Use of near infrared spectroscopy in monitoring of volatile fatty acids in anaerobic digestion

Recently biogas production from agricultural sources has rapidly developed. Therefore the demands on biogas plants to optimise the efficiency of the anaerobic digestion (AD) process have grown immensely. At present there is no online-supervision tool available to monitor the AD process, but costly and time-consuming chemical analyses are necessary. The possibility to use near-infrared spectroscopy (NIRS) in order to track relevant process parameters like total volatile fatty acids (VFA), acetic acid and propionic acid was investigated in the present research project. A NIR-sensor was integrated into a full-scale 1 MW biogas plant and NIR-spectra of the fermenter contents were recorded semi-continuously for 500 days. Weekly samples were taken and analysed for the above mentioned parameters. Calibration models were calculated, capable of following these parameters: VFA (r2=0.94), acetic acid (r2=0.69), propionic acid (r2=0.89).

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Toxicity of pH, Ammonia and Volatile Fatty Acids on Hydrogenotrophic Methanogen-Enriched Sludge

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.955-959.527 ◽

2014 ◽

Vol 955-959 ◽

pp. 527-531

Author(s):

Jian Zheng Li ◽

Yu Peng Zhang ◽

Chong Liu ◽

Ze Yu Tang

Keyword(s):

Fatty Acids ◽

Acetic Acid ◽

Anaerobic Digestion ◽

Propionic Acid ◽

Butyric Acid ◽

Volatile Fatty Acids ◽

Batch Experiments ◽

Inhibitory Effects ◽

Hydrogenotrophic Methanogen ◽

The Impact

The activities of methanogen are easily affected by inhibitory substances and lead to anaerobic digestion failure. To investigate inhibitory effects on methanogenesis of a methanogen-enriched sludge, pH, volatile fatty acids (such as acetic acid, propionic acid and butyric acid), and ammonia were used as inhibitory factors and a L16(45) orthogonal table was employed to design batch experiments. The result of variance analyses shows that pH has the greatest impact on the methanogenesis of the enriched culture. The impact of butyrate, NH3, acetate and propionate was decreased in order. DGGE finger-print shows that there was only one methanogen in the inoculum sludge.

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Transflexive Embedded near Infrared Monitoring for Key Process Intermediates in Anaerobic Digestion/Biogas Production

Journal of Near Infrared Spectroscopy ◽

10.1255/jnirs.719 ◽

2007 ◽

Vol 15 (2) ◽

pp. 123-135 ◽

Cited By ~ 33

Author(s):

Jens Bo Holm-Nielsen ◽

Helga Andree ◽

Harald Lindorfer ◽

Kim H. Esbensen

Keyword(s):

Fatty Acids ◽

Anaerobic Digestion ◽

Volatile Fatty Acids ◽

Method Development ◽

Near Infrared ◽

Anaerobic Fermentation ◽

Biogas Production ◽

Total Volatile ◽

Bulk Volume ◽

Infrared Monitoring

This work reports an off-line method development simulating at-line anaerobic co-digestion process monitoring using a new transflexive embedded near infrared sensor (TENIRS) system as a process analytical chemistry (PAC) facility. The operative focus is on optimising anaerobic digestion biogas production with energy crops as the main feedstock. Results show that several key monitoring intermediates in the anaerobic fermentation process can be quantified directly using near infrared spectroscopy with good results, especially ammonium and total volatile fatty acids. Good feasibility study prediction validations have been obtained for total solids (TS), volatile solids (VS), ammonium, acetic acid and total volatile fatty acids. The TENIRS system is a new option for real-time, at-line/on-line monitoring of biogas fermentation operations, offering a robust, low-budget PAC approach to a rapidly growing bulk volume industry.

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Pilot Study of the Effects of Polyphenols from Chestnut Involucre on Methane Production, Volatile Fatty Acids, and Ammonia Concentration during In Vitro Rumen Fermentation

Animals ◽

10.3390/ani11010108 ◽

2021 ◽

Vol 11 (1) ◽

pp. 108

Author(s):

Yichong Wang ◽

Sijiong Yu ◽

Yang Li ◽

Shuang Zhang ◽

Xiaolong Qi ◽

...

Keyword(s):

Fatty Acids ◽

Acetic Acid ◽

Propionic Acid ◽

Acid Content ◽

Volatile Fatty Acids ◽

Rumen Fermentation ◽

Gas Production ◽

Quadratic Response ◽

In Vitro Rumen Fermentation

Nutritional strategies can be employed to mitigate greenhouse emissions from ruminants. This article investigates the effects of polyphenols extracted from the involucres of Castanea mollissima Blume (PICB) on in vitro rumen fermentation. Three healthy Angus bulls (350 ± 50 kg), with permanent rumen fistula, were used as the donors of rumen fluids. A basic diet was supplemented with five doses of PICB (0%–0.5% dry matter (DM)), replicated thrice for each dose. Volatile fatty acids (VFAs), ammonia nitrogen concentration (NH3-N), and methane (CH4) yield were measured after 24 h of in vitro fermentation, and gas production was monitored for 96 h. The trial was carried out over three runs. The results showed that the addition of PICB significantly reduced NH3-N (p < 0.05) compared to control. The 0.1%–0.4% PICB significantly decreased acetic acid content (p < 0.05). Addition of 0.2% and 0.3% PICB significantly increased the propionic acid content (p < 0.05) and reduced the acetic acid/propionic acid ratio, CH4 content, and yield (p < 0.05). A highly significant quadratic response was shown, with increasing PICB levels for all the parameters abovementioned (p < 0.01). The increases in PICB concentration resulted in a highly significant linear and quadratic response by 96-h dynamic fermentation parameters (p < 0.01). Our results indicate that 0.2% PICB had the best effect on in-vitro rumen fermentation efficiency and reduced greenhouse gas production.

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Study of Polyunsaturated Fatty Acids in Cheeses Using Near-Infrared Spectroscopy: Influence of Milk from Different Ruminant Species

Food Analytical Methods ◽

10.1007/s12161-020-01928-8 ◽

2021 ◽

Author(s):

Iris Lobos-Ortega ◽

Miriam Hernández-Jiménez ◽

María Inmaculada González-Martín ◽

José Miguel Hernández-Hierro ◽

Isabel Revilla ◽

...

Keyword(s):

Fatty Acids ◽

Infrared Spectroscopy ◽

Polyunsaturated Fatty Acids ◽

Near Infrared Spectroscopy ◽

Near Infrared ◽

Ruminant Species

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Enhancing near infrared spectroscopy models to identify omega-3 fish oils used in the nutraceutical industry by means of calibration range extension

Journal of Near Infrared Spectroscopy ◽

10.1177/0967033518795811 ◽

2018 ◽

Vol 26 (4) ◽

pp. 245-261 ◽

Cited By ~ 2

Author(s):

Sanette van der Merwe ◽

Marena Manley ◽

Merrill Wicht

Keyword(s):

Fatty Acids ◽

Gas Chromatography ◽

Infrared Spectroscopy ◽

Polyunsaturated Fatty Acids ◽

Near Infrared Spectroscopy ◽

Standard Error ◽

Near Infrared ◽

Fish Oils ◽

Omega 3 ◽

Alternative Method

The high demand for omega-3 fish oil nutraceuticals (dietary supplements) is due to the numerous health benefits contributed by the polyunsaturated fatty acids. The nutraceutical industry is required to follow good manufacturing practice standards in order to ensure label claims and prevent adulteration. It is vital that the quality control procedures will be able to detect adulterated products. It is thus necessary to ensure that the analytical techniques are adequate by using validated methods. The qualification or identification of natural fish oils is a difficult task due to overlapping concentration ranges of polyunsaturated fatty acids and other similar properties. Gas chromatography is the prescribed technique in the nutraceutical industry for analysis of omega-3 fatty acids, but it is time-consuming and costly. Near infrared spectroscopy is a rapid and cost-effective technique which can replace the prescribed method if it is proven to be equivalent, through validation, to the criteria as prescribed by the pharmacopoeias and other industry guidelines. In this study, near infrared spectroscopy in combination with chemometrics was considered as an alternative method to gas chromatography to identify various commercial fish oils and to quantify the polyunsaturated fatty acids. Identification methods were developed for nine commercial omega-3 fish oils by using spectral libraries. Quantitative near infrared methods were developed for arachidonic acid, docosahexaenoic acid and eicosapentaenoic acid in fish oils expressed as mg.g−1 as well as % area using partial least squares regression and independent validation by superimposing datasets with mutual properties. Based on the statistics in terms of standard error of calibration, R2, standard error of prediction and r of the polyunsaturated fatty acid models, the near infrared method was equivalent to the prescribed gas chromatography methods, and precision results obtained were also within the prescribed criteria. Near infrared spectroscopy and chemometrics can be used for conclusive identification and quantification of omega-3 fish oils, thereby minimizing the risk of adulteration. The method also complied with the prescribed pharmaceutical method validation criteria, and therefore was proven as an alternative method to gas chromatography for the nutraceutical industry.

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Enhanced lipid production by Yarrowia lipolytica cultured with synthetic and waste-derived high-content volatile fatty acids under alkaline conditions

Biotechnology for Biofuels ◽

10.1186/s13068-019-1645-y ◽

2020 ◽

Vol 13 (1) ◽

Cited By ~ 7

Author(s):

Ruiling Gao ◽

Zifu Li ◽

Xiaoqin Zhou ◽

Wenjun Bao ◽

Shikun Cheng ◽

...

Keyword(s):

Fatty Acids ◽

Acetic Acid ◽

Propionic Acid ◽

Yarrowia Lipolytica ◽

Butyric Acid ◽

Lipid Content ◽

Volatile Fatty Acids ◽

Lipid Production ◽

Initial Ph ◽

Alkaline Conditions

Abstract Background Volatile fatty acids (VFAs) can be effective and promising alternate carbon sources for microbial lipid production by a few oleaginous yeasts. However, the severe inhibitory effect of high-content (> 10 g/L) VFAs on these yeasts has impeded the production of high lipid yields and their large-scale application. Slightly acidic conditions have been commonly adopted because they have been considered favorable to oleaginous yeast cultivation. However, the acidic pH environment further aggravates this inhibition because VFAs appear largely in an undissociated form under this condition. Alkaline conditions likely alleviate the severe inhibition of high-content VFAs by significantly increasing the dissociation degree of VFAs. This hypothesis should be verified through a systematic research. Results The combined effects of high acetic acid concentrations and alkaline conditions on VFA utilization, cell growth, and lipid accumulation of Yarrowia lipolytica were systematically investigated through batch cultures of Y. lipolytica by using high concentrations (30–110 g/L) of acetic acid as a carbon source at an initial pH ranging from 6 to 10. An initial pH of 8 was determined as optimal. The highest biomass and lipid production (37.14 and 10.11 g/L) were obtained with 70 g/L acetic acid, whereas cultures with > 70 g/L acetic acid had decreased biomass and lipid yield due to excessive anion accumulation. Feasibilities on high-content propionic acid, butyric acid, and mixed VFAs were compared and evaluated. Results indicated that YX/S and YL/S of cultures on butyric acid (0.570, 0.144) were comparable with those on acetic acid (0.578, 0.160) under alkaline conditions. The performance on propionic acid was much inferior to that on other acids. Mixed VFAs were more beneficial to fast adaptation and lipid production than single types of VFA. Furthermore, cultures on food waste (FW) and fruit and vegetable waste (FVW) fermentate were carried out and lipid production was effectively improved under this alkaline condition. The highest biomass and lipid production on FW fermentate reached 14.65 g/L (YX/S: 0.414) and 3.20 g/L (YL/S: 0.091) with a lipid content of 21.86%, respectively. By comparison, the highest biomass and lipid production on FVW fermentate were 11.84 g/L (YX/S: 0.534) and 3.08 g/L (YL/S: 0.139), respectively, with a lipid content of 26.02%. Conclusions This study assumed and verified that alkaline conditions (optimal pH 8) could effectively alleviate the lethal effect of high-content VFA on Y. lipolytica and significantly improve biomass and lipid production. These results could provide a new cultivation strategy to achieve simple utilizations of high-content VFAs and increase lipid production. Feasibilities on FW and FVW-derived VFAs were evaluated, and meaningful information was provided for practical applications.

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Studies on the production of volatile fatty acids from grass by rumen liquor in an artificial rumen: II. The volatile fatty acid production from dried grass

The Journal of Agricultural Science ◽

10.1017/s0021859600036157 ◽

1957 ◽

Vol 49 (2) ◽

pp. 171-179 ◽

Cited By ~ 4

Author(s):

A. John ◽

G. Barnett ◽

R. L. Reid

Keyword(s):

Fatty Acids ◽

Acetic Acid ◽

Propionic Acid ◽

Metabolic Pathways ◽

Volatile Fatty Acid ◽

Volatile Fatty Acids ◽

Water Soluble ◽

Fatty Acid Production ◽

Growing Seasons ◽

Titration Curves

1. A study has been made of the production of volatile fatty acids obtainable from dried grass and its gross water-soluble and water-insoluble separates, in the artificial rumen, over two growing seasons.2. In contradistinction to fresh grass, the dried grass gives a consistent production of acetic acid proportionately greater than propionic acid, at all stages of maturity, but when aqueous extracts of the dried grass, and the resultant extracted grass, respectively, are examined separately in the artificial rumen, it is found that the former yield preponderating amounts of acetic acid while the latter give amounts of propionic acid equal to, or exceeding, the corresponding productions of acetic acid.3. An examination of the titration curves for the total acids obtained from the dried grass, extracted grass and grass extract runs, indicates an approach to an incomplete relationship between the residual carbohydrate in the extracted grass and cellulose, while the grass extract reveals itself as the chief source of acetic acid in the whole dried grass, the acid being formed very speedily at the start of the run.4. The suggested sources and some of the possible metabolic pathways involved in the formation of v.f.a. from grass are discussed in the text.

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Impact of Alkaline Pretreatment to Enhance Volatile Fatty Acids (VFAs) Production from Rice Husk

Biochemistry Research International ◽

10.1155/2019/8489747 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Qian Fang ◽

Sinmin Ji ◽

Dingwu Huang ◽

Zhouyue Huang ◽

Zilong Huang ◽

...

Keyword(s):

Fatty Acids ◽

Acetic Acid ◽

Propionic Acid ◽

Butyric Acid ◽

Rice Husk ◽

Volatile Fatty Acids ◽

Alkaline Pretreatment ◽

Rice Husks ◽

Acid Fermentation ◽

Study Results

This study explores the use of alkaline pretreatments to improve the hydrolyzation of rice husks to produce volatile fatty acids (VFAs). The study investigated the effects of reagent concentration and pretreatment time on protein, carbohydrates, and dissolved chemical oxygen demand (SCOD) dissolution after the pretreatment. The optimum alkaline pretreatment conditions were 0.30 g NaOH (g VS)−1, with a reaction time of 48 h. The experimental results show that when comparing the total VFA (TVFA) yields from the alkaline-pretreated risk husk with those from the untreated rice husk, over 14 d and 2 d, the maximum value reached 1237.7 and 716.0 mg·L−1 with acetic acid and propionic acid and with acetic acid and butyric acid, respectively. After the alkaline pretreatment, TVFAs increased by 72.9%; VFA accumulation grew over time. The study found that alkaline pretreatment can improve VFA yields from rice husks and transform butyric acid fermentation into propionic acid fermentation. The study results can provide guidelines to support the comprehensive utilization of rice husk and waste treatment.

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