Relevant bibliographies by topics / Volatile fatty acids

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Academic literature on the topic 'Volatile fatty acids'

Author: Grafiati
Published: 4 June 2021
Last updated: 9 June 2025

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Journal articles on the topic "Volatile fatty acids"

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Chughtai, Muhammad Farhan Jahangir, Imran Pasha, Faqir Muhammad Anjum, and Muhammad Adnan Nasir. "Characterization of Sorghum and Millet with Special Reference to Fatty Acid and Volatile Profile." Turkish Journal of Agriculture - Food Science and Technology 3, no. 7 (June 7, 2015): 515. http://dx.doi.org/10.24925/turjaf.v3i7.515-521.283.

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Sorghum and millet are important food staples in semi-arid tropics of Asia and Africa. Sorghum and millet are cereal grains that have prospective to be used as substitute to wheat flour for celiac patients. These are considered as the good source of many important and essential fatty acids. The volatile profiling of these two important crops is comparable to other cereals as well. The present study was an effort to explore biochemical composition of commercially available sorghum and millet varieties with special reference to their fatty acid and volatile profiling. Chemical composition of sorghum and millet was determined according to respective methods. Fatty acid methyl esters were prepared and then subjected to GC-FID for fatty acids analysis. The results indicated that both sorghum and millet oils are rich in essential fatty acids comprising mono and polyunsaturated fatty acids. Main fatty acids that are identified in current study includes palmitic acid, oleic acid, palmitoleic acid, behenic acid, linoleic acid, linoleic acid, stearic acid, myristic acid, etc. On the other hand volatile compounds from sorghum and millet were determined by preparing their respective volatile samples by using calvenger apparatus with suitable volatile extracting solvent. Volatile samples were then subjected to GC-MS analysis and respected results were compared with NIST library. About 30 different volatiles were identified in millet varieties while 35 different compounds were discovered in sorghum varieties belonging to aldehydes, ketones, benzene derivatives, esters, alcohols, sulphur compounds.
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Khrisanapant, Kebede, Leong, and Oey. "A Comprehensive Characterisation of Volatile and Fatty Acid Profiles of Legume Seeds." Foods 8, no. 12 (December 6, 2019): 651. http://dx.doi.org/10.3390/foods8120651.

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Legumes are rich in unsaturated fatty acids, which make them susceptible to (non) enzymatic oxidations leading to undesirable odour formation. This study aimed to characterise the volatile and fatty acid profiles of eleven types of legumes using headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS) and GC coupled with a flame ionisation detector (GC-FID), respectively. Volatile aldehydes, alcohols, ketones, esters, terpenes and hydrocarbons were the chemical groups identified across all the legumes. The lipids comprised palmitic, stearic, oleic, linoleic and α-linolenic acids, with unsaturated fatty acids comprising at least 66.1% to 85.3% of the total lipids for the legumes studied. Multivariate data analysis was used to compare volatile and fatty acid profiles between legumes, which allow discriminant compounds pertinent to specific legumes to be identified. Results showed that soybean, chickpea and lentil had distinct volatile and fatty acid profiles, with discriminating volatiles including lactone, ester and ketone, respectively. While all three Phaseolus cultivars shared similar volatile profiles, 3-methyl-1-butanol was found to be the only volatile differentiating them against the other eight legumes. Overall, this is the first time a multivariate data analysis has been used to characterise the volatile and fatty acid profiles across different legume seeds, while also identifying discriminating compounds specific for certain legume species. Such information can contribute to the creation of legume-based ingredients with specific volatile characteristics while reducing undesirable odours, or potentially inform relevant breeding programs.
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Wang, Zhiwei, Weiwu Wang, Ping Li, Yaping Leng, and Jinhua Wu. "Continuous Production of Volatile Fatty Acids (VFAs) from Swine Manure: Determination of Process Conditions, VFAs Composition Distribution and Fermentation Broth Availability Analysis." Water 14, no. 12 (June 16, 2022): 1935. http://dx.doi.org/10.3390/w14121935.

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For pollution control and waste utilization, a promising future direction is to obtain high-value carbon sources from organic waste. In this experiment, swine manure was efficiently converted into high concentration volatile fatty acids through continuous hydrolysis-acidification bioreactors. This study determined the process conditions, the composition distribution of volatile fatty acids and the availability of fermentation broth. The results showed that the reactor with a hydraulic retention time of 1.5 days had the optimal production performance of volatile fatty acids. The highest hydrolysis degree (62.2%) and acidification degree (42.5%) were realized in this reactor at the influent soluble chemical oxygen demand of 5460 mg/L. Furthermore, when the influent soluble chemical oxygen demand was 7660 mg/L, volatile fatty acids of 6065 mg-COD/L could be produced stably, and the proportion of volatile fatty acids in soluble chemical oxygen demand was the largest (75%). Additionally, the fermentation broth rich in volatile fatty acids could be applied to deep nitrogen and phosphorus removal. This work provides a productive approach to resource recovery from swine manure.
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van der Wielen, Paul W. J. J., Steef Biesterveld, Len J. A. Lipman, and Frans van Knapen. "Inhibition of a Glucose-Limited Sequencing Fed-Batch Culture ofSalmonella enterica Serovar Enteritidis by Volatile Fatty Acids Representative of the Ceca of Broiler Chickens." Applied and Environmental Microbiology 67, no. 4 (April 1, 2001): 1979–82. http://dx.doi.org/10.1128/aem.67.4.1979-1982.2001.

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ABSTRACT The effects of concentrations of volatile fatty acids on an anaerobic, glucose-limited, and pH-controlled growing culture ofSalmonella enterica serovar Enteritidis were studied. Suddenly increasing volatile fatty acids to the concentrations representative of the ceca of 15-day-old broiler chickens caused washout of serovar Enteritidis. In contrast, a sudden increase to the volatile fatty acid concentrations representative of the ceca of younger broiler chickens caused a reduction in the biomass but not washout. Gradually increasing volatile fatty acids caused a gradual decrease in the biomass of serovar Enteritidis. We conclude that the concentrations of volatile fatty acids present in the ceca of broilers with a mature microflora can cause washout of serovar Enteritidis in an in vitro system mimicking cecal ecophysiology.
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Rahim, Ahmad Fitri Abd, Shamsul Rahman Mohamed Kutty, and Ezerie Henry Ezechi. "Volatile Fatty Acids Production through Degradation of Biomass by Anaerobic Digestion (Mesophilic and Thermophilic)." Applied Mechanics and Materials 567 (June 2014): 172–76. http://dx.doi.org/10.4028/www.scientific.net/amm.567.172.

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Volatile fatty acids (VFAs) are fatty acids with a carbon chain of six carbons or fewer and usually referred to as short-chain fatty acids (SCFA). Degradation of biomass through anaerobic digestion will produce volatile fatty acid (VFAs) through anaerobic digestion process. The volatile fatty acids obtained can be recovered and used to produce methyl or ethyl esters which, could be advantageously used as additive for biodiesel [1]. Anaerobic digestion is a biological process that can degrade waste organic material by concerted action of a wide range of microorganisms in the absence of oxygen. The objective of this study is to degrade the biomass through anaerobic digestion for the production of volatile fatty acids by two different temperatures condition which are mesophilic and thermophilic; 35°C and 55°C respectively. The production of volatile fatty acids was optimized by varying the cycle period of the digestion process with the concentration of Mixed Liquor Suspended Solid (MLSS) maintained at 8000 mg/L for each cycle. The degradation of biomass was carried out using anaerobic sludge digester which 2L of biomass was digested from day 1 until day 24 (cycle period). The tests of MLSS and Mixed Liquor Volatile Suspended Solid (MLVSS) was conducted by Standard Method 2540-D while test for VFAs was conducted through Standard Method 8196. The highest production of volatile fatty acids was obtained in day 5 of cycle period where the concentration is 441 mg/L as acetic acid (HOAC).
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Kim, J. O., I. Somiya, E. B. Shin, W. Bae, S. K. Kim, and R. H. Kim. "Application of membrane-coupled anaerobic volatile fatty acids fermentor for dissolved organics recovery from coagulated raw sludge." Water Science and Technology 45, no. 12 (June 1, 2002): 167–74. http://dx.doi.org/10.2166/wst.2002.0423.

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To investigate the treatment performance of membrane-coupled anaerobic volatile fatty acids fermentor system, the effects of operational parameters for volatile fatty acids production were evaluated through experiments and a mathematical model. The volatile fatty acids recovery ratio was largely affected by the change of hydraulic retention time, reaching its maximum value at 12 hrs. Over the range of hydraulic retention time 8 to 96 hrs, the volatile fatty acids recovery ratio decreased with the increase of hydraulic retention time above 12 hrs, while the ratio of mineralization and gasification increased. Hydraulic retention time and membrane filtration ratio should be maintained less than 1 day and above 0.9, respectively, to attain over 40% of organic materials recovery ratio at 10 days of solids retention time. When the hydrolysis rate constant was 0.01 hr−1, the organic loading rate should be maintained at above 1.0 (kgC/m3/day) to attain over 45% of volatile fatty acids recovery ratio. Based on experimental and simulated results, membrane-coupled anaerobic volatile fatty acids fermentor system was thought to be effective for dissolved organics recovery from coagulated sewage sludge.
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Hu, Xianqiao, Changyun Fang, Lin Lu, Zhanqiang Hu, Weixing Zhang, and Mingxue Chen. "Dynamic Changes in Volatiles, Soluble Sugars, and Fatty Acids in Glutinous Rice during Cooking." Foods 12, no. 8 (April 19, 2023): 1700. http://dx.doi.org/10.3390/foods12081700.

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Cooking is an important process before rice is consumed and constitutes the key process for rice flavor formation. In this paper, dynamic changes in aroma- and sweetness-related compounds were tracked during the entire cooking process (including washing with water, presoaking, and hydrothermal cooking). The volatiles, fatty acids, and soluble sugars in raw rice, washed rice, presoaked rice, and cooked rice were compared. After being washed with water, the total volatiles decreased while aldehydes and unsaturated fatty acids increased. Meanwhile, oligosaccharides decreased and monosaccharides increased. The changes in fatty acids and soluble sugars caused by the presoaking process were similar to those in the water-washing process. However, different changes were observed for volatiles, especially aldehydes and ketone. After hydrothermal cooking, furans, aldehydes, alcohols, and esters increased while hydrocarbons and aromatics decreased. Moreover, all fatty acids increased; among these, oleic acids and linoleic acid increased most. Unlike with washing and presoaking, all soluble sugars except fructose increased after hydrothermal cooking. Principal component analysis showed that cooked rice possessed a volatile profile that was quite different from that of uncooked rice, while washed rice and presoaked rice possessed similar volatile profiles. These results indicated that hydrothermal cooking is the pivotal process for rice flavor formation.
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Borowski, Sebastian, and Marcin Kucner. "The use of sugar beet pulp stillage for co-digestion with sewage sludge and poultry manure." Waste Management & Research 37, no. 10 (April 10, 2019): 1025–32. http://dx.doi.org/10.1177/0734242x19838610.

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The anaerobic mesophilic co-digestion of sugar beet pulp stillage with poultry manure and municipal sewage sludge was investigated in this study. The sugar beet pulp stillage (SBPS) mono-digestion failed owing to an accumulation of volatile fatty acids, leading to a pH value lower than 5.5. A 20% addition of poultry manure to stillage allowed for stable digestion performance despite high volatile fatty acid (total volatile fatty acids) concentrations of 5500–8500 g m−3 with propionic acid being the predominant one and constituting 72%–76% total volatile fatty acids. For this mixture, the maximum methane production of 418 dm3 kgVSfed−1 was achieved when the reactor was operated at a solids retention time of 20 days and an organic loading rate of 4.25 kgVS m−3 d−1. The co-digestion of stillage with 60% municipal sewage sludge gave the average methane yield of around 357 dm3 kgVSfed−1 for all operational conditions applied, however, the methane percentage of biogas (up to 70%) was far greater than the corresponding values obtained for sugar beet pulp stillage–poultry manure co-digestion. Neither ammonia nor volatile fatty acids destabilised the biogas production, and the volatile fatty acid profile showed the dominance of acetic acid (72%–82% total volatile fatty acids) followed by propionic and butyric acids.
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Wajs-Bonikowska, Anna, Karol Olejnik, Radosław Bonikowski, and Piotr Banaszczak. "Analysis of Volatile Components, Fatty Acids, and Phytosterols of Abies Koreana growing in Poland." Natural Product Communications 8, no. 9 (September 2013): 1934578X1300800. http://dx.doi.org/10.1177/1934578x1300800928.

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Extracts and essential oils from seeds as well as essential oils from cone scales and needles with twigs of the Abies koreana population were studied. An analysis of Korean fir essential oils allowed us to determine 147 volatile compounds. The identified compounds constituted 97–99% of the seed, cone and needle oils. The main volatile in the seed and needle oils was limonene (56.6% and 23.4%, respectively), while the predominant volatile in cone oils was α-pinene (51.2%). Korean fir seeds provided a rich source of both essential oil (3.8–8.5%) and extract, which was isolated with a 24.5% yield and contained numerous groups of fatty acids and phytosterols (414 μg/100g extract). The most prominent fatty acids were unsaturated, among which linoleic (41.2%) and oleic (31.2%) fatty acid were the main ones while the dominant sterols were isomers of ergostadienol and β-sitosterol. A. koreana seeds, cones and needles are a source of many volatile bioactive compounds while the seed extract, with a pleasant scent, contained not only volatiles, but also fractions rich in fatty acids and phytosterols. These facts make A. koreana essential oils and especially the seed extract potential components of cosmetics.
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Najdoska-Bogdanov, Menče, Jane B. Bogdanov, and Marina Stefova. "Simultaneous Determination of Essential Oil Components and Fatty Acids in Fennel using Gas Chromatography with a Polar Capillary Column." Natural Product Communications 10, no. 9 (September 2015): 1934578X1501000. http://dx.doi.org/10.1177/1934578x1501000933.

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Cultivated and wild growing samples of fennel ( Foeniculum vulgare Mill., Apiaceae) from R. Macedonia were studied for their volatiles and fatty acid composition. The main essential oil components isolated via hydrodistillation were: trans-anethole (>80%), estragole (<6%), limonene (<6%), anisaldehyde (<1%) and 0.5 % fenchone. An alternative method for characterization of both the non-polar volatile and non volatile fractions was developed using n-hexane and dichloromethane (3:1, v/v) in a Soxhlet extraction followed by transesterification. The obtained extracts were then characterized and the dominant fatty acid was 18:1 (petroselinic and oleic acid) 75.0–82.8 %, followed by 18:2 (linoleic acid) 10.8–16.2% and other fatty acids: palmitic (4.3–6.9%), stearic (1.2–1.7%) and myristic (0–2.9%). The results for the volatile fraction after Soxhlet extraction and transesterification did not significantly differ from results obtained after hydrodistillation, especially for the main components ( trans-anethole, estragole, fenchone and limonene), implying that the developed method can be used for simultaneous determination of volatiles and fatty acids.
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Dissertations / Theses on the topic "Volatile fatty acids"

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Abouzreba, Salem Ali. "Volatile fatty acids in the ambient atmosphere." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388115.

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Ghimire, Sandip. "Volatile Fatty Acid Production in Ruminants." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/75306.

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Volatile fatty acids (VFA) are important products of ruminal fermentation. The VFA are not only the major source of energy to the ruminant animals but also influence methane production in the rumen. Therefore it is important to understand mechanism controlling VFA production and to depict VFA production in a model. This will allow us to devise strategies to enhance energy utilization and reduce methane production in ruminant livestock. An evaluation of a mechanistic model in predicting VFA production was conducted and equations were introduced into the model to improve the predictions. Later a continuous culture experiment was conducted to test the hypothesis on which those equations were based on. A mechanistic model -" Molly, was evaluated using a dataset with reported VFA production rates. The results of residual error analysis indicated that the root mean square prediction errors (RMSPE) were 63, 63, and 49% for acetate, propionate and butyrate, respectively. An assessment from two studies reporting VFA production revealed a potential of reducing errors of prediction by representing interconversion among VFA. In the second study, equations based on thermodynamics influence of pH and VFA concentration were introduced in the model to represent interconversion among VFA. The parameters for de novo VFA production and VFA absorption were re derived with (VFAInt) and without (BASE) the new interconversion equations. There were some improvements in the VFA concentration predictions but the improvements were both in VFAInt and BASE models. The RMSPE of VFA production were still above 50% for acetate, propionate and butyrate. The larger errors of predictions were attributed to measurement variation in VFA production literature, or possible incorrect rate constants for interconversion equations. Finally, a third study was conducted to assess the effect of pH, and VFA concentration on VFA and methane production in continuous culture. The treatments consisted of control, 20 mmol/d acetate infusion (INFAC), 7 mmol/d propionate infusion (INFPR), and low pH (LOWPH). Individual isotopes of acetate, propionate and butyrate were infused in the fermenters to estimate interconversions among VFA. With LOWPH treatment methane emission was reduced whereas production of propionate was increased. Hydrogen production was higher in INFAC indicating that some of the acetate could have been degraded to CO2 and H2. It was estimated that around 3 % of de novo acetate was converted to propionate and 9 % to butyrate. Exchange between propionate and butyrate was insignificant and below 1% of de novo production of either VFA. However, treatments did not affect interconversion rates among VFA. These results indicated that pH and VFA concentration do not have thermodynamic influence on VFA interconversion as hypothesized.<br>Ph. D.
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Caunt, P. "Degradation of volatile fatty acids by immobilised bacteria." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233711.

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The aims of this project were to study the immobilisation of microorganisms and the use of immobilised cell preparations in biochemical reactors. One particular process, the biodegradation of volatile fatty acids (VFAs), was chosen as a model system. Volatile fatty acids are compounds which are commonly found in odorous wastes and so can present a pollution problem. A bacterium was isolated, which was capable of VFA degradation in a minimal medium. The organism was identified as a strain of Alcaligenes denitrificans. The strain was able to grow on, and degrade, individual straight chain VFAs and mixtures, at concentrations much higher than those used in the isolation conditions. The strain was found to grow at a wide range of pH values, and a moderately wide range of growth temperatures. The strain was also tested for the degradation of VFAs in piggery slurry, but was found to be less effective than the natural population of organisms present in the waste. This bacterium was used to assess various immobilisation techniques, and their suitability for use in bioreactors. Four gel entrapment systems were tested. Conventional polyacrylamide and aluminium alginate gels both resulted in loss of cell viability. Calcium alginate was found to be too fragile for use in bioreactors, and only polyacrylamide hydrazide gel was found to be suitable. Beads of polyacrylamide hydrazide were used for longer term operation in a bubble column reactor, in a series of experiments to study the effects of changes in operating conditions, on bioreactor efficiency. Mathematical correlations were developed to explain the effects. Other parameters such as the mass transfer coefficients were calculated, to assist in the prediction of scale up. The second immobilisation system tested was adsorption to inorganic matrices. Four different types of particle were tested for their ability to adsorb non-growing cells from solution. The capacity to adsorb cells was related to the surface properties of the particles. Celite diatomaceous earth particles were found to have the greatest capacity to adsorb cells. Celite beads could be seeded in this manner, and then operated in a bubble column bioreactor. A biofilm was formed on the beads, which was capable of steady state biodegradation when the reactor was operated at dilution rates above the theoretical maximum for free cell growth. Bubble columns were the most suitable reactor of those tested for use with immobilised cell preparations. Mixing in these reactors was sufficient to provide good mass transfer, but not so violent as to disrupt the immobilised cell particles. Cell immobilisation by adsorption onto Celite was found to have several advantages over the other systems tested. The matrix could adsorb large quantities of cells, resulting in rapid biofilm formation and was also relatively cheap. Therefore, this appears to be an excellent new technique, and its potential applications in industrial processes are discussed.
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Ganesan, Balasubramanian. "Catabolism of Amino acids to Volatile Fatty Acids by Lactococcus lactis." DigitalCommons@USU, 2005. https://digitalcommons.usu.edu/etd/5509.

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Lactic acid bacteria are essential as flavor producers of cheese and fermented products. They are capable of catabolizing aromatic, branched chain, and sulfur amino acids to flavor compounds. During cheese ripening the numbers of lactococcal colonies decrease, but lactococci survive without replication in culture. This prompted an investigation into possible mechanisms of catabolism of branched chain amino acids into branched chain fatty acids and the physiological relevance of amino acid catabolism to the bacteria. We hypothesized that lactococci catabolize branched chain amino acids to branched chain fatty acids during nonculturability. Lactococci, lactobacilli, and brevibacteria catabolized both branched chain amino acids and keto acids into branched chain fatty acids. Lactococci survived carbohydrate-limited conditions for over 4 yrs. Their survival was represented by maintaining intracellular ATP, enzyme activity, membrane integrity, capability of ATP- and PMF-dependent substrate transport, transcription, and catabolism of amino acids to fatty acids. Assays conducted with NMR spectroscopy coupled with in silico analysis showed that branched chain substrates are catabolized via keto acids, HMG-CoA, and acetyl-CoA to branched chain fatty acids. A short list of candidate genes was identified for the pathway by gene expression analysis coupled to NMR analysis. The expression of these genes and the presence of the related catabolites were identified in long-term starved cultures of nonculturable lactococci. This verified that catabolism of branched chain amino acids to branched chain fatty acids occurred during the nonculturable state only and in conditions of carbohydrate deprivation. The pathway also facilitated fixation of carbon by lactococci, revealing the mechanism of survival of lactococci over 4 yrs in culture without the addition of external carbon sources. Between strains the availability of carbohydrate and acid stress played significant roles in modulating their ability to produce branched chain catabolites. The ability of lactococci to catabolize branched chain amino acids during sugar starvation represents a shift in carbon catabolic routes. The identified pathway also represented a balance between catabolism and anabolism, suggesting that the bacteria were in a homeostatic state during nonculturability. We accepted the hypothesis that nonculturable lactococci catabolized branched chain amino acids to branched chain fatty acids during starvation./p>
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Long, Jennifer Erin. "Optimization of volatile fatty acids production in full-scale fermenters." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0018/MQ48064.pdf.

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Passanha, Pearl. "Improved polyhydroxyalkanoate production from selected volatile fatty acids using Cupriavidus necator." Thesis, University of South Wales, 2014. https://pure.southwales.ac.uk/en/studentthesis/improved-polyhydroxyalkanoate-production-from-selected-volatile-fatty-acids-using-cupriavidus-necator(18bc71e1-1514-4c4c-afe7-8d53ff23b0a1).html.

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This study aimed to develop methods to improve PHA production from selected volatile fatty acids (VFAs) and to improve the understanding of the PHA production process by pure culture bacterial fermentation using Cupriavidus necator. Optimisation strategies involved the following investigations using shake flasks and 5 litre based batch fermentations: Shake flask investigations determined that the temperature of 30oC and a nutrient medium, resulted in the highest growth of bacteria. A feeding strategy of the substrate (VFAs - acetic acid and butyric acid) was developed to avoid inhibition by the substrate and the alkaline buffer. The results established that continuous feeding of VFAs based on maintaining optimum pH around 7 resulted in enhanced PHA yields by almost 2-fold when compared to single pulse feeding of acetic and butyric acids (at 1, 2, 3, 4 and 5 g/l VFA concentration). A novel application of a capacitance probe was demonstrated to be able to monitor maximum PHA accumulation in-situ and in real-time, so as to prevent product and substrate loss (acetic and butyric acids, by a maximum value of 12 g/l and 20 g/l respectively), and to increase PHA process understanding and fermentation kinetics. The dielectric spectroscopy probe was able to correlate very well (R2 = 0.862) with PHA off-line measurements when operated in dual frequency mode and was able to establish the optimum PHA harvesting time, which would have resulted in improved process economics and environmental performance. Shake flask experiments were conducted to investigate the addition of trace metals (zinc, manganese, boric acid, cobalt, nickel and sodium molybdate), copper and sodium chloride in nutrient media and its effects on bacteria growth. NaCl contributed to the greatest enhancement in the early growth of bacteria and therefore fed batch fermentations using 0, 3.5, 6.5, 9, 12 and 15 g/l of additional NaCl concentrations were evaluated. The 9 g/l NaCl concentration showed the highest PHA production of 5.33 g/l and also caused PHA accumulation to occur earlier by 2 h than the control. The capacitance probe also helped visualise and understand the bacterial growth and PHA accumulation profile. The novel use of low cost digestates based media was demonstrated. Results demonstrated that possibly due to the nutrients/trace elements in a digestate (from food wastes and wheat feed) the PHA accumulation was enhanced by 3-fold (to 12.29 g/l); with a resulting highest ever reported PHA accumulation of 90% for C. necator. C: N: K: P: S ratios for this digestate based fermentation were found to be for growth 761: 31: 1: 3.5: 1.9 and for PHA accumulation 1132: 11: 3: 1.7: 1. Digestates use within biotechnology and biorefining specifically for bacterial applications could provide another alternative route to digestate disposal that may lead to valuable end products. All the above evaluations represented novelty and have delivered significant process optimisation for PHA production from VFAs.
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McPeak, David W. (David William). "The behavior of volatile fatty acids in model solutions during freeze-drying /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65359.

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Teiseh, Eliasu Azinyui. "Anaerobic hydrogen production by photosynthetic purplenonsulfur [sic] bacteria using volatile fatty acids." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1594490411&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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Chakraborty, Sagar Ph D. Massachusetts Institute of Technology. "Exploring volatile fatty acids (VFAs) as a novel substrate for microbial oil production." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98701.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references.<br>Cost effective production of biofuels depends critically on feedstock cost and availability. As such, volatile fatty acids (VFAs) can play an important role in advancing sustainable biofuel production since they can be derived from low cost feedstock including gases and municipal solid waste. To this end, we studied fermentations of the oleaginous microbe Yarrowia lipolytica engineered for lipid overproduction. With acetate as sole carbon source, we conducted fed batch fermentations of Y. lipolytica in which acetic acid was maintained at low, non-inhibitory levels yielding high lipid titer of 50 g/L and productivity of 0.25 g/L/h, along with a lipid content of 60%. We also conducted fed batch fermentations with cell recycle to utilize dilute steams of acetic acid that essentially replicated the results of the fed batch process. Carbon balances were satisfied and no excess carbon dioxide production was detected beyond the amounts associated with biomass formation and product synthesis. Acetate is one member of the entire range of VFAs produced from municipal solid waste (MSW) via anaerobic digestion; thus, facilitating the use of MSW as a primary feedstock would be contingent on the ability of the above strain to grow on a mixture of VFAs. Given the insufficient literature examining microbial growth on VFAs, one of the goals of this project was to explore individual as well as mixed VFAs as a feedstock for Y.lipolytica. Dilute stream of mixed VFAs were successfully used as feed in bioreactor studies to obtain high cell density cultures. Similar results with respect to lipid production were obtained in comparison to the study on acetate. In addition, the microbe could tolerate perturbations in the feed composition and grow to similar cell densities. The success in establishing VFAs as a potential substrate for lipid accumulation in Yarrowia lipolytica raises the possibility of a two-stage commercial bioprocess enabling biodiesel production from MSW.<br>by Sagar Chakraborty.<br>Ph. D.
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Abegg, Richard. "Volatile fatty acids in digesta samples of cows with spontaneous cecal dilatation/dislocation /." [S.l.] : [s.n.], 1998. http://www.stub.unibe.ch/html/haupt/datenbanken/diss/bestell.html.

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Books on the topic "Volatile fatty acids"

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Hughes, Raymond Hickman. Absorption of Soluble Volatile Fatty Acids. Creative Media Partners, LLC, 2021.

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Dept.of Environment. Titrimetric Determination of Total and Bicarbonate Alkalinity and Volatile Fatty Acids in Sewage Sludge, 1980-89. Stationery Office Books, 1989.

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Ansari, Mohammed N. a. Effect of Particle Size, Heating and Pelleting of Rations on Volatile Fatty Acids Production in the Rumen of Lambs. Creative Media Partners, LLC, 2021.

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Book chapters on the topic "Volatile fatty acids"

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Asadi, Fateme, Fatemeh Nouri, and Mohammad Taheri. "Microbial Processing on Agri-wastes to Volatile Fatty Acids." In Microbial Bioprocessing of Agri-food Wastes, 27–68. Boca Raton: CRC Press, 2023. http://dx.doi.org/10.1201/9781003128977-2.

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Anoopkumar, Ammini Naduvanthar, Embalil Mathachan Aneesh, Aravind Madhavan, Raveendran Sindhu, Mukesh Kumar Awasthi, Ashok Pandey, Laya Liz Kuriakose, and Parameswaran Binod. "Volatile Fatty Acids Production and Recovery in Biohydrogen Production." In Biofuel and Biorefinery Technologies, 389–401. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-49818-3_15.

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Park, Gwon W., Nag-Jong Kim, and Ho Nam Chang. "Microbial Lipid Production from Volatile Fatty Acids by Oleaginous Yeast." In Emerging Areas in Bioengineering, 203–13. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2018. http://dx.doi.org/10.1002/9783527803293.ch12.

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Thennakoon, H. M. K. S. B., S. M. W. T. P. K. T. Ariyarathne, and M. Danthurebandara. "Monitoring Volatile Fatty Acids in an Anaerobic Process with Microbial Fuel Cell." In Lecture Notes in Civil Engineering, 288–94. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-9749-3_27.

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Protozoa, Rumen Ciliate, Kevin Hillman, Alan G. Williams, and David Lloyd. "Effects of Various Headspace Gases on the Production of Volatile Fatty Acids." In Microbiology and Biochemistry of Strict Anaerobes Involved in Interspecies Hydrogen Transfer, 395–97. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4613-0613-9_43.

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Yano, Takuo, Pakorn Nuchnoi, Naomichi Nishio, and Shiro Nagai. "Extraction of Volatile Fatty Acids from Spent Medium with a Supported Liquid Membrane." In Bioproducts and Bioprocesses, 281–93. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-74227-9_26.

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Rafiq Kumar, M., S. M. Tauseef, Tasneem Abbasi, and S. A. Abbasi. "Generation of Volatile Fatty Acids (VFAs) from Dried and Powdered Ipomoea (Ipomoea carnea)." In Advances in Health and Environment Safety, 169–92. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-7122-5_18.

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Rafiq Kumar, M., S. M. Tauseef, Tasneem Abbasi, and S. A. Abbasi. "Conversion of Volatile Fatty Acids (VFAs) Obtained from Ipomoea (Ipomoea carnea) to Energy." In Advances in Health and Environment Safety, 269–78. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-7122-5_28.

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Pinares-Patiño, C. S., H. Kjestrup, S. MacLean, E. Sandoval, G. Molano, R. Harland, S. Hickey, et al. "Methane emission from sheep is related to concentrations of rumen volatile fatty acids." In Energy and protein metabolism and nutrition in sustainable animal production, 495–96. Wageningen: Wageningen Academic Publishers, 2013. http://dx.doi.org/10.3920/978-90-8686-781-3_183.

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Moreroa, Mabatho, Diane Hildebrandt, and Tonderayi Matambo. "Aerobic Bioremediation of Fischer-Tropsch Effluent – Short Chain Alcohols and Volatile Fatty Acids." In Transactions on Engineering Technologies, 209–18. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-6848-0_17.

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Conference papers on the topic "Volatile fatty acids"

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(Randy) Nixon, Robert A. "Upset Conditions in Anaerobic Distgers in Wastewater Treatment Plants Cause Degradation of Protective Linings." In CONFERENCE 2022, 1–11. AMPP, 2022. https://doi.org/10.5006/c2022-18235.

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Abstract Both mesophilic and thermophilic anaerobic digesters are currently being utilized to treat sludge derived from more than typical municipal sewerage sources. Wastewater treatment plants are accepting septage and sludge from food waste and industrial contributors routinely today. Receiving these other sources of waste which are extremely high in volatile solids is a source of significant income for the utilities. However, high volatile solids loading into the digesters can cause out-of-balance biochemical conditions in the digesters. High volatile fatty acid to alkalinity ratios and low methane production are but a few of the repercussions of these imbalanced conditions. These process upsets result in high acetic, propionic and other intermediate fatty acids. These exposures, when sufficiently prolonged, can cause degradation to the polymers in some protective coating systems commonly used successfully in the past. This paper will present evidence of this type of attack based on both field experience and laboratory testing data. Recommendations will be made for future material selection criteria and testing to avoid premature lining failures in anaerobic digesters in the future.
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Farquhar, Gale B. "A Review and Update of the Role of Volatile Fatty Acids (Vfa’S) in Seawater Injection Systems." In CORROSION 1998, 1–11. NACE International, 1998. https://doi.org/10.5006/c1998-98005.

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Abstract This paper presents a current review and update of the role the presence of volatile fatty acids play in the production problems related to sea water injection. Such production problems as corrosion, formation souring, deep water subsea injectivity and decline in injectivity are discussed. Conceptual souring models, methods of sampling and analysing for VFA and modern research methods developed towards VFA related sea water injection systems are reviewed. Areas for future research are indicated..
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Kharshan, Margarita, and Alla Furman. "Incorporating Vapor Corrosion Inhibitors (VCIS) in Oil and Gas Pipeline Additive Formulations." In CORROSION 1998, 1–10. NACE International, 1998. https://doi.org/10.5006/c1998-98236.

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Abstract Two new oil and gas pipeline additives were formulated utilizing volatile corrosion inhibitors (VCIs). These products provide a very high level of protection for steel subjected to different types of corrosive petrochemicals due to surface adsorption and vapor phase action environments. The formulation work was based on fatty acid imidazoline chemistry combined with different organic acids. Different surfactants were used to provide maximum wetting properties to the inhibitor and faster transport of inhibitor from the oil or gas phase to the water. Vapor corrosion inhibitors were introduced in the formulation. A Windows-compatible software was used to identify the vital factors that affect the quality of the product. The protective properties of newly developed inhibitors were evaluated in various types of corrosive mediums.
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Baird, Crawford, Dora Ogles, and Brett R. Baldwin. "Molecular Microbiological Methods to Investigate Microbial Influenced Corrosion in Fully Integrated Kraft Pulp and Paper Mills." In CORROSION 2016, 1–11. NACE International, 2016. https://doi.org/10.5006/c2016-07278.

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Abstract MIC often contributes to corrosion in paper mills despite the seemingly inhospitable conditions for microbial growth. Molecular microbiological methods most notably quantitative polymerase chain reaction (qPCR) were employed to examine MIC at three paper mills with unique operations and construction materials. Despite raw water treatment, qPCR quantification of total bacteria and specific MIC associated microbial groups revealed growth of substantial and diverse microbial populations which had not been identified with cultivation based methods. Moreover, qPCR quantification of several microbial groups highlighted their roles in MIC. At most facilities including one experiencing corrosion of UNS S31254, iron oxidizing bacteria (IOB) were detected at high concentrations (1.00 × 108 cells/g). The actions of IOB were confirmed by x-ray diffraction analysis demonstrating production of iron oxyhydroxides (e.g. hematite). Fermenting bacteria were also routinely detected. Along with direct impacts, volatile fatty acids and hydrogen produced during fermentation support growth of other anaerobic microorganisms linked to MIC. Consistent with tubercle formation and biofilm maturation, sulfate reducing bacteria (SRB) and methanogens were detected in some solid phase samples. Overall, the qPCR results suggest biomass growth within the system, IOB activity and tubercle formation followed by proliferation of fermenters and eventually SRB and methanogens under the deposits.
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Tanji, Yasunori, Kazuya Toyama, and Kazuhiko Miyanaga. "Identification of Crude Oil Component Which Facilitate Biological Souring." In CORROSION 2014, 1–13. NACE International, 2014. https://doi.org/10.5006/c2014-3853.

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Abstract Seawater injection into oil reservoirs for secondary oil recovery is frequently accompanied by souring (increased sulfide concentrations). Production of hydrogen sulfide causes various problems, such as microbiologically influenced corrosion (MIC), deterioration of crude oil. Sulfate-reducing bacteria (SRB) are considered to be major players in souring. Volatile fatty acids (VFAs) in oil field water are assumed to be produced by microbial degradation of crude oil. The objective of this research is to investigate mechanisms of souring from the view of VFA production by the crude oil biodegradation. A microbial consortium collected from oil-water separator was suspended to seawater. Crude oil or liquid n-alkane mixture was added to the culture medium as sole carbon source. Anaerobic incubation was conducted for 190 days. Physicochemical analysis showed that preferable toluene degradation and sulfate reduction occurred concomitantly in crude oil amended condition. Sulfide concentration was much lower in alkane mixture amended condition than that of crude oil amended condition. These observations suggest that SRB are related to toluene activation and VFA consumption steps in crude oil degradation. Therefore, the electron donors for SRB were not only VFA, but a lot of crude oil components, especially toluene. Alkanes were also degraded by microorganisms, but did not so contribute to reservoir souring.
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Lillebø, Bente-Lise P., Terje Torsvik, Egil Sunde, and Hans Kristian Hornnes. "Effect of Water Content on the Growth of Srb in Crude Oil." In CORROSION 2010, 1–9. NACE International, 2010. https://doi.org/10.5006/c2010-10206.

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Abstract Growth of sulfate reducing bacteria (SRB) in crude oil, with variable amounts of enrichment medium was studied. Gullfaks, Snorre and Grane crude oil were used as carbon and energy source. In Gullfaks crude oil anaerobic cultures with 2 to 95 % v/v brine were inoculated with a mixed culture of SRB and incubated at 30 C for 4 weeks. The cultures were amended with volatile fatty acids (VFA) to enhance growth of SRB. Cultures were analyzed for growth of SRB and H2S production. Growth of SRB was observed in cultures with 6 % water and more, and H2S production was observed in cultures with 10 % water and more. In cultures without VFA H2S production was not observed. In Snorre and Grane crude oil anaerobic cultures with 2 to 10 % v/v enrichment medium were inoculated with a mixed culture of SRB and incubated at 30 C for 4 weeks. Half of the cultures were amended with VFA to enhance growth of SRB; the other half contained only crude oil as carbon and energy source. In cultures grown on crude oil from Snorre, with or without VFA, no growth of SRB or sulfide production was observed. In contrast, growth of SRB and H2S production was observed in all cultures with crude oil from Grane, regardless the water amount and whether acids were added or not. Chemical analysis of the crude oil showed major differences in oil composition with regards to the lighter oil components. Snorre oil contained 23 % Wt of oil compounds lighter than C10, while Gullfaks and Grane oil contained 9.7 and 2.9 % Wt respectively. The light oil fraction also contains the most water soluble components, including benzene and toluene known to be toxic to many bacteria, including SRB. Since a typical export specification for crude oil is less than 0.5 % water, the results from Gullfaks and Snorre (light crude oil) showed that growth of SRB in transport pipelines was strongly inhibited under these conditions. In cultures with crude oil from Grane, a heavier crude oil, growth of SRB was observed even at 2 % water content.
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Maxwell, Stephen. "Implications of Re-Injection of Produced Water on Microbially Influenced Corrosion (MIC) in Offshore Water Injection Systems." In CORROSION 2005, 1–9. NACE International, 2005. https://doi.org/10.5006/c2005-05549.

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Abstract Historically, pressure maintenance on many offshore oil production fields has been achieved by the injection of treated seawater. With increasing environmental awareness, however, a zero discharge policy is now becoming the norm and this requires the re-injection of produced water as a means of avoiding overboard dumping. Unfortunately, however, the mixing of seawater and produced water can result in several potential problem scenarios with regard to water quality, scaling tendency, injectivity losses and corrosion control. Microbiological activity is implicit in some of these problems and it is essential, therefore, that the microbiological impact of mixing these waters should be considered. In general, produced water containing residual oil and other organic nutrients (e.g. volatile fatty acids) provides a significantly greater source of organic carbon than seawater. Additionally, produced water is often contaminated with sulfate-reducing bacteria (SRB), which are growing throughout the oily water separation system. Numbers of 103 – 106 SRB per ml are not uncommon in produced water, many orders of magnitude greater than the &amp;lt; 1 SRB per litre typical in open seawater. This has led many to believe that the mixing of re-injected produced water and seawater is a recipe for disaster and will result in increased incidences of MIC and reservoir souring. Often it is taken as inevitable, therefore, that very significant volumes of biocide chemicals will be required to control SRB growth in such situations in order to minimise the potential for MIC. Whilst in certain ratios the mixing of seawater and some produced waters may result in 'ideal' conditions for SRB growth, this is not always the case. This paper describes the considerable variability in SRB growth and activity in mixtures of seawater and produced water dependant upon mixing ratios, salinity and temperature conditions. The paper discusses how an understanding of the microbiology of the produced water, seawater and mixtures of both can indicate the potential risk of MIC being enhanced and thereby allow a more cost effective biocide treatment to be developed.
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Leleika, Scott, Taylor Rambo, and Tekle Fida. "Effects of Renewable Natural Gas and Hydrogen on Microbially Influenced Corrosion and Souring in Underground Gas Storage." In CONFERENCE 2024, 1–15. AMPP, 2024. https://doi.org/10.5006/c2024-21146.

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Abstract A bench scale laboratory experiment was conducted to assess the microbial corrosion and souring effects renewable natural gas (RNG) and natural gas amended with hydrogen have on underground gas storage systems. Steel coupon-containing vials inoculated with produced fluid from an underground storage well were subject to different headspace conditions to simulate underground gas storage. The vials were filled with geologic natural gas, geologic natural gas amended with hydrogen, RNG, and RNG amended with hydrogen. Each condition was subject to molecular (qPCR, and 16S rRNA analysis), liquid chemistry (sulfate and volatile fatty acid), corrosion, and headspace chemistry (major components and trace sulfur) analysis in duplicate at three time points. The results showed that levels of sulfide production, microbial community composition, and coupon mass loss did not differ greatly between the natural gas and RNG conditions. However, the presence of hydrogen did increase the levels of sulfide in both geologic and RNG conditions. There was also evidence of significant biotransformation of hydrogen into an organic acid (formate). This experiment has shown that microbes native to underground storage wells could have an impact on gas quality and corrosion (via hydrogen sulfide production) if hydrogen is introduced.
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Hoffmann, Heike, Kevin Harris, and Jim Palmer. "The Laboratory Evaluation of Seawater Injection on H2S Production, Incorporating Several Different Treatment Strategies, Utilizing Fixed Film Upflow Bioreactors." In CORROSION 2014, 1–15. NACE International, 2014. https://doi.org/10.5006/c2014-3861.

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Abstract Reservoir Souring is the unplanned production of increased concentrations of hydrogen sulfide (H2S) in well-stream fluids from production wells that are subjected to water-injection. The consequences of souring with respect to safety, corrosion and environmental risk can be significant. This is typically associated with the activity of a specialized group, the Sulfate-reducing bacteria (SRB). However, in recent years, various other micro-organisms are believed to be involved in souring, e.g. Sulfate reducing archaea (SRA). In this study, fixed film up flow bioreactors (FFUBR) were utilized to assess the potential for H2S production or changes in such H2S production, when seawater is injected into a North Sea oil reservoir. The study has demonstrated how changes in fundamental parameters (e.g. bacterial nutrients, shut-in periods) can impact sulfide production and alter the microbial communities. The FFUBR’s were soured to create a ‘worst case’ scenario and different nutrient additions or remediation treatments were applied to represent either near injection wellbore or deep field conditions. Typical oil field practice is to measure H2S in the gas phase. Partition modelling of H2S between water, oil and gas phase was applied to the measured sulfide data to give a real-world indication of the effect of H2S in gas when resuming production following a shut-in. The following parameters were measured during the testing period: sulfide generation, volatile fatty acid organic carbon sources (VFA), iron, nitrate and nitrite concentrations. The microbiology of the system was evaluated both by traditional culture techniques and molecular methods, such as fluorescence in situ hybridization (FISH) analysis and other DNA-based analysis. Results indicate that when sulfide generation had reached 1.5 mM, and the nutrient source was changed, almost complete cessation of sulfide generation resulted for a period of 7 days. Whereas, following shut-in period, sulfide generation recommenced after re-starting the flow and reached a concentration of 4.4 mM immediately and rose even higher to 5.0 mM over the first days of flow. However, sulfide concentrations returned to 2.0 mM again within 7 days after restart. However, the changes in the microbial community were found to be somewhat selective to certain SRB families. The various effects of the different treatments and conditional changes are discussed further in this paper.
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Yun, Jung Hyun, and Beom Soo Kim. "Production of Polyhydroxyalkanoates by Ralstonia Eutropha from Volatile Fatty Acids." In 14th Asia Pacific Confederation of Chemical Engineering Congress. Singapore: Research Publishing Services, 2012. http://dx.doi.org/10.3850/978-981-07-1445-1_204.

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Reports on the topic "Volatile fatty acids"

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Koziel, Jacek, Yael Laor, Jeffrey Zimmerman, Robert Armon, Steven Hoff, and Uzi Ravid. Simultaneous Treatment of Odorants and Pathogens Emitted from Confined Animal Feeding Operations (CAFOs) by Advanced Oxidation Technologies. United States Department of Agriculture, January 2009. http://dx.doi.org/10.32747/2009.7592646.bard.

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A feasibility study was conducted, aiming to explore the potential effectiveness of UV/TiO2/O3 photooxidation technologies for simultaneous treatment of odorant and pathogen emissions from livestock and poultry operations. Several key parameters were tested in laboratory (US) and semi-pilot (Israel) scale conditions including: the effects of light energy dose (treatment time and light intensity), relative humidity and air temperature, UV wavelength, presence of photocatalyst (TiO2) and the presence of ozone. Removal and conversion of odor, target gases (sulfur-containing volatile organic compounds S-VOCs, volatile fatty acids (VFAs), phenolics, and ammonia), and airborne pathogens was tested. Up to 100% removal (below method detection level) of S-VOCs, VFAs, and phenolics, the overall odor, and up to 64.5% of ammonia was achieved with optimized treatment. Treatments involving deep UV band (185 nm) and photocatalyst (TiO2) were more efficient in removal/conversion of odorous gases and odor. The estimate of the operational cost of treatment was based on measured emissions of several odorous VOCs from full scale, commercial swine farm ranges from $0.15 to $0.59 per finisher pig. This figure represents significantly lower cost compared with the cost of biofiltration or air scrubbing.
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Asvapathanagul, Pitiporn, Leanne Deocampo, and Nicholas Banuelos. Biological Hydrogen Gas Production from Food Waste as a Sustainable Fuel for Future Transportation. Mineta Transportation Institute, July 2022. http://dx.doi.org/10.31979/mti.2021.2141.

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In the global search for the right alternative energy sources for a more sustainable future, hydrogen production has stood out as a strong contender. Hydrogen gas (H2) is well-known as one of the cleanest and most sustainable energy sources, one that mainly yields only water vapor as a byproduct. Additionally, H2 generates triple the amount of energy compared to hydrocarbon fuels. H2 can be synthesized from several technologies, but currently only 1% of H2 production is generated from biomass. Biological H2 production generated from anaerobic digestion is a fraction of the 1%. This study aims to enhance biological H2 production from anaerobic digesters by increasing H2 forming microbial abundance using batch experiments. Carbon substrate availability and conversion in the anaerobic processes were achieved by chemical oxygen demand and volatile fatty acids analysis. The capability of the matrix to neutralize acids in the reactors was assessed using alkalinity assay, and ammonium toxicity was monitored by ammonium measurements. H2 content was also investigated throughout the study. The study's results demonstrate two critical outcomes, (i) food waste as substrate yielded the highest H2 gas fraction in biogas compared to other substrates fed (primary sludge, waste activated sludge and mixed sludge with or without food waste), and (ii) under normal operating condition of anaerobic digesters, increasing hydrogen forming bacterial populations, including Clostridium spp., Lactococcus spp. and Lactobacillus spp. did not prolong biological H2 recovery due to H2 being taken up by other bacteria for methane (CH4) formation. Our experiment was operated under the most optimal condition for CH4 formation as suggested by wastewater operational manuals. Therefore, CH4-forming bacteria possessed more advantages than other microbial populations, including H2-forming groups, and rapidly utilized H2 prior to methane synthesis. This study demonstrates H2 energy renewed from food waste anaerobic digestion systems delivers opportunities to maximize California’s cap-and-trade program through zero carbon fuel production and utilization.
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Asvapathanagul, Pitiporn, Leanne Deocampo, and Nicholas Banuelos. Biological Hydrogen Gas Production from Food Waste as a Sustainable Fuel for Future Transportation. Mineta Transportation Institute, July 2022. http://dx.doi.org/10.31979/mti.2022.2141.

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In the global search for the right alternative energy sources for a more sustainable future, hydrogen production has stood out as a strong contender. Hydrogen gas (H2) is well-known as one of the cleanest and most sustainable energy sources, one that mainly yields only water vapor as a byproduct. Additionally, H2 generates triple the amount of energy compared to hydrocarbon fuels. H2 can be synthesized from several technologies, but currently only 1% of H2 production is generated from biomass. Biological H2 production generated from anaerobic digestion is a fraction of the 1%. This study aims to enhance biological H2 production from anaerobic digesters by increasing H2 forming microbial abundance using batch experiments. Carbon substrate availability and conversion in the anaerobic processes were achieved by chemical oxygen demand and volatile fatty acids analysis. The capability of the matrix to neutralize acids in the reactors was assessed using alkalinity assay, and ammonium toxicity was monitored by ammonium measurements. H2 content was also investigated throughout the study. The study's results demonstrate two critical outcomes, (i) food waste as substrate yielded the highest H2 gas fraction in biogas compared to other substrates fed (primary sludge, waste activated sludge and mixed sludge with or without food waste), and (ii) under normal operating condition of anaerobic digesters, increasing hydrogen forming bacterial populations, including Clostridium spp., Lactococcus spp. and Lactobacillus spp. did not prolong biological H2 recovery due to H2 being taken up by other bacteria for methane (CH4) formation. Our experiment was operated under the most optimal condition for CH4 formation as suggested by wastewater operational manuals. Therefore, CH4-forming bacteria possessed more advantages than other microbial populations, including H2-forming groups, and rapidly utilized H2 prior to methane synthesis. This study demonstrates H2 energy renewed from food waste anaerobic digestion systems delivers opportunities to maximize California’s cap-and-trade program through zero carbon fuel production and utilization.
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Lee, E. J., and Dong U. Ahn. Production of Volatiles from Fatty Acids and Oils by Irradiation. Ames (Iowa): Iowa State University, January 2004. http://dx.doi.org/10.31274/ans_air-180814-1038.

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Weinberg, Zwi G., Richard E. Muck, Nathan Gollop, Gilad Ashbell, Paul J. Weimer, and Limin Kung, Jr. effect of lactic acid bacteria silage inoculants on the ruminal ecosystem, fiber digestibility and animal performance. United States Department of Agriculture, September 2003. http://dx.doi.org/10.32747/2003.7587222.bard.

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The overall objective of the whole research was to elucidate the mechanisms by which LAB silage inoculants enhance ruminant performance. The results generated will permit the development of better silage inoculants that maximize both silage preservation and animal performance. For this one-year BARD feasibility study, the objectives were to: 1. determine whether lactic acid bacteria (LAB) used in inoculants for silage can survive in rumen fluid (RF) 2.select the inoculants that survived best, and 3. test whether LAB silage inoculants produce bacteriocins-like substances. The most promising strains will be used in the next steps of the research. Silage inoculants containing LAB are used in order to improve forage preservation efficiency. In addition, silage inoculants enhance animal performance in many cases. This includes improvements in feed intake, liveweight gain and milk production in 25-40% of studies reviewed. The cause for the improvement in animal performance is not clear but appears to be other than direct effect of LAB inoculants on silage fermentation. Results from various studies suggest a possible probiotic effect. Our hypothesis is that specific LAB strains interact with rumen microorganisms which results in enhanced rumen functionality and animal performance. The first step of the research is to determine whether LAB of silage inoculants survive in RF. Silage inoculants (12 in the U.S. and 10 in Israel) were added to clarified and strained RF. Inoculation rate was 10 ⁶ (clarified RF), 10⁷ (strained RF) (in the U.S.) and 10⁷, 10⁸ CFU ml⁻¹ in Israel (strained RF). The inoculated RF was incubated for 72 and 96 h at 39°C, with and without 5 g 1⁻¹ glucose. Changes in pH, LAB numbers and fermentation products were monitored throughout the incubation period. The results indicated that LAB silage inoculants can survive in RF. The inoculants with the highest counts after 72 h incubation in rumen fluid were Lactobacillus plantarum MTD1 and a L. plantarum/P. cerevisiae mixture (USA) and Enterococcus faecium strains and Lactobacillus buchneri (Israel). Incubation of rumen fluid with silage LAB inoculants resulted in higher pH values in most cases as compared with that of un-inoculated controls. The magnitude of the effect varied among inoculants and typically was enhanced with the inoculants that survived best. This might suggest the mode of action of LAB silage inoculants in the rumen as higher pH enhances fibrolytic microorganisms in the rumen. Volatile fatty acid (VFA) concentrations in the inoculated RF tended to be lower than in the control RF after incubation. However, L. plalltarull1 MTDI resulted in the highest concentrations of VFA in the RF relative to other inoculants. The implication of this result is not as yet clear. In previous research by others, feeding silages which were inoculated with this strain consistently enhanced animal performance. These finding were recently published in Weinberg et.al.. (2003), J. of Applied Microbiology 94:1066-1071 and in Weinberg et al.. (2003), Applied Biochemistry and Biotechnology (accepted). In addition, some strains in our studies have shown bacteriocins like activity. These included Pediococcus pentosaceus, Enterococcus faecium and Lactobacillus plantarum Mill 1. These results will enable us to continue the research with the LAB strains that survived best in the rumen fluid and have the highest potential to affect the rumen environment.
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