enriched culture composed mainly of methanogenic bacteria (reactor I) and the other was a mixed anaerobic culture containing both methanogenic and acidogenic bacteria (reactor II). Initially the reactors were maintained on synthetic feed with acetic acid (reactor I) or sucrose (reactor II) as the carbon source. In order to acclimatize the granules to the wastewater, CTMP wastewater was introduced in 3 stages (10, 50, and 100%). The wastewater contained 8200 mg/l COD, 30-40% of which was non-biodegradable. Both reactors were operated at a specific loading rate of 0.16 g COD/g VSS/day throughout the experiment. Supplementary batch tests using serum bottles were conducted to evaluate toxicity of the CTMP wastewater and two known toxic compounds, pentachlorophenol and mercuric chloride, on mixed anaerobic culture granules. Reactor II acclimatized to the CTMP wastewater better than reactor I. At 50% CTMP wastewater, a COD removal rate of 80% was attained for reactor II, while reactor I removed only 55% of the influent COD. Coincidentally, acetic acid consumption in reactor I was also inhibited after the introduction of 50% CTMP wastewater. It took reactor I 60 days to recover from the CTMP toxicity and to achieve the level of reactor II performance. An unexpected discovery was that the granules from both reactors were completely inhibited 2 weeks after the completion of the 254 day experiment. The granules were stored in a cold room (4°C) for two weeks, during this period, the granules lost the ability to degrade acetic acid. These sick (inhibited) granules re-gained acetoclastic activity when sucrose feed was provided as a carbon source. The results of batch tests showed a dramatic reduction in granule biogas production after exposure both to starvation and to toxicants at levels higher than a certain threshold concentration. The biogas production ratio between the starved and the fed granules was decreased from 89.9% to 43.0% when they were exposed to 50% and 300% CTMP wastewater, respectively. The toxicity of 100% CTMP was equivalent to 7 ppm of pentachlorophenol and 25 ppm of mercuric chloride.

Biosorption of Cu(II) by powdered anaerobic granular sludge from aqueous medium

2013 ◽  
Vol 68 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Xu Zhou ◽  
Chuan Chen ◽  
Aijie Wang ◽  
Guangming Jiang ◽  
Lihong Liu ◽  
...  
Keyword(s):  
Surface Area ◽  
Granular Sludge ◽  
Anaerobic Sludge ◽  
Order Kinetic ◽  
Factors Affecting ◽  
Biosorption Capacity ◽  
Biosorption Process ◽  
Batch Tests ◽  
Equilibrium Data ◽  
Order Kinetic Model

Copper(II) biosorption processes by two pre-treated powdered anaerobic granular sludges (PAGS) (original sludges were methanogenic anaerobic granules and denitrifying sulfide removal (DSR) anaerobic granules) were investigated through batch tests. Factors affecting the biosorption process, such as pH, temperature and initial copper concentrations, were examined. Also, the physico-chemical characteristics of the anaerobic sludge were analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy image, surface area and elemental analysis. A second-order kinetic model was applied to describe the biosorption process, and the model could fit the biosorption process. The Freundlich model was used for describing the adsorption equilibrium data and could fit the equilibrium data well. It was found that the methanogenic PAGS was more effective in Copper(II) biosorption process than the DSR PAGS, whose maximum biosorption capacity was 39.6% lower. The mechanisms of the biosorption capacities for different PAGS were discussed, and the conclusion suggested that the environment and biochemical reactions during the growth of biomass may have affected the structure of the PAGS. The methanogenic PAGS had larger specific surface area and more biosorption capacity than the DSR PAGS.

On Site High Rate UASB Anaerobic Demonstration Plant Treatment of NSSC Wastewater

1988 ◽  
Vol 20 (1) ◽  
pp. 87-97 ◽  
Author(s):  
L. H. A. Habets ◽  
M. H. Tielbaard ◽  
A. M. D. Ferguson ◽  
C. F. Prong ◽  
A. J. Chmelauskas
Keyword(s):  
Pilot Plant ◽  
Granular Sludge ◽  
Full Scale ◽  
Operating Conditions ◽  
High Rate ◽  
Upflow Anaerobic Sludge Blanket ◽  
Anaerobic Sludge ◽  
Study Results ◽  
Wastewater Quality ◽  
Demonstration Plant

Results of a 19 m3 demonstration plant studies are summarized. The plant is located at Sturgeon Falls at a NSSC mill and hardboard plant owned by MacMillan Bloedel. The mill discharges 6300 m3/day of waste effluent containing 50 tonnes of BOD and 127 tonnes of COD. Lab scale testing (1983) and an 18 month 1.4 m3 reactor volume pilot plant study (1985) were completed confirming treatability of the wastewater and suitability of the Upflow Anaerobic Sludge Blanket (UASB) technology among others to successfully treat the mill wastewater. Discharged effluent contains spent sulphite liquor and primary clarifier effluent. As required, the 1.4 m3 Biopaq System successfully achieved BOD reductions in excess of 75 percent at loadings greater than 10 kg COD/m3.d. As a consequence of this and because of economic considerations, the Biopaq System of Paques-Lavalin was selected for on site demonstration during a 12 months period. This period started in spring 1986. Erection of a full-scale plant is planned to take place in 1988. The purpose of the on site demonstration study is to confirm wastewater treatability, optimize design loading rates and confirm granular sludge growth. To achieve the objectives and simulate full-scale operating conditions the MacMillan Bloedel pilot plant has been automated and is controlled via a microprocessor incorporating a customized software program. Start-up performance results and operation at incremental loadings under steady state conditions are presented together with the experience gained during extreme variations in mill effluent quality and flow. Preliminary study results from the first 10 months disclose that a BOD removal efficiency of 80 percent or better is achieved at weekly average loadings of 15 kg COD/m3.d, and the process offers strong resilience to daily swings in wastewater quality. The results also show a net accumulation of granular sludge. The practical application of this technology from a mill operating perspective is discussed, and the layout for a full-scale installation with projected capital and operating costs is provided. Most of the contents of this paper was presented at the Tappi 1987 Environmental Conference (Prong etal, 1987). This paper presents the latest results.

scholarly journals Methanization potential of anaerobic biodigestion of solid food waste

2018 ◽  
Vol 22 (1) ◽  
pp. 69-73 ◽  
Author(s):  
Laís R. G. de Oliveira ◽  
Derovil A. dos Santos Filho ◽  
Kaline C. Vasconcelos ◽  
Talita V. de Lucena ◽  
José F. T. Jucá ◽  
...  
Keyword(s):  
Food Waste ◽  
Methane Production ◽  
Granular Sludge ◽  
Methanogenic Bacteria ◽  
Upflow Anaerobic Sludge Blanket ◽  
Anaerobic Sludge ◽  
Buffering Agent ◽  
Semi Solid ◽  
Unfavorable Condition ◽  
Anaerobic Sludge Blanket

ABSTRACT Anaerobic biodigestion of solid and semi-solid wastes has been widely used for the treatment of these residues and methane production; however, during the process (more specifically in the acidogenic phase), there is a tendency of pH reduction, an unfavorable condition to methanogenic bacteria. Thus, the present work aims to evaluate the methanization potential of an agroindustrial anaerobic granular sludge (AIS) from UASB (Upflow Anaerobic Sludge Blanket) reactor, individually and biodigested with food waste (FW) from the University Restaurant of the Federal University of Pernambuco with buffering agent (AIS + FW + b) and without it (AIS + FW). After the laboratory tests, the AIS + FW + b configuration obtained a cumulative methane production approximately six times greater than that of AIS + FW, and approximately twice that of the inoculum alone (AIS).

Effect of Different Operating Conditions on MFC Performance

2013 ◽  
Vol 724-725 ◽  
pp. 762-768 ◽  
Author(s):  
Shan Shan Lu ◽  
Yang Guo Zhao ◽  
Ru Liu
Keyword(s):  
Acetic Acid ◽  
Microbial Fuel Cells ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Membrane Surface ◽  
Operating Conditions ◽  
Anode Surface ◽  
Anaerobic Sludge ◽  
Buffer Solution ◽  
Seed Sludge ◽  
Aerobic Sludge

Dual-chamber microbial fuel cells (MFCs) were established to study the effect of seed sludge, carbon sources, buffering solution and stirring on power generation performance. Scanning electron microscope (SEM) and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technologies were used to investigate the spatial distribution characteristics of bacterial community. The results showed that the MFC feeding with lactic acid obtained 0.57V of electromotive force, and 1.57 W/m3 of volumetric power density. It reached 0.62V and 2.07 W/m3 when the carbon source was changed to acetic acid. Compared with anaerobic sludge, aerobic sludge had higher maximum voltage and longer high voltage duration. The stirring and the adding buffer solution improved electricity generation. SEM and DGGE profiles indicated that a large number of bacilli were tightly bound to the anode surface. Microbial community structure on the membrane surface was more similar to suspended sludge than sediment and seed sludge. In conclusion, MFCs perform better with incubating aerobic sludge, feeding acetic acid, adding PBS buffer (50mmol/L) and stirring.

scholarly journals The fermentation of soluble carbohydrates in rumen contents of cows given diets containing a large proportion of flaked maize

1969 ◽  
Vol 23 (3) ◽  
pp. 567-583 ◽  
Author(s):  
J. D. Sutton
Keyword(s):  
Acetic Acid ◽  
Propionic Acid ◽  
Butyric Acid ◽  
Volatile Fatty Acids ◽  
Valeric Acid ◽  
The Other ◽  
Soluble Carbohydrates ◽  
In Vitro Experiments

1. Studies were made of the fermentation of D-glucose, D-fructose, D-galactose, D-xylose, L-arabinose and sucrose by rumen contents from two cows fed 1 kg hay and 4 or 5 kg flaked maize once daily. The proportions of volatile fatty acids (VFA) in the rumen before addition of carbohydrates varied widely but on average acetic acid constituted about 52%, propionic acid about 29% and n-butyric acid about 13% of the total.2. In in vitro experiments, 896 mg of the monosaccharides and 851 mg sucrose were added to 150 g mixed rumen contents incubated for 2 h; the carbohydrates were added at 10 min intervals throughout the incubation on three occasions with each cow. Mean proportions of the carbohydrates fermented ranged from about 60% of the pentoses to about 85% of sucrose and glucose. Of the VFA produced from galactose and the pentoses, acetic acid constituted about 40%, propionic acid 45–55% and n-butyric acid 1–7%; very little n-valeric acid was produced. With the other carbohydrates results from the two cows differed, owing mainly to the production of appreciable amounts of n-valeric acid with one cow only. Acetic acid constituted about 40% of the VFA produced from fructose and sucrose, propionic acid 20–40%, n-butyric acid 14–22% and n-valeric acid up to 12%. The proportions of VFA produced from glucose were intermediate between the other two groups.3. Net recovery of carbon from fermented carbohydrate in VFA was about 35–45%. A further 1–6%, of fermented glucose, fructose and sucrose was recovered in lactic acid.4. In in vivo experiments, the monosaccharides only were infused into the rumen for 8 h at the rate of 200 g/h. Changes in the concentrations of substrates and products varied widely, owing to the variable basal fermentation, but changes in the proportions of VFA in the rumen were similar to those found in vitro.5. The results of the in vitro experiments were compared with those obtained in earlier experiments in which the same cows were given a diet containing 70% hay. Significant regressions (P < 0.05) were found between the molar proportions of acetic, propionic and n-valeric acids produced from the substrates and the proportions of these acids present in the rumen contents at the start of the incubations, but the relationships differed markedly among the different carbohydrates. Most of the significant regressions were positive but negative regressions for propionic acid production from fructose and sucrose with one cow suggested the existence of more complex interrelationships among two or more VFA.

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