scholarly journals A New Mathematical Model for the Accurate Determination of Volatile Fatty Acids Concentration in Anaerobic Digesters

2020 ◽  
Vol 06 (02) ◽  
pp. 67-84
Author(s):  
Gaston Nsavyimana ◽  
Salvator Kaboneka ◽  
Casimir Harerimana ◽  
Chema Keffala ◽  
Marc Elskens ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Accurate Determination ◽  
Anaerobic Digesters

scholarly journals A Simple and Accurate Approach for Determining the VFA Concentration in Anaerobic Digestion Liquors, Relying on Two Titration Points and an External Inorganic Carbon Analysis

2021 ◽  
Vol 5 (2) ◽  
pp. 15
Author(s):  
Paz Nativ ◽  
Yonatan Gräber ◽  
Yaron Aviezer ◽  
Ori Lahav
Keyword(s):  
Partial Pressure ◽  
Volatile Fatty Acids ◽  
Inorganic Carbon ◽  
Strong Acid ◽  
Direct Analysis ◽  
Anaerobic Digesters ◽  
Acid Titration ◽  
Partial Pressure Of Co2 ◽  
Ph Range

A new analytic approach is presented for determining the total volatile fatty acids (VFAT) concentration in anaerobic digesters. The approach relies on external determination of the inorganic carbon concentration (CT) in the analyzed solution, along with two strong-acid titration points. The CT concentration can be determined by either a direct analysis (e.g., by using a TOC device) or by estimating it from the recorded partial pressure of CO2(g) in the biogas (often a routine analysis in anaerobic digesters). The titration is carried out to pH 5.25 and then to pH 4.25. The two titration results are plugged into an alkalinity-mass-based equation and then the two terms are subtracted from each other to yield an equation in which VFAT is the sole unknown (since CT is known and the effect of the total orthophosphate and ammonia concentrations is shown to be small at this pH range). The development of the algorithm and its verification on four anaerobic reactor liquors is presented, on both the raw water and on acetic acid-spiked samples. The results show the method to be both accurate (up to 2.5% of the expected value for VFAT/Alkalinity >0.2) and repetitive when the total orthophosphate and ammonia concentrations are known, and fairly accurate (±5% for VFAT >5 mM) when these are completely neglected. PHREEQC-assisted computation of CT from the knowledge of the partial pressure of CO2(g) in the biogas (and pH, EC and temperature in the liquor) resulted in a very good estimation of the CT value (±3%), indicating that this technique is adequate for the purpose of determining VFAT for alarming operators in case of process deterioration and imminent failure.

Determination of soluble carbohydrates, lactic acid and volatile fatty acids in soils and biological media

1929 ◽  
Vol 19 (4) ◽  
pp. 649-655 ◽  
Author(s):  
V. Subrahmanyan
Keyword(s):  
Fatty Acids ◽  
Lactic Acid ◽  
Volatile Fatty Acids ◽  
Soluble Carbohydrates ◽  
Biological Media ◽  
Factors Affecting

Methods for extraction, concentration and determination of minute quantities of soluble carbohydrates, lactic acid and volatile fatty acids have been described. Different factors affecting the accuracy of the determinations have been studied and corrections, where necessary, have been suggested.

scholarly journals Determination of Volatile Fatty Acids in Bovine Blood by Isotope Dilution

1959 ◽  
Vol 42 (2) ◽  
pp. 358-362
Author(s):  
J.B. Holter ◽  
S. Lakshmanan ◽  
J.C. Shaw
Keyword(s):  
Fatty Acids ◽  
Isotope Dilution ◽  
Volatile Fatty Acids ◽  
Bovine Blood

A modified two-point titration method for the determination of volatile fatty acids in anaerobic systems

Chemosphere ◽  
2018 ◽  
Vol 204 ◽  
pp. 251-256 ◽  
Author(s):  
Zhe-Xuan Mu ◽  
Chuan-Shu He ◽  
Jian-Kai Jiang ◽  
Jie Zhang ◽  
Hou-Yun Yang ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Titration Method

Application of Methanobrevibacter acididurans in anaerobic digestion

2004 ◽  
Vol 50 (6) ◽  
pp. 109-114 ◽  
Author(s):  
D.V. Savant ◽  
D.R. Ranade
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Methane Production ◽  
Volatile Fatty Acids ◽  
Low Ph ◽  
Anaerobic Digesters ◽  
Hydrogenotrophic Methanogen ◽  
Distillery Wastewater ◽  
Acid Tolerant ◽  
Acidic Conditions

To operate anaerobic digesters successfully under acidic conditions, hydrogen utilizing methanogens which can grow efficiently at low pH and tolerate high volatile fatty acids (VFA) are desirable. An acid tolerant hydrogenotrophic methanogen viz. Methanobrevibacter acididurans isolated from slurry of an anaerobic digester running on alcohol distillery wastewater has been described earlier by this lab. This organism could grow optimally at pH 6.0. In the experiments reported herein, M. acididurans showed better methanogenesis under acidic conditions with high VFA, particularly acetate, than Methanobacterium bryantii, a common hydrogenotrophic inhabitant of anaerobic digesters. Addition of M. acididurans culture to digesting slurry of acidogenic as well as methanogenic digesters running on distillery wastewater showed increase in methane production and decrease in accumulation of volatile fatty acids. The results proved the feasibility of application of M. acididurans in anaerobic digesters.

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

2013 ◽  
Vol 69 (3) ◽  
pp. 495-503 ◽  
Author(s):  
M.-P. Zacharof ◽  
R. W. Lovitt
Keyword(s):  
Fatty Acids ◽  
Acetic Acid ◽  
Butyric Acid ◽  
Volatile Fatty Acids ◽  
Agricultural Waste ◽  
Permeate Flux ◽  
Anaerobic Digesters ◽  
Waste Effluents

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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