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
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 m3 H2/m3 reactor·d and an average hydrogen production rate of 6.44 m3 H2/m3 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
Series batch experiments were made to investigate the influences of pH and temperature on the activity of acidogenus and acidogenus in glucose-degrading bacteria cultured in an UASB(up-flow anaerobic sludge blanket) r...Series batch experiments were made to investigate the influences of pH and temperature on the activity of acidogenus and acidogenus in glucose-degrading bacteria cultured in an UASB(up-flow anaerobic sludge blanket) reactor for glucose fermentation and hydrogen production. The bacteria exhibited different capability to recover to produce hydrogen at different initial pH and temperature. Hydrogen production, VFA production, COD removal and COD balance were measured at different pH and 20, 37 ℃ respectively with the same glucose and VSS in vials. Results showed that there are different influences on the activity of acidogenic bacteria at varied pH and result in a variety of amount of hydrogen production, specific hydrogen production and VFA production, etc. Through the present study, when nonmalized to the weight of VSS, a maximal biogas and hydrogen production of 1 717 1 ml/g and 870 0 ml/g were obtained when pH equals 9 at 37 ℃ and 679 00 ml/g of biogas, 246 35 ml/g of hydrogen were also got when pH equals 5 at 20 ℃ respectively. The maximal specific hydrogen production (SHA) was 116 56 ml/h,g around 8 of pH value at 37 ℃ and 6 46 ml/h,g around 4 of pH value at 20 ℃, which were obtained by calculating the slope of the accumulated hydrogen gas via time. Butyric acid fermentation was important for hydrogen production. Large quantity of unknown COD was found in the vials when a small quantity of bio-gas was produced, but relative less unknown COD was determined when there was large quantity of hydrogen produced. This revealed a better engineering foreground for application of hydrogen bio-production.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.
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 m3 H2/m3 reactor·d and an average hydrogen production rate of 6.44 m3 H2/m3 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.
文摘Series batch experiments were made to investigate the influences of pH and temperature on the activity of acidogenus and acidogenus in glucose-degrading bacteria cultured in an UASB(up-flow anaerobic sludge blanket) reactor for glucose fermentation and hydrogen production. The bacteria exhibited different capability to recover to produce hydrogen at different initial pH and temperature. Hydrogen production, VFA production, COD removal and COD balance were measured at different pH and 20, 37 ℃ respectively with the same glucose and VSS in vials. Results showed that there are different influences on the activity of acidogenic bacteria at varied pH and result in a variety of amount of hydrogen production, specific hydrogen production and VFA production, etc. Through the present study, when nonmalized to the weight of VSS, a maximal biogas and hydrogen production of 1 717 1 ml/g and 870 0 ml/g were obtained when pH equals 9 at 37 ℃ and 679 00 ml/g of biogas, 246 35 ml/g of hydrogen were also got when pH equals 5 at 20 ℃ respectively. The maximal specific hydrogen production (SHA) was 116 56 ml/h,g around 8 of pH value at 37 ℃ and 6 46 ml/h,g around 4 of pH value at 20 ℃, which were obtained by calculating the slope of the accumulated hydrogen gas via time. Butyric acid fermentation was important for hydrogen production. Large quantity of unknown COD was found in the vials when a small quantity of bio-gas was produced, but relative less unknown COD was determined when there was large quantity of hydrogen produced. This revealed a better engineering foreground for application of hydrogen bio-production.
文摘针对废水两相厌氧处理系统中产酸相反应器的乙醇型发酵启动速度较慢,污泥易流失的不足,本文采用在产酸相反应器中接种厌氧颗粒污泥,同时控制启动容积负荷、负荷提高幅度、碱度等运行参数,对反应器乙醇型发酵的形成情况进行考察.通过监测液相末端产物、pH、ORP、酸化度等指标来考察反应器的运行情况,结果表明:反应器在34 d内完成由混合酸发酵-丁酸型发酵-乙醇型发酵的演替过程.启动结束时,乙醇+乙酸质量质量浓度之和占液相末端产物总量的75.9%以上;pH值稳定在4.1～4.3;ORP值稳定在-230～-250 mV;接种的厌氧颗粒污泥性质发生明显变化,其表观颜色逐渐由黑色和灰黑色变为土黄色和黄褐色,粒径明显减小,多在0.50～1.25 mm.
