Volatile fatty acids , hydrogen

The concentrations of several specific odorants found in piggery slurry,in particular volatile fatty acids, hydrogen sulphide, ammonia and p-cresol, have been correlated with odour intensity (13, 14, 15 16). 

Fig. 5.15 Inhibitor experiment for the demonstration of substrates used by sulfate reducing bacteria in a coastal marine sediment. The concentrations of volatile fatty acids, hydrogen and methane are followed during a time-course experiment over 8 hours. At 3.5 hours (arrow) molybdate was added and the substrates accumulate at a rate corresponding to their rate of consumption before inhibition. The formation of methane shows the release of competition for the common substrates for methanogenesis and sulfate reduction (H and acetate). Data from Sorensen et al. (1981).

Figure 4. Developments of cumulative hydrogen yield, pH value, volatile fatty acids (VFAs) and alcohols in the batch reactor during the conversion of the substrate to biohydrogen under the pretreated condition of microwave heating...

Sprensen J., Christensen D., and Jprgensen B. B. (1981) Volatile fatty acids and hydrogen as substrates for sulfate-reducing bacteria. Appl. Environ. Microbiol. 42, 5—11. 

Sasaki, K., Takeno, K., and Emoto, Y. (1996). Utilization of organic acids and volatile fatty acids and hydrogen production by photosynthetic bacteria. J. Soc. Water. Environ. 19, 63-70, (in Japanese). 

Photosynthetic bacteria can rapidly assimilate volatile fatty acids and grow. Because it assimilates organic compounds, hydrogen production from various fatty acids has been investigated. As for volatile fatty acids, lactate obtained after lactate fermentation of carbohydrates and acetate contained in processed solution after methane fermentation can be used as a substrate. 

Kong, I. C., Hubbard, J. S., and Jones, W. J., Metal-induced inhibition of anaerobic metabolism of volatile fatty acids and hydrogen, Appl. Microbiol. Biotechnol., 42, 396-402, 1994. 

Westerman, P., The effect of incubation temperature on steady-state concentrations of hydrogen and volatile fatty acids during anaerobic degradation in slurries from wetland sediments, FEMS Microbiol. EcoL, 13, 295-302, 1994. 

Acetogenesis Clostridium, Syntrophomonas wolfei transform higher fatty acids or alcohols to hydrogen and acetate Syntrophomonas wolfei, Syntrophomonas wolinii convert volatile fatty acids and alcohols to acetate and hydrogen... 

Hydrolyzing and fermenting microorganisms are responsible for the initial attack on polymers and monomers and produce mainly acetate and hydrogen and some amounts of volatile fatty acids (VFA) such as propionate and butyrate. Hydrolytic microorganisms lead to hydrolytic enzymes, e.g., cellulose, cellobiase, xylanase, amylase, hpase, and protease. 

Schmidt described the products of fermentation of carbohydrate as consisting of the gases carbon dioxide, hydrogen and methane and lower volatile fatty acids which were for the most part absorbed by the intestinal wall. The fermentation products that were not absorbed were excreted, either mixed with the feces or as flatus. Putrefaction of protein produced... 

Argun H, Kargi F, Kapdan IK (2008a) Light fermentation of dark fermentation effluent for bio-hydrogen production by different Rhodobacter species at different initial volatile fatty acid (VFA) concentrations. Int J Hydrog Energy... 

Steinbusch KJJ, Mamelers HVM, Buisman CJN. 2008. Alcohol production through volatile fatty acids reduction with hydrogen as electron donor by mixed cultures. Water Res. 42 4059-4066. 

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