Recovery of volatile fatty acids (VFA) from complex waste effluents using membranes

Waste effluents from anaerobic digesters of agricultural waste were treated with a range of membranes, including microfiltration and nanofiltration (NF), to concentrate volatile fatty acids (VFA). Microfiltration was applied successfully to produce sterile, particle-free solutions with a VFA concentration of 21.08 mM of acetic acid and 15.81 mM of butyric acid. These were further treated using a variety of NF membranes: NF270 (Dow Chemicals, USA), HL, DL, DK (Osmonics, USA) and LF10 (Nitto Denko, Japan), achieving retention ratios of up to 75%, and giving retentates of up to 53.94 mM of acetate and 28.38 mM of butyrate. DK and NF270 membranes were identified as the best candidates for VFA separation and concentration from these multicomponent effluents, both in terms of retention and permeate flux. When the effluents are adjusted to alkali conditions, the highest productivity, retention and flux were achieved at pH 7. At higher pH there was a significant reduction in flux.

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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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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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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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Fermentation in the Rumen of the Sheep

Journal of Experimental Biology ◽

10.1242/jeb.29.1.57 ◽

1952 ◽

Vol 29 (1) ◽

pp. 57-65 ◽

Cited By ~ 1

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.

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The relationship in the cow between milk-fat secretion and ruminal volatile fatty acids

British Journal Of Nutrition ◽

10.1079/bjn19660023 ◽

1966 ◽

Vol 20 (2) ◽

pp. 217-228 ◽

Cited By ~ 35

Author(s):

J. E. Storry ◽

J. A. F. Rook

Keyword(s):

Fatty Acids ◽

Acetic Acid ◽

Butyric Acid ◽

Milk Fat ◽

Volatile Fatty Acids ◽

General Pattern ◽

Control Period ◽

Fat Content ◽

Initial Control ◽

The Individual

1. The effect of reducing the hay and of increasing the proportions of concentrate and flaked maize in the diet of cows on the secretion of milk fat and its component fatty acids and on the proportions of volatile fatty acids in the rumen liquor has been studied. 2. The low-hay diet caused a fall in the milk fat content to about half of the values in the initial control period and the secretion of all the major fatty acids in the milk was reduced. The general pattern of change in the proportions of rumen VFA during the change to the low-hay diet was a decrease in acetic acid, an increase in propionic and n-valeric acids, relatively little change in n-butyric acid and also an increase in the concentration of lactic acid. Approximately 60% of the variation in milk fat content during the change of diet was associated with the increase in propionic acid. 3. In cows established on the low-hay diet there were marked variations in the relative proportions of acetic and propionic acids, but there was no related change in milk fat content. On return of the animals to the high-hay diet, recovery of the initial proportions of acetic, propionic and valeric acids occurred within about 4 days but the recovery in milk fat content was not complete until 2–3 weeks had elapsed. 4. Although the intraruminal infusion of acetic acid in cows on the low-hay diet caused increases and decreases respectively in the molar proportions of acetic and propionic acids in the rumen, an increase in milk fat content was observed amounting to only one-quarter of the loss associated with the transfer to the low-hay diet; therem was no characteristic pattern of increase in the yields of the individual fatty acids of milk fat. No consistent effects of intraruminal infusions of butyric acid, in cows on the low-hay diet, on the yield of milk fat or of the individual fatty acids were observed.

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The production and absorption of volatile fatty acids from the rumen of the sheep

Australian Journal of Agricultural Research ◽

10.1071/ar9680791 ◽

1968 ◽

Vol 19 (5) ◽

pp. 791 ◽

Cited By ~ 7

Author(s):

GJ Faichney

Keyword(s):

Fatty Acids ◽

Acetic Acid ◽

Butyric Acid ◽

Volatile Fatty Acids ◽

Metabolizable Energy ◽

The Other ◽

In Vitro Fermentation ◽

The Mean ◽

The Difference

Experiments are reported in which sheep were given roughage diets or a high concentrate diet and the VFA absorbed from the rumen were estimated by an in vitro fermentation procedure. The VFA absorbed were compared with the digestible and metabolizable energy intakes of the sheep, determined in digestibility trials, for each diet. For a lucerne diet, a straw diet, and the high concentrate diet the proportions of the digested energy absorbed as VFA were 33.6, 42.4, and 33.2% respectively. On the lucerne diet, the difference between the mean molar proportions of the VFA absorbed and the mean molar proportions of the VFA in the rumen approached significance for acetic acid (P < 0.10) and was highly significant for butyric acid (P < 0.01). The differences were not significant for the other diets.

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Assessment of Fatty Acids Profile and Omega-3 Polyunsaturated Fatty Acid Production by the Oleaginous Marine Thraustochytrid Aurantiochytrium sp. T66 Cultivated on Volatile Fatty Acids

Biomolecules ◽

10.3390/biom10050694 ◽

2020 ◽

Vol 10 (5) ◽

pp. 694 ◽

Cited By ~ 3

Author(s):

Alok Patel ◽

Ulrika Rova ◽

Paul Christakopoulos ◽

Leonidas Matsakas

Keyword(s):

Fatty Acids ◽

Acetic Acid ◽

Fatty Acid ◽

Butyric Acid ◽

Volatile Fatty Acids ◽

Low Cost ◽

Dry Weight ◽

Total Lipids ◽

Omega 3 ◽

Fatty Acid Production

Thraustochytrids are considered natural producers of omega-3 fatty acids as they can synthesize up to 70% docosahexaenoic acids (DHA) of total lipids. However, commercial and sustainable production of microbial DHA is limited by elevated cost of carbon substrates for thraustochytrids cultivation. This problem can be addressed by utilizing low-cost renewable substrates. In the present study, growth, lipid accumulation and fatty acid profiles of the marine thraustochytrid Aurantiochytrium sp. T66 (ATCC-PRA-276) cultivated on volatile fatty acids (C1, formic acid; C2, acetic acid; C3, propionic acid; C4, butyric acid; C5, valeric acid and C6, caproic acid) and glucose as control were evaluated for the first time. This strain showed an inability to utilize C3, C5 and C6 as a substrate when provided at >2 g/L, while efficiently utilizing C2 and C4 up to 40 g/L. The highest cell dry weight (12.35 g/L) and total lipid concentration (6.59 g/L) were attained when this strain was cultivated on 40 g/L of butyric acid, followed by cultivation on glucose (11.87 g/L and 5.34 g/L, respectively) and acetic acid (8.70 g/L and 3.43 g/L, respectively). With 40 g/L butyric acid, the maximum docosahexaenoic acid content was 2.81 g/L, corresponding to 42.63% w/w of total lipids and a yield of 0.23 g/gcell dry weight (CDW). This marine oleaginous microorganism showed an elevated potential for polyunsaturated fatty acids production at higher acetic and butyric acid concentrations than previously reported. Moreover, fluorescence microscopy revealed that growth on butyric acid caused cell size to increase to 45 µm, one of the largest values reported for oleaginous microorganisms, as well as the presence of numerous tiny lipid droplets.

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Interconversions and production of volatile fatty acids in the sheep rumen

Biochemical Journal ◽

10.1042/bj0970053 ◽

1965 ◽

Vol 97 (1) ◽

pp. 53-58 ◽

Cited By ~ 80

Author(s):

EN Bergman ◽

RS Reid ◽

MG Murray ◽

JM Brockway ◽

FG Whitelaw

Keyword(s):

Fatty Acids ◽

Acetic Acid ◽

Steady State ◽

Energy Expenditure ◽

Propionic Acid ◽

Butyric Acid ◽

Volatile Fatty Acids ◽

Net Production ◽

Constant Rate ◽

Sheep Rumen

1. Sheep fed at a constant rate were infused intraruminally with [1-(14)C]-acetate, -propionate or -butyrate during 5hr. periods. 2. Volatile fatty acids were estimated in the rumen contents and steady-state conditions were obtained. 3. Of the butyric acid carbon 60% was in equilibrium with 20% of the acetic acid carbon, and 2-3g.atoms of carbon were interconverted/day. 4. Little interconversion took place between propionic acid, acetic acid or butyric acid. 5. The net production rates for acetic acid, propionic acid and butyric acid were 3.7, 1.0 and 0.7moles/day respectively. 6. The production of volatile fatty acids accounted for 80% of the animal's energy expenditure.

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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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