An efficient downstream process without prior desalination was developed for recovering 1,3‐propanediol (1,3‐PDO) with high purity and yield from broth of a highly productive fed‐batch fermentation of raw glycerol by Clostridium pasteurianum. After removal of biomass and proteins by ultrafiltration, and concentration by water evaporation, 1,3‐PDO was directly recovered from the broth by vacuum distillation with continuous addition and regeneration of glycerol as a supporting agent. Inorganic salts in the fermentation broth were crystallized but well suspended by a continuous flow of glycerol during the distillation process, which prevented salt precipitation and decline of heat transfer. On the other hand, ammonium salt of organic acids were liberated as ammonia gas and free organic acids under vacuum heating. The latter ones formed four types of 1,3‐PDO esters of acetic acid and butyric acid, which resulted in yield losses and low purity of 1,3‐PDO (< 80%). In order to improve the efficiency of final 1,3‐PDO rectification, we examined alkaline hydrolysis to eliminate the ester impurities. By the use of 20% (w/w) water and 2% (w/w) sodium hydroxide, > 99% reduction of 1,3‐PDO esters was achieved. This step conveniently provided free 1,3‐PDO and the sodium salt of organic acids from the corresponding esters, which increased the 1,3‐PDO yield by 7% and prevented a renewed formation of esters. After a single stage distillation from the hydrolyzed broth and a followed active carbon treatment, 1,3‐PDO with a purity of 99.63% and an overall recovery yield of 76% was obtained. No wastewater with high‐salt content was produced during the whole downstream process. The results demonstrated that the monitoring and complete elimination of 1,3‐PDO esters are crucial for the efficient separation of highly pure 1,3‐PDO with acceptable yield from fermentation broth of raw glycerol.
Bioconversion of natural microorganisms generally results in a mixture of various compounds. Downstream processing (DSP) which only targets a single product often lacks economic competitiveness due to incomplete use of raw material and high cost of waste treatment for by-products. Here, we show with the efficient microbial conversion of crude glycerol by an artificially evolved strain and how a catalytic conversion strategy can improve the total products yield and process economy of the DSP. Specifically, Clostridium pasteurianum was first adapted to increased concentration of crude glycerol in a novel automatic laboratory evolution system. At m 3 scale bioreactor the strain achieved a simultaneous production of 1,3-propanediol (PDO), acetic and butyric acids at 81.21, 18.72, and 11.09 g/L within only 19 h, respectively, representing the most efficient fermentation of crude glycerol to targeted products. A heterogeneous catalytic step was developed and integrated into the DSP process to obtain high-value methyl esters from acetic and butyric acids at high yields. The coproduction of the esters also greatly simplified the recovery of PDO. For example, a cosmetic grade PDO (96% PDO) was easily obtained by a simple single-stage distillation process (with an overall yield more than 77%). This integrated approach provides an industrially attractive route for the simultaneous production of three appealing products from the crude glycerol fermentation broth, which greatly improve the process economy and ecology.
Aluminium ceramic (Al-Al2O3) is used comprehensively all over the world. In this paper, input parameters on Al-Al2O3 workpiece are applied to investigate the MRR and surface roughness by the process of wire electrical machining (WEDM).Four varying input parameters (Ton, Toff, Wf and Cs%) were tabulated for nine samples using L9 orthogonal array design technique whereas keeping wire tension as constant. Tool wear is calculated as the change in initial thickness and final thickness after cutting operation using screw gauge. The surface roughness is found using surface roughness tester.Minitab is used to plot the graph between input parameters against various output parameters. To find the impact of process parameters, ANOVA (Analysis of Variance) is used .
Bioconversion process with a single target product often lacks economic
competitiveness owing to incomplete use of raw material and high costs
of downstream processing (DSP). Here, we show with the microbial
conversion of crude glycerol that an integrated strain engineering and
catalytic conversion of the so-called byproducts can greatly improve DSP
and the process economy. Specifically, Clostridium pasteurianum was
first adapted to increased concentration of crude glycerol in a novel
automatic laboratory evolution system. At m3 scale bioreactor the strain
achieved a simultaneous production of 1,3-propanediol (PDO), acetic and
butyric acids at 81.21, 18.72 and 11.09 g/L within only 19 h,
respectively, representing the most efficient fermentation of crude
glycerol to targeted products. A heterogeneous catalytic step was
developed and integrated into the DSP process to obtain high-value
methyl esters from acetic and butyric acids at high yields. The
co-production of the esters also greatly simplified the recovery of PDO.
For example, a cosmetic grade PDO (96% PDO) was easily obtained by a
simple single-stage distillation process (with an overall yield more
than 77%). This integrated approach provides an industrially attractive
route for a complete use of the raw material with the simultaneous
production of three appealing products which greatly improve the process
economy and ecology.
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