Complex Effluent Streams as a Potential Source of Volatile Fatty Acids (original) (raw)
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The 4th International Conference on Engineering for Waste and Biomass Valorisation September 10-13, 2012 – Porto, Portugal (WasteEng12)PROCEEDINGS (Vol 3)Edited by A. Nzihou and F. Castro pp:861-865 ISBN:979-10-91526-00-5, 2012
The removal of Volatile Fatty Acids (VFA) , from wastewater deriving from numerous sources such as chemical plants has been an area of research interest for more than a century. With the global petroleum resources facing scarcity and the constantly rising awareness of the environmental impact the carbon based economy has created , research has been focused in developing alternative methods of their production, such as biofermentation. In biofermentation, the hydrolysis of target solid wastes followed by the microbial conversion of them to biodegradable organic content results in the production of intermediate organic acids, specifically VFA. VFA are detected at high concentrations in the effluent streams and mixed liquors of anaerobic membrane reactor systems, because of sudden variations in hydraulic and organic loading rates. Several studies have shown possible environmental and commercial benefits using filtration as a source separation process in comparison to integral wastewater treatment. These benefits include the relief of municipal treatment plants, the use of favourable nutrients and the composition of urine free wastewater for biotreatment. and insufficient capacity of microfiltration and ultrafiltration systems for their rejection, mainly due to their low molecular weight. Anaerobic effluents need to be treated with a more advanced treatment process such as nanofiltration and reverse osmosis.
Proceedings,Venice 2012, Fourth International Symposium on Energy from Biomass and Waste,ISBN:978-88-6265-006-9, 2012
"Volatile fatty acids (VFA) including acetic, butyric, formic and propionic are extensively utilized in contemporary industry. Their commercial value is of high significance while their often derive from petroleum which is non-abundance source. Other methods for the production and recovery from these substances have been proposed and investigated. Waste effluent streams are potential candidates for VFA recovery, especially if for their processing filtration technology will be used. Membrane filtration is an effective and efficient choice as it is a low cost, low energy, easy integrated method tested for the separation and concentration. "
Recovery of volatile fatty acids (VFA) from complex waste effluents using membranes
doi:10.2166/wst.2013.717, 2013
Waste effluents from anaerobic digesters of agricultural waste were treated with a range of membranes including microfiltration and nanofiltration to concentrate volatile fatty acids. 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 nanofiltration membranes (NF270, (Dow Chemicals, USA), HL, DL, DK, (Osmonics , USA), LF10 (Nitto Denko, Japan) achieving retention ratios, up to 75% giving retentates up to 53.94 mM acetate and 28.38 mM 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 highest productivity, retention and flux was achieved at pH 7 at higher pH there was a significant reduction in flux.
Fermentation, 2021
The hydrocarbon-based economy is moving at a large pace to a decarbonized sustainable bioeconomy based on biorefining all types of secondary carbohydrate-based raw materials. In this work, 50 g L−1 in COD of a mixture of food waste, brine and wastewater derived from a biodiesel production facility were used to produce organic acids, important building-blocks for a biobased industry. High salinity (12–18 g L−1), different reactors configuration operated in batch mode, and different initial pH were tested. In experiment I, a batch stirred reactor (BSR) at atmospheric pressure and a granular sludge bed column (GSBC) were tested with an initial pH of 5. In the end of the experiment, the acidification yield (ηa) was similar in both reactors (22–24%, w/w); nevertheless, lactic acid was in lower concentrations in BSR (6.3 g L−1 in COD), when compared to GSBC (8.0 g L−1 in COD), and valeric was the dominant acid, reaching 17.3% (w/w) in the BSR. In experiment II, the BSR and a pressurized b...
Volatile Fatty Acid Production from Organic Waste with the Emphasis on Membrane-Based Recovery
Fermentation
In recent years, interest in the biorefinery concept has emerged in the utilization of volatile fatty acids (VFAs) produced by acidogenic fermentation as precursors for various biotechnological processes. This has attracted substantial attention to VFA production from low-cost substrates such as organic waste and membrane based VFA recovery techniques to achieve cost-effective and environmentally friendly processes. However, there are few reviews which emphasize the acidogenic fermentation of organic waste into VFAs, and VFA recovery. Therefore, this article comprehensively summarizes VFA production, the factors affecting VFA production, and VFA recovery strategies using membrane-based techniques. Additionally, the outlook for future research on VFA production is discussed.
Anaerobic fermentation of organic solid wastes: volatile fatty acid production and separation
Water Science and Technology, 2014
Anaerobic fermentation of organic municipal solid waste was investigated using a leach-bed reactor (LBR) to assess the volatile fatty acid (VFA) production efficiency. The leachate recycle rate in the LBR affected the VFA composition of the leachate. A six-fold increase in the recycle rate resulted in an increase of the acetic acid fraction of leachate from 24.7 to 43.0%. The separation of VFAs via leachate replacement resulted in higher total VFA production. VFA separation from synthetic VFA mix and leachate of a fermented organic waste was assessed via a counter-current flow polytetrafluoroethylene (PTFE) membrane contactor. Acetic and propionic acid permeation fluxes of 13.12 and 14.21 g/m2.h were obtained at low feed pH values when a synthetic VFA mix was used as a feed solution. The highest selectivity was obtained for caproic acid compared to that of other VFAs when synthetic VFA mix or leachate was used as a feed solution. High pH values and the presence of suspended solids i...