Search results for "Volatile fatty acids"

Amaranthus grain as a new ingredient in diets for dairy cows: productive, qualitative, and in vitro fermentation traits

2022

Background: In recent decades, grain amaranths have attracted attention due to their valuable combination of nutritional traits, with higher protein and oil content than conventional cereals. Before they can be proposed as an unconventional ingredient in animal feed, many aspects still need to be investigated from field production to nutritive value. The present research aimed to study the agronomic traits, proximate composition, and digestibility/degradability, fatty acid profile, antioxidant activity, and total phenolic content of two grain amaranth species, Amaranthus cruentus and Amaranthus hypochondriacus (for a total of six accessions), grown in a Mediterranean environment. Results: B…

Influence of volatile solids and pH for the production of volatile fatty acids: batch fermentation tests using sewage sludge

2021

The aim of this work was to study the effect of volatile suspended solid (VSS) and pH on volatile fatty acids (VFA) production from waste activated sludge (WAS) fermentation by means of batch tests. The final goal was to gain insights to enhance VFA stream quality, with the novelty of using WAS with high sludge retention time. Results revealed that the optimum conditions to maximize VFAs and minimize nutrients and non-VFA sCOD are a VSS concentration of 5.9 g/L and initial pH adjustment to pH 10. The WAS bacterial community structures were analysed according to Next Generation Sequencing (NGS) of 16S rDNA amplicons. The results revealed changes of bacterial phyla abundance in comparison wit…

Volatile fatty acids (VFAs) and methane from food waste and cow slurry: Comparison of biogas and VFA fermentation processes

2018

Determination of volatile fatty acids in the hot springs of Vulcano, Aeolian Islands, Italy

1998

Abstract Samples of relatively acid hydrothermal fluids were collected in the spring of 1996 from seeps, springs, and wells on the Island of Vulcano in the southern Tyrrhenian Sea and analyzed for volatile fatty acids 1 using liquid chromatography. Concentrations of VFAs in the seeps were in the range 65–140 ppb formic, 133–184 ppb acetic, and

Modelació de sedimentadors en plantes de tractament d’aigües residuals. Aplicació al procés de fermentació – elutriació de fangs primaris

2005

La depuració de les aigües residuals requereix la consumació de molts processos de transformació de forma simultània i/o consecutiva, que fan molt difícil el seu estudi. A més, la complexitat dels processos de depuració va en augment no sols per l'aparició de requisits d’abocament cada vegada més exigents, sinó també per les noves tendències cap al desenvolupament sostenible aplicades a aquest procés i centrades fonamentalment en l’estalvi energètic i la recuperació de nutrients de les aigües residuals per millorar el seu cicle de vida. Per aquest motiu, es fa necessari l'ús d'eines de simulació que tinguen en compte tots aquests processos mitjançant un model matemàtic adequat i ajuden a de…

Identification and sensory evaluation of the character-impact compounds of goat cheese flavour

1996

1 SUMMARY The volatile compounds of various goat cheeses have been isolated in order to identify the character-impact odorants by a combination of instrumental analyses and sensory studies. Different extraction procedures have been studied in order to obtain a volatile fraction representative of the cheeses. The most representative extract, as determined by sensory evaluation, has been submitted to GC-MS and to GC-olfactometry, using the aroma extract dilution analysis (AEDA) method. The volatile fatty acids have been found to be the most important compounds for the characteristic goat flavour. Among them, branched-chain fatty acids ( e.g. , 4-methyloctanoic and 4-ethyloctanoic) have been f…

The metabolic versatility of PAOs as an opportunity to obtain a highly P-enriched stream for further P-recovery

2015

The effects of two sequencing batch reactor operation strategies for phosphorus stream enrichment over the biological phosphorus removal performance have been studied. The objective of both strategies is of performing an extraction cycle in order to obtain a new stream highly enriched with phosphorus. In the 1st strategy the amount of influent volatile fatty acids (VFAs) is the same in each cycle; while in the 2nd strategy the influent VFAs concentration is increased during phosphorus extraction experiments. Despite the strong decrease of the stored poly-P inside the cells in both strategies after the recovery cycles, the ability of the systems to remove phosphorus was not affected. The P-r…

Kinetics and characteristics of 70 °C, VFA-grown, UASB granular sludge

1999

We studied in batch reactors the kinetics and characterization of 70 °C, volatile fatty acids (VFAs)-grown, upflow anaerobic sludge blanket granular sludge with 55 and 35 °C sludge as reference. The half-saturation constant (Ks), the inhibition constant (Ki), the maximum specific methane production rate (μCH4max), and the inhibition response coefficient (n) of the 70 °C sludge were 6.15 mM, 48.2 mM, 0.132 h−1, and 2.48, respectively, while no inhibition occurred at 55 and 35 °C, where the Ks was 3.67 and 3.82 mM, respectively. At 70 °C, the highest initial specific methanogenic activity (ISMA, 0.311 gCH4-COD per gram volatile solids per day) on VFAs was about 12–15% lower than that on aceta…

Sewage sludge acidogenic fermentation for organic resource recovery towards carbon neutrality: an experimental survey testing the headspace influence

2022

Volatile fatty acids (VFAs) produced by acidogenic digestion of sewage sludge are very interesting bio-products which can contribute to carbon neutrality of wastewater treatment plants. Studies on the production of VFAs from sewage sludge from fermenters with membrane are limited. In view of above, VFAs from a fermenter pilot plant equipped with a membrane bioreactor and fed with real sewage sludge has been monitored. The effect of headspace volume (HdV) on VFA production was studied for the first time to elucidate the optimal operation conditions. Specifically, three fermenter HdV values (namely, 20, 40 and 60% of the total volume) have been investigated. Results revealed that the HdV of 2…

Water Resource Recovery Facilities (WRRFs): The Case Study of Palermo University (Italy)

2021

The wastewater sector paradigm is shifting from wastewater treatment to resource recovery. In addition, concerns regarding sustainability during the operation have increased. In this sense, there is a need to break barriers (i.e., social, economic, technological, legal, etc.) for moving forward towards water resource recovery facilities and demonstration case studies can be very effective and insightful. This paper presents a new water resource recovery case study which is part of the Horizon 2020 EU Project “Achieving wider uptake of water-smart solutions—Wider Uptake”. The final aim is to demonstrate the importance of a resource recovery system based on the circular economy concept. The r…