scholarly journals Measurement of Acetate in Aqueous Solutions and Plasma by Gas Phase Chromatography using a Porous Polymer Stationary Phase

1978 ◽  
Vol 15 (1-6) ◽  
pp. 228-232 ◽  
Author(s):  
M. F. Laker ◽  
M. A. Mansell
Keyword(s):  
Fatty Acids ◽  
Stationary Phase ◽  
Gas Phase ◽  
Retention Time ◽  
Healthy Subjects ◽  
Volatile Fatty Acids ◽  
Reference Range ◽  
Porous Polymer ◽  
Plasma Samples ◽  
Apparently Healthy

Summary A method of acetate determination by gas phase chromatography using a porous polymer stationary phase is reported that is suitable for use with aqueous and plasma samples. It is linear up to 100 mmol/l and has a coefficient of variation of less than 4 % for acetate values of greater than 1 mmol/l. The recovery of acetate from plasma is 92 % and sample retention time is 3 minutes. The reference range of plasma acetate in a group of 40 apparently healthy subjects was from less than 0·1 to 0·35 mmol/l. The frequently encountered problem of adsorption and ghosting of volatile fatty acids is overcome without the addition of formic acid vapour to the carrier gas.

scholarly journals Volatile Fatty Acids and Biomethane Recovery from Thickened Waste Activated Sludge: Hydrothermal Pretreatment’s Retention Time Impact

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1580
Author(s):  
Farokh laqa Kakar ◽  
Ahmed El Sayed ◽  
Neha Purohit ◽  
Elsayed Elbeshbishy
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Hydrothermal Pretreatment ◽  
Waste Activated Sludge ◽  
Optimum Conditions ◽  
Pretreatment Temperature ◽  
Biomethane Production

The main objective of this study was to evaluate the hydrothermal pretreatment’s retention time influence on the volatile fatty acids and biomethane production from thickened waste activated sludge under mesophilic conditions. Six different retention times of 10, 20, 30, 40, 50, and 60 min were investigated while the hydrothermal pretreatment temperature was kept at 170 °C. The results showed that the chemical oxygen demand (COD) solubilization increased by increasing the hydrothermal pretreatment retention time up to 30 min and stabilized afterwards. The highest COD solubilization of 48% was observed for the sample pretreated at 170 °C for 30 min. Similarly, the sample pretreated at 170 °C for 30 min demonstrated the highest volatile fatty acids yield of 14.5 g COD/Lsubstrate added and a methane yield of 225 mL CH4/g TCODadded compared to 4.3 g COD/Lsubstrate added and 163 mL CH4/g TCODadded for the raw sample, respectively. The outcome of this study revealed that the optimum conditions for solubilization are not necessarily associated with the best fermentation and/or digestion performance.

scholarly journals Effect of Hydrothermal Pretreatment on Volatile Fatty Acids Production from Source-Separated Organics

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 576 ◽  
Author(s):  
Farokh laqa Kakar ◽  
Ehssan Hosseini Koupaie ◽  
Hisham Hafez ◽  
Elsayed Elbeshbishy
Keyword(s):  
Fatty Acids ◽  
Chemical Oxygen Demand ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Hydrothermal Pretreatment ◽  
Soluble Substance ◽  
Pretreatment Temperature

The current study investigates the effect of hydrothermal pretreatment (HTP) on acidification of source-separated organics (SSO) in terms of volatile fatty acids (VFAs) production and solubilization. Temperature and retention time for HTP of SSO ranged from 150 to 240 °C and 5 to 30 min, respectively. The soluble substance after hydrothermal pretreatment initially increased, reaching its peak at 210 °C and then declined gradually. The highest overall chemical oxygen demand (COD) solubilization of 63% was observed at “210 °C-20 min” compared to 17% for raw SSO. The highest VFAs yield of 1536 mg VFAs/g VSS added was observed at “210 °C-20 min” compared to 768 mg VFAs/g VSS for raw SSO. Intensification of hydrothermal pretreatment temperature beyond 210 °C resulted in the mineralization of the organics and adversely affected the process.

scholarly journals The Effect of pH And Hydraulic Retention Time On Production Of Volatile Fatty Acids From Primary Sludge Anaerobic Fermentation

2021 ◽  
Author(s):  
Umme Sharmeen Hyder
Keyword(s):  
Fatty Acids ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Hydraulic Retention Time ◽  
Wastewater Treatment Plants ◽  
Anaerobic Fermentation ◽  
Nitrogen And Phosphorus ◽  
Primary Sludge ◽  
Effect Of Ph ◽  
Ph Range

Primary Sludge (PS) from wastewater treatment plants contains high biodegradable organic matter and therefore can be used to produce Volatile Fatty Acids (VFAs). The produced VFAs can be utilized in biological nitrogen and phosphorus removal processes as an external carbon source. The objective of this research was to investigate the effect of pH and hydraulic retention time (HRT) on the production of VFAs from PS through the anaerobic fermentation process. The experiments were conducted in both batch and semi-continuous flow regimes using bench scale fermenters under the mesophilic temperature. The Design of experiments included the HRT of 1 – 3 days and pH range of 4.5 - 11.0 for batch and 4.5 - 6.5 for semi-continuous modes. According to the obtained results, the VFAs production increased with an increase in HRT from 1 to 3 days. For the batch study, the pH range for maximum VFAs yield was pH 6.5 –10.0 achieved at HRT of 3 days. For the semi-continuous study, the maximum amount of VFAs production was observed at a pH of 6.5 and HRT of 3 days.

scholarly journals The Effect of pH And Hydraulic Retention Time On Production Of Volatile Fatty Acids From Primary Sludge Anaerobic Fermentation

2021 ◽  
Author(s):  
Umme Sharmeen Hyder
Keyword(s):  
Fatty Acids ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Hydraulic Retention Time ◽  
Wastewater Treatment Plants ◽  
Anaerobic Fermentation ◽  
Nitrogen And Phosphorus ◽  
Primary Sludge ◽  
Effect Of Ph ◽  
Ph Range

Primary Sludge (PS) from wastewater treatment plants contains high biodegradable organic matter and therefore can be used to produce Volatile Fatty Acids (VFAs). The produced VFAs can be utilized in biological nitrogen and phosphorus removal processes as an external carbon source. The objective of this research was to investigate the effect of pH and hydraulic retention time (HRT) on the production of VFAs from PS through the anaerobic fermentation process. The experiments were conducted in both batch and semi-continuous flow regimes using bench scale fermenters under the mesophilic temperature. The Design of experiments included the HRT of 1 – 3 days and pH range of 4.5 - 11.0 for batch and 4.5 - 6.5 for semi-continuous modes. According to the obtained results, the VFAs production increased with an increase in HRT from 1 to 3 days. For the batch study, the pH range for maximum VFAs yield was pH 6.5 –10.0 achieved at HRT of 3 days. For the semi-continuous study, the maximum amount of VFAs production was observed at a pH of 6.5 and HRT of 3 days.

Online headspace chromatographic method for measuring VFA in biogas reactor

2005 ◽  
Vol 52 (1-2) ◽  
pp. 473-478 ◽  
Author(s):  
K. Boe ◽  
D.J. Batstone ◽  
I. Angelidaki
Keyword(s):  
Fatty Acids ◽  
Organic Acid ◽  
Gas Phase ◽  
Volatile Fatty Acids ◽  
Chromatographic Method ◽  
Negative Impact ◽  
Automated System ◽  
Liquid Volume ◽  
Strong Impact ◽  
Short Period

A headspace chromatographic method has been applied to measure volatile fatty acids in anaerobic digesters using gas phase extraction at pH less than 2 and temperature higher than 65 °C. The concentration of volatile fatty acids in liquid and gas phase can be correlated in the form of Henry's coefficient. Analysis of different factors in the batch indicated that pH, temperature, and salt addition had a strong impact on apparent solubility, while liquid/gas volume ratio and organic acid concentration had little impact. Larger liquid volume had a positive impact on extraction efficiency, while increased gas headspace had a negative impact, indicating that the system was total mass-limited. The best conditions were at pH < 2.0, and temperatures above 75 °C. The advantage of an automated gas-extraction system for organic acid analysis, compared to an automated liquid system is that it contains no filter element, which is susceptible to fouling in manure samples or samples with high solid content. An automated system which included a valerate pulse to the parent reactor was implemented, and operated for a short period.

scholarly journals Effect of pH and hydraulic retention time on volatile fatty acids production from real waste in dark fermentation process

2021 ◽  
Author(s):  
Muhammed Ali Abdullah Khan
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Hydraulic Retention Time ◽  
Oxygen Demand ◽  
Biological Nutrient Removal ◽  
Waste Activated Sludge ◽  
Carbon Substrate ◽  
Primary Sludge

Waste-derived volatile fatty acids (VFAs) is an important carbon substrate for microorganisms engaged in the production of bioenergy, biodegradable plastics, and biological nutrient removal process. In this project, the generation and applications of waste-derived VFA were examined. Three solid wastes were used Primary sludge (PS), thickened waste activated sludge (TWAS) which were collected from Ashbridges Bay and source separated organics (SSO) that was collected from Disco Road facility. All the water quality analyses such as pH, TCOD, SCOD, TVFA, TSS, VSS, NH3 and, alkalinity were monitored. The results of this study showed that with increasing the Hydraulic retention time (HRT), the percentage of acidification increased. Furthermore, the results showed that alkaline pH was better than the acid pHs. Keywords: Total Volatile Fatty Acids, Soluble Chemical Oxygen Demand, Primary Sludge, Thickened Waste Activated Sludge, Source Separated Organics.

scholarly journals Modeling Of Dark Fermentation Process For Volatile Fatty Acids Production

2021 ◽  
Author(s):  
Raman Sharma
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Retention Time ◽  
Alternative Energy ◽  
Fossil Fuels ◽  
Fermentation Process ◽  
Volatile Fatty Acids ◽  
Solid Retention Time ◽  
Steady State Model ◽  
Complex Organic

This study examined the fermentation process for the production of volatile fatty acids from the organic waste. The depletion of fossil fuels motivated researchers to search for alternative energy and fuels instead of relying on the non-renewable way of energy and fuel production. Anaerobic digestion is a biochemical process in the absence of oxygen, where complex organic matter are degraded. The different stages of anaerobic digestion and important operating parameters such as pH, temperature and retention time. The most suitable feedstock and its effects on the treatment process are discussed. This study evaluates the modelling of VFAs production. The paper also demonstrates various model like ADM1, surface limiting model, and steady-state model. Furthermore, an experimental setup consisting of two semi-continuous reactors was employed for the sample analysis. The reactors were fed with raw and pre-treated source separated organics with solid retention time of 3 days. Keywords: Anaerobic digestion, Feedstocks, SSO, VFAs, ADM1

scholarly journals Modeling Of Dark Fermentation Process For Volatile Fatty Acids Production

2021 ◽  
Author(s):  
Raman Sharma
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Retention Time ◽  
Alternative Energy ◽  
Fossil Fuels ◽  
Fermentation Process ◽  
Volatile Fatty Acids ◽  
Solid Retention Time ◽  
Steady State Model ◽  
Complex Organic

This study examined the fermentation process for the production of volatile fatty acids from the organic waste. The depletion of fossil fuels motivated researchers to search for alternative energy and fuels instead of relying on the non-renewable way of energy and fuel production. Anaerobic digestion is a biochemical process in the absence of oxygen, where complex organic matter are degraded. The different stages of anaerobic digestion and important operating parameters such as pH, temperature and retention time. The most suitable feedstock and its effects on the treatment process are discussed. This study evaluates the modelling of VFAs production. The paper also demonstrates various model like ADM1, surface limiting model, and steady-state model. Furthermore, an experimental setup consisting of two semi-continuous reactors was employed for the sample analysis. The reactors were fed with raw and pre-treated source separated organics with solid retention time of 3 days. Keywords: Anaerobic digestion, Feedstocks, SSO, VFAs, ADM1

scholarly journals Effect of the solid retention time in the obtention of polyhydroxyalkanoates

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 864
Author(s):  
Rolando Calero ◽  
Manuel Martínez
Keyword(s):  
Fatty Acids ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Batch Reactor ◽  
Oxygen Demand ◽  
Solid Retention Time ◽  
Dry Cell Weight ◽  
Acidogenic Reactor ◽  
Mixed Microbial Cultures ◽  
Dry Cell

Background: The effect of solid retention time (SRT) over cheese whey substrates in a fermentation process drives changes in the composition of polyhydroxyalkanoates (PHAs) obtained. Volatile fatty acids produced in the first step of an anaerobic sequencing batch reactor were used as substrates to produce PHA using mixed microbial cultures under aerobic dynamic feeding conditions. Methods: Analytical methods were used for the standard analysis of parameters of interest including measuring the amount of ammonium and phosphate, chemical oxygen demand, among others. Results: The SRT increasing from 4 to 6 and 10 days produced changes in the distribution of volatile fatty acids produced. The polyhydroxybutyrate-hydroxyvalerate copolymers formed in the accumulation stage gave the following results: 58:42, 68:32 and 81:19 (%), referred to SRTs of 10, 6 and 4 days, respectively. The maximum PHA accumulation obtained at 10 days of SRT was 52% of the dry cell weight within 7 h, reaching a PHA productivity of 0.62 g L−1 h−1 and a storage yield of 0.37. Conclusion: The SRT variation impact on the distribution of volatile fatty acids in the acidogenic reactor and consequently on the PHA production and composition formed in the accumulation stage.

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