The experiments were carried out in continuous flow acidogenic reactors with molasses used as substrate to study the effects of pH and redox potential on fermentation types. The conditions for each fermentation type w...The experiments were carried out in continuous flow acidogenic reactors with molasses used as substrate to study the effects of pH and redox potential on fermentation types. The conditions for each fermentation type were investigated at different experimental stages of start up, pH regulating and redox potential regulating. The experiments confirmed that butyric acid type fermentation would occur at pH > 6, the propionic acid type fermentation at pH about 5.5 with E h> -278 mV, and the ethanol type fermentation at pH < 4.5. A higher redox potential will lead to propionic acid type fermentation because propionogens are facultative anaerobic bacteria.展开更多
This work evaluated the effects of sodium ion concentration, ranging from 0 to 16000mg·L^-1（Na^＋）, on the conversion of sucrose to hydrogen by a high-activity anaerobic hydrogen-producing granular sludge. At ...This work evaluated the effects of sodium ion concentration, ranging from 0 to 16000mg·L^-1（Na^＋）, on the conversion of sucrose to hydrogen by a high-activity anaerobic hydrogen-producing granular sludge. At the optimum sodium ion concentration [1000-2000mg·L^-1（Na^＋）] for hydrogen production at 37℃, the maximum sucrose degradation rate, the specific hydrogen production yield and the specific hydrogen production rate were 393.6-413.1mg·L^-1.h^-1, 28.04-28.97ml·g^-1, 7.52-7.83ml·g^-1.h^-1, respectively. The specific production yields of propionate, butyrate and valerate decreased with increasing sodium ion concentration, whereas the specific acetate production yield increased, meanwhile the specific production yields of ethanol and caproate were less than 55.3 and 12.6mg·g^-1, respectively. The hybrid fermentation composition gradually developed from acetate, propionate and butyrate to acetate with the increase in sodium ion concentration.展开更多
文章实验采用产酸相中温产甲烷相高温两相发酵工艺,逐步提高系统中有机负荷,以此研究产甲烷相中氨氮浓度的变化规律及其影响。结果表明:氨氮浓度随有机负荷的提高而增大,当有机负荷提高到7.3 g VS·L-1d-1时,氨氮浓度上升到5386 mg&...文章实验采用产酸相中温产甲烷相高温两相发酵工艺,逐步提高系统中有机负荷,以此研究产甲烷相中氨氮浓度的变化规律及其影响。结果表明:氨氮浓度随有机负荷的提高而增大,当有机负荷提高到7.3 g VS·L-1d-1时,氨氮浓度上升到5386 mg·L-1,容积产气率最高达4.1 L·L-1d-1,系统运行良好;当有机负荷达到7.7 g VS·L-1d-1时,氨氮浓度达到6144 mg·L-1,系统出现氨氮抑制;抑制解除后,系统可在有机负荷为3.4 g VS·L-1d-1,氨氮浓度为4586 mg·L-1的条件下稳定运行,容积产气率达到2.5 L·L-1d-1。实验结果还显示:在高浓度氨氮条件下可强化乙酸的代谢,但对丙酸和丁酸的效果不明显。展开更多
A lab-scale expanded granular sludge bed （EGSB） reactor was employed to evaluate the feasibility of the hydrogen energy recovery potential from high strength organic wastewater. The results showed that a maximum hyd...A lab-scale expanded granular sludge bed （EGSB） reactor was employed to evaluate the feasibility of the hydrogen energy recovery potential from high strength organic wastewater. The results showed that a maximum hydrogen production rate of 7.43 m^3 H2/m^3 reactor · d and an average hydrogen production rate of 6.44- ms H^2/ms reactor · d were achieved with the hydrogen content of 50% -56% in the biogas during the 90-day operation. At the acidogenic phase, COD removal rate was stable at about 15%. In the steady operation period, the main liquid end products were ethanol and acetic acid, which represented ethanol type fermentation. Among the liquid end products, the concentration percentage of ethanol and acetic acid amounted to 69.5% - 89. 8% and the concentration percentage of ethanol took prominent about 51.7% - 59. 1%, which is better than the utilization of substrate for the methanogenic bacteria. An ethanol type fermentation pathway was suggested in the operation of enlarged industrial continuous hydrogen bio-producing reactors.展开更多
Succinic acid is one of the most useful intermediate chemicals that can be produced in a biorefinery approach.In this study,Actinobacillus succinogenes was immobilized to produce succinic acid using non-detoxified cor...Succinic acid is one of the most useful intermediate chemicals that can be produced in a biorefinery approach.In this study,Actinobacillus succinogenes was immobilized to produce succinic acid using non-detoxified corn fiber hydrolysate(CFH)and a control mimicking the sugars in CFH.Tests were carried out in a hollow fiber membrane packed-bed biofilm reactor(HFM–PBR)operated in a continuous mode.Under steady-state conditions,the bioconversion process was characterized in terms of sugar consumption,succinic acid and other organic acid production.Steady states were obtained at dilution rates of 0.025,0.05,0.075,0.1,0.2,and 0.3 h^(-1).The optimal results were achieved at the dilution rate of 0.05 h^(-1)and recirculation rate of 50 ml/min with a maximum succinic acid concentration,yield and productivity of 31.1 g/L,0.61 g/g and 1.56 g/L h,respectively,when control was used.Succinic acid concentration,yield and productivity of 23.4 g/L,0.51 g/g and 1.17 g/L h,respectively,were obtained when CFH was used.Productivity in the HFM–PBR was between 1.3 and 1.9 times higher than productivities for succinic acid production from CFH stated in the literature.The results demonstrated that immobilized A.succinogenes has the potential for effective conversion of an inexpensive biomass feedstock to succinic acid.Furthermore,the process has the potential to serve as a means for value-added chemical biomanufacturing in an integrated corn biorefinery.展开更多
文摘The experiments were carried out in continuous flow acidogenic reactors with molasses used as substrate to study the effects of pH and redox potential on fermentation types. The conditions for each fermentation type were investigated at different experimental stages of start up, pH regulating and redox potential regulating. The experiments confirmed that butyric acid type fermentation would occur at pH > 6, the propionic acid type fermentation at pH about 5.5 with E h> -278 mV, and the ethanol type fermentation at pH < 4.5. A higher redox potential will lead to propionic acid type fermentation because propionogens are facultative anaerobic bacteria.
基金Supported by the National Natural Science Foundation of China （No.20122203）.
文摘This work evaluated the effects of sodium ion concentration, ranging from 0 to 16000mg·L^-1（Na^＋）, on the conversion of sucrose to hydrogen by a high-activity anaerobic hydrogen-producing granular sludge. At the optimum sodium ion concentration [1000-2000mg·L^-1（Na^＋）] for hydrogen production at 37℃, the maximum sucrose degradation rate, the specific hydrogen production yield and the specific hydrogen production rate were 393.6-413.1mg·L^-1.h^-1, 28.04-28.97ml·g^-1, 7.52-7.83ml·g^-1.h^-1, respectively. The specific production yields of propionate, butyrate and valerate decreased with increasing sodium ion concentration, whereas the specific acetate production yield increased, meanwhile the specific production yields of ethanol and caproate were less than 55.3 and 12.6mg·g^-1, respectively. The hybrid fermentation composition gradually developed from acetate, propionate and butyrate to acetate with the increase in sodium ion concentration.
文摘文章实验采用产酸相中温产甲烷相高温两相发酵工艺,逐步提高系统中有机负荷,以此研究产甲烷相中氨氮浓度的变化规律及其影响。结果表明:氨氮浓度随有机负荷的提高而增大,当有机负荷提高到7.3 g VS·L-1d-1时,氨氮浓度上升到5386 mg·L-1,容积产气率最高达4.1 L·L-1d-1,系统运行良好;当有机负荷达到7.7 g VS·L-1d-1时,氨氮浓度达到6144 mg·L-1,系统出现氨氮抑制;抑制解除后,系统可在有机负荷为3.4 g VS·L-1d-1,氨氮浓度为4586 mg·L-1的条件下稳定运行,容积产气率达到2.5 L·L-1d-1。实验结果还显示:在高浓度氨氮条件下可强化乙酸的代谢,但对丙酸和丁酸的效果不明显。
文摘A lab-scale expanded granular sludge bed （EGSB） reactor was employed to evaluate the feasibility of the hydrogen energy recovery potential from high strength organic wastewater. The results showed that a maximum hydrogen production rate of 7.43 m^3 H2/m^3 reactor · d and an average hydrogen production rate of 6.44- ms H^2/ms reactor · d were achieved with the hydrogen content of 50% -56% in the biogas during the 90-day operation. At the acidogenic phase, COD removal rate was stable at about 15%. In the steady operation period, the main liquid end products were ethanol and acetic acid, which represented ethanol type fermentation. Among the liquid end products, the concentration percentage of ethanol and acetic acid amounted to 69.5% - 89. 8% and the concentration percentage of ethanol took prominent about 51.7% - 59. 1%, which is better than the utilization of substrate for the methanogenic bacteria. An ethanol type fermentation pathway was suggested in the operation of enlarged industrial continuous hydrogen bio-producing reactors.
基金The authors wish to acknowledge the Nebraska Corn Board for funding this work under award number 88-R-1718-01the financial support of the University of Nebraska-Lincoln Agricultural Research Division.
文摘Succinic acid is one of the most useful intermediate chemicals that can be produced in a biorefinery approach.In this study,Actinobacillus succinogenes was immobilized to produce succinic acid using non-detoxified corn fiber hydrolysate(CFH)and a control mimicking the sugars in CFH.Tests were carried out in a hollow fiber membrane packed-bed biofilm reactor(HFM–PBR)operated in a continuous mode.Under steady-state conditions,the bioconversion process was characterized in terms of sugar consumption,succinic acid and other organic acid production.Steady states were obtained at dilution rates of 0.025,0.05,0.075,0.1,0.2,and 0.3 h^(-1).The optimal results were achieved at the dilution rate of 0.05 h^(-1)and recirculation rate of 50 ml/min with a maximum succinic acid concentration,yield and productivity of 31.1 g/L,0.61 g/g and 1.56 g/L h,respectively,when control was used.Succinic acid concentration,yield and productivity of 23.4 g/L,0.51 g/g and 1.17 g/L h,respectively,were obtained when CFH was used.Productivity in the HFM–PBR was between 1.3 and 1.9 times higher than productivities for succinic acid production from CFH stated in the literature.The results demonstrated that immobilized A.succinogenes has the potential for effective conversion of an inexpensive biomass feedstock to succinic acid.Furthermore,the process has the potential to serve as a means for value-added chemical biomanufacturing in an integrated corn biorefinery.
