Whiskey distillery waste streams consisting of pot ale (liquid residue) and spent grain (solid residue) are high strength organic wastes and suitable feedstock for anaerobic digestion (AD) from both economic and environmental stand points. Anaerobic digestion of pot ale and pot ale/spent grain mixtures (with mixing ratios of 1:1, 1:3, and 1:5 by wet weight) was performed after implementation of a novel hybrid pre-treatment (combined chemical and mechanical) in order to modify lignocellulosic structure and ultimately enhance digestion yield. Lignin, hemicellulose, and cellulose fractions were determined before and after chemical pre-treatment. Effects of different inoculum rates (10-30-50% on wet basis) and beating times (0-7.5-15 min) on anaerobic digestion of pot ale alone and of pot ale/spent grain mixtures were investigated in lab scale batch mode with a major focus of optimising biogas yield by using response surface methodology (RSM) in Design Expert Software. The highest biogas yields of 629 ± 8.5 mL/g vs. (51.3% CH 4 ) and 360 ± 10 mL/g vs. (55.0 ± 0.4) with anaerobic digestion of pot ale alone and spent grain mix after 1M NaOH and 7.5 min beating pre-treatments with 50% inoculum ratio respectively. The optimum digestion conditions to maximise the biogas quality and quantity were predicted as 10 and 13 min beating times and 32 and 38 • C digestion temperatures for anaerobic digestion of pot ale alone and spent grain mix respectively.Processes 2020, 8, 492 2 of 27 of alternative energy sources has arisen [5]. Among the renewable energy sources, biogas, which is methane rich gas produced by anaerobic digestion (AD) of organic waste, is considered to be among the most environmentally friendly fuel sources [6] owing to its non-toxic characteristics and potential for simplicity of use as an alternative over traditional fossil fuels, as well as its potential reduction in wastes sent to landfill [7].Typical waste disposal levels of whiskey distilleries and breweries and the potential environmental concerns associated with those waste streams was outlined by [8]. Due to the high organic content, large disposal volume, and the acidic nature, pot ale is the major concern of the waste management of whiskey distilleries. As such, AD with advantages over other waste management methods like low energy requirement, odour limitation, less by-product generation, and higher ability to cope with recalcitrant nature of whiskey distillery/brewery waste streams is a suitable alternative waste treatment method [9][10][11][12]. There are four main stages in the AD process-namely hydrolysis, acidogenesis, acetogenesis, and methanogenesis-and the reactions in each stage are carried out by different bacteria. The thermodynamics of each AD stage and potential bacterial competitions have been reported in detail by [13,14]. In order to have a balanced AD, identical reaction rates are desired, however, the hydrolysis step is considered to be the rate limiting step for the digestion of lignocellulosic matter due to the impact of high lig...
Standardization of annatto in aqueous solution has been shown to be unsound, and it has been recommended that standardization be carried out on the basis of the depth of colour produced in cheese itself.A paper colour standard resembling the German butter standard has been suggested for cheese, the same standard being suitable for the evaluation of annatto solutions for cheese-making.
<p>Butanol and Isopropanol are naturally produced by the bacteria C. beijerinckii. Those products are used in large field of applications such as fuel and bulk chemicals. Since butanol is toxic at small concentration for cells, bacterial growth and metabolism are inhibited during classical batch fermentation (1). These phenomena lead to the production of low solvent concentration (around 7 g.L<sup>-1</sup>) and a low volumetric productivity (0,13 g.L<sup>-1</sup>.h<sup>-1</sup>) (2). Continuous fermentation can be performed in order to avoid product inhibition by&#160; a continuous removal of fermentation broth. However, the solvent productive biomass is easily washout at high dilution rate because of the low maximum growth rate of the strain in this metabolism phase&#160; (0,05 h<sup>-1</sup>) (3). To overcome this issue, cell immobilization of&#160; C. beijerinckii by biofilm formation on solid support is the best solution. As a result, the biomass residence time can be uncorrelated from the hydraulic residence time leading to a higher viable biomass concentration in the bioreactor and consequently a higher volumetric productivity (up to 5 g.L<sup>-1</sup>.h-1 ) (4). Our study aimed&#160; at evaluating biofilm viability which is an important parameter that is linked to process productivity and has been little studied in the case of the IBE fermentation (5).</p> <p>In this study we developed two techniques to monitor biofilm viability during immobilized cell fermentation: Flow cytometry (FC) and PMA qPCR. After FC analysis, a high background noise due to the biofilm extra polymeric substance is obtained. Consequently, an enzymatic&#160; sequential enzymatic biofilm deconstruction using Dnase I and Proteinase K was developed . This pre-treatment successfully lowered the background noise of this analysis. The suspensions obtained were stained with carboxyfluoresceine diacetate (cFDA) and propidium iodide (PI) which are indicators of cellular activity and alteration of membrane integrity, respectively,&#160; and analyzed by flow cytometry. The percentage of viable cells obtained after pre-treatment compared to the control sample is increased from 2.6 &#177; 0.9 % to 22.8 &#177; 8.6% because of the background noise decrease. PMA-qPCR confirmed the results obtained by flow cytometry without using enzymatic pre-treatment. Although FC is less accurate than PMA-qPCR, this technique is less time-consuming, cheaper and reliable to study biofilm viability.</p> <p><strong>References</strong></p> <ol> <li>Jones et al (1986) Acetone-Butanol Fermentation Revisited, Microbiological Reviews 50, 484&#8211;524.</li> <li>Ferreira dos Santos Vieira, C., Maugeri Filho, F., Maciel Filho, R., and Pinto Mariano, A. (2019) Isopropanol-butanol-ethanol (IBE) production in repeated-batch cultivation of Clostridium beijerinckii DSM 6423 immobilized on sugarcane bagasse, Fuel, 116708.</li> <li>Ahmed, I., Ross, R. A., Mathur, V. K., and Chesbro, W. R. (1988) Growth rate dependence of solventogenesis and solvents produced by Clostridium beijerinckii, Appl Microbiol Biotechnol 28, 182&#8211;187.</li> <li>Survase, S. A., van Heiningen, A., and Granstr&#246;m, T. (2013) Wood pulp as an immobilization matrix for the continuous production of isopropanol and butanol, J. Ind. Microbiol. Biotechnol. 40, 209&#8211;215.</li> <li>Qureshi, N., Lai, L. L., and Blaschek, H. P. (2004) Scale-Up of a High Productivity Continuous Biofilm Reactor to Produce Butanol by Adsorbed Cells of Clostridium Beijerinckii, Featuring Tissue Engineering 82, 164&#8211;173.</li> </ol>
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