B. Sen; M. Torrijos; P. Sousbie; J. P. Steyer
Abstract
This study investigated the effect, on reactor performance and biomass retention inside the bed, of the material used to make the supports of anaerobic fixed-bed reactors. Three inert supports of similar shape but made of three different materials polyvinyl chloride, polypropylene, high-density polyethylene ...
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This study investigated the effect, on reactor performance and biomass retention inside the bed, of the material used to make the supports of anaerobic fixed-bed reactors. Three inert supports of similar shape but made of three different materials polyvinyl chloride, polypropylene, high-density polyethylene were manufactured and used. All three supports had the same specific surface area but different relative densities. Three identical 10 L lab-scale upflow anaerobic fixed-bed reactors were filled (80% of the working volume) each respectively with polyvinyl chloride, polypropylene and polyethylene support, and fed with vinasse (44 g total COD/L) for 140 days at 35 °C. The organic loading rates were increased from 0.5 g/L.d to the maximum acceptable by each reactor. Fairly similar maximum organic loading rates were reached for each type of support, with values above 20 g of COD/L.d and more than 80 % soluble chemical oxygen demand removal efficiency. A very large amount of biomass was entrapped and attached in all the supports and represented more than 95% of the total biomass inside the reactors. In terms of performance and biomass accumulation, this study demonstrated quite similar behavior for anaerobic fixed-bed reactors with supports made of different materials, which suggests that the nature of the material used to make the supports has no major influence. The chemical nature of the support material clearly has negligible effect and thus the size, shape, and porosity of the support must be more influential.
B. Sen; A.P. Dabir; V.B. Lanjekar; D.R. Ranade
Abstract
Glycerol is a promising feedstock for microbial cultivation and production of 1,3 propanediol (1,3 PDO). Here we report a newly isolated bacterial strain BA11 from soil, capable of fermenting glycerol to 1,3 PDO, and has been identified to be a strain of Klebsiella pneumoniae. Strain BA11 was fast growing ...
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Glycerol is a promising feedstock for microbial cultivation and production of 1,3 propanediol (1,3 PDO). Here we report a newly isolated bacterial strain BA11 from soil, capable of fermenting glycerol to 1,3 PDO, and has been identified to be a strain of Klebsiella pneumoniae. Strain BA11 was fast growing showing peak 1,3 PDO production in 6 h of cultivation with productivity of 1.2 g/L-h without the addition of Vitamin B12. Based on the optimum glycerol utilization (75%) and 1,3 PDO production (8.3 g/L) and yield (0.56 mol/mol glycerol utilized), the most appropriate glycerol concentration for cultivation was 20 g/L. The strain BA11 could tolerate the pH range of 6 to 8.5 as no inhibitory effects were seen on growth as well as 1,3 PDO production. Strain BA11 was most active and could produce high 1,3 PDO in the incubation temperature range of 25 to 40 oC. The production of 1,3 PDO was maximum (9.3 g/L) under aerobic condition with 95.8% glycerol utilization. Addition of glucose to the glycerol fermentation led to increased cell mass but no improvement in the 1,3 PDO production.