Abstract
The volatile fatty acid (VFA) production potential from animal blood and the factors affecting this process were investigated in this study. In order to simulate an industrial process different operation modes, batch, fed batch and semi-continuous, were also evaluated. Due to high ammonia concentration in fermentation broth, VFA concentration up to 100 g L−1 was achieved without addition of buffer and methanogen inhibitor. In general, acetic, n-butyric and iso-valeric acids were the most predominant species, although different operational conditions affected the VFA concentration, profile, production rate and yield. The microbial community analysis was conducted on the reactors with the best performance, revealing that 70–90% of the microbial population was from the Clostridiales order with a strong presence from the Sporanaerobacter genus. These results demonstrated the feasibility of a VFA platform bio-refinery using high-protein wastes as substrate via mixed-culture fermentation under non-sterilised conditions.
Highlights
The European Union produces more than 40 million tonnes of meat every year [1], with pig meat being the most important source (51%) followed by poultry (30%), bovine (17%) and sheep and goat meat (2%) [1]
The volatile fatty acid (VFA) concentrations reached up to 20 g L−1 when using lignocellulosic material such as paper wastes [6], and maize silage [16] as substrates. Waste biomass such as food waste (Resulting VFA concentration 20 g L−1) [17], mixture of waste activated sludge and henna plant biomass (11 g L−1) [18], glycerol (16 g L−1) [8] and cheese whey (20 g L−1) [16] have been used for VFA production, with concentrations considerably lower than what obtained in this study with slaughterhouse blood
The high VFA concentration achieved in this work can be attributed to the sufficient buffering capacity in the fermenters which is provided by the high concentration of Total ammonia nitrogen (TAN) in the system [4]
Summary
The European Union produces more than 40 million tonnes of meat every year [1], with pig meat being the most important source (51%) followed by poultry (30%), bovine (17%) and sheep and goat meat (2%) [1]. Meat production is associated with the generation of different types of solid (intestines, fat, bowels, etc.) and liquid (blood, manure, washing water, etc.) wastes [2]. Livestock blood from slaughterhouses is a proteinrich waste. As most protein-rich waste stream, its organic fraction is principally composed of proteins (94.4%), lipids (0.3%) and carbohydrates (5.3%) [3]. In order to transform blood into biogas via anaerobic digestion without suffering. Water and Environmental Engineering Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
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