Improved stability of the continuous production of acetone-butanol by Clostridium acetobutylicum in a two-stage process

1988 ◽  
Vol 10 (6) ◽  
pp. 389-392 ◽  
Author(s):  
C. Godin ◽  
J. M. Engasser
Keyword(s):  
Clostridium Acetobutylicum ◽  
Continuous Production ◽  
Two Stage ◽  
Improved Stability ◽  
Stage Process

Continuous hydrogen and methane production in a two-stage cheese whey fermentation system

2011 ◽  
Vol 64 (2) ◽  
pp. 367-374 ◽  
Author(s):  
C. B. Cota-Navarro ◽  
J. Carrillo-Reyes ◽  
G. Davila-Vazquez ◽  
F. Alatriste-Mondragón ◽  
E. Razo-Flores
Keyword(s):  
Methane Production ◽  
Cheese Whey ◽  
Continuous Production ◽  
Uasb Reactor ◽  
Organic Loading Rate ◽  
Stable Operation ◽  
Operational Parameters ◽  
Two Stage ◽  
Production Of Hydrogen ◽  
Stage Process

The feasibility of integrating biological hydrogen and methane production in a two-stage process using mixed cultures and cheese whey powder (CWP) as substrate was studied. The effect of operational parameters such as hydraulic retention time (HRT) and organic loading rate (OLR) on the volumetric hydrogen (VHPR) and methane (VMPR) production rates was assessed. The highest VHPR was 28 L H2/L/d, obtained during stable operation in a CSTR at HRT and OLR of 6 h and 142 g lactose/L/d, respectively. Moreover, hydrogen (13 L/L/d) was produced even at HRT as low as 3.5 h and OLR of 163 g lactose/L/d, nonetheless, the reactor operation was not stable. Regarding methane production in an UASB reactor, the acidified effluent from the hydrogen-producing bioreactor was efficiently treated obtaining COD removals above 90% at OLR and HRT of 20 g COD/L/d and 6 h, respectively. The two-stage process for continuous production of hydrogen and methane recovered over 70% of the energy present in the substrate. This study demonstrated that hydrogen production can be efficiently coupled to methane production in a two-stage system and that CWP is an adequate substrate for energy production.

scholarly journals Two-Stage Biodiesel Synthesis from Used Cooking Oil with a High Acid Value via an Ultrasound-Assisted Method

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3703
Author(s):  
Ming-Chien Hsiao ◽  
Wei-Ting Lin ◽  
Wei-Cheng Chiu ◽  
Shuhn-Shyurng Hou
Keyword(s):  
Acid Value ◽  
Molar Ratio ◽  
Optimal Conditions ◽  
Two Stage ◽  
Cooking Oil ◽  
High Acid ◽  
Used Cooking Oil ◽  
Biodiesel Synthesis ◽  
Stage Process ◽  
Ultrasound Assisted

In this study, ultrasound was used to accelerate two-stage (esterification–transesterification) catalytic synthesis of biodiesel from used cooking oil, which originally had a high acid value (4.35 mg KOH/g). In the first stage, acid-catalyzed esterification reaction conditions were developed with a 9:1 methanol/oil molar ratio, sulfuric acid dosage at 2 wt %, and a reaction temperature of 60 °C. Under ultrasound irradiation for 40 min, the acid value was effectively decreased from 4.35 to 1.67 mg KOH/g, which was decreased to a sufficient level (<2 mg KOH/g) to avoid the saponification problem for the subsequent transesterification reaction. In the following stage, base-catalyzed transesterification reactions were carried out with a 12:1 methanol/oil molar ratio, a sodium hydroxide dosage of 1 wt %, and a reaction temperature of 65 °C. Under ultrasound-assisted transesterification for 40 min, the conversion rate of biodiesel reached 97.05%, which met the requirement of EN 14214 standard, i.e., 96.5% minimum. In order to evaluate and explore the improvement of the ultrasound-assisted two-stage (esterification–transesterification) process in shortening the reaction time, additional two-stage biodiesel synthesis experiments using the traditional mechanical stirring method under the optimal conditions were further carried out in this study. It was found that, under the same optimal conditions, using the ultrasound-assisted two-stage process, the total reaction time was significantly reduced to only 80 min, which was much shorter than the total time required by the conventional method of 140 min. It is worth noting that compared with the traditional method without ultrasound, the intensification of the ultrasound-assisted two-stage process significantly shortened the total time from 140 min to 80 min, which is a reduction of 42.9%. It was concluded that the ultrasound-assisted two-stage (esterification–transesterification) catalytic process is an effective and time-saving method for synthesizing biodiesel from used cooking oil with a high acid value.

scholarly journals Food behavior change in late-life widowhood: A two-stage process

Appetite ◽  
2015 ◽  
Vol 95 ◽  
pp. 399-407 ◽  
Author(s):  
Elisabeth Vesnaver ◽  
Heather H. Keller ◽  
Olga Sutherland ◽  
Scott B. Maitland ◽  
J.L. Locher
Keyword(s):  
Behavior Change ◽  
Late Life ◽  
Food Behavior ◽  
Two Stage ◽  
Stage Process
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