Papers by Keyword: Anaerobic Fermentation

Abstract: Anaerobic fermentation experiments were conducted on banana (pseudo) stem residue to study the relationship between fermentation temperature and gas production yield and gas production rate, and methane content. Based on fixed dry matter concentration, inoculum concentration and fermentation time, different temperatures, i.e. 25, 30, 35, 40°C were selected and formed four experimental groups. Four levels of single factor tests were conducted to optimize temperature parameter for anaerobic fermentation of banana stem residue. The results showed that the daily gas yield of banana stem residue reached the maximum value of 36.8L on the fourth day at 35°C, and the average gas yield was 5.03L/d. The total gas yield was 402.3L, while the maximum methane content was 61.2% in the whole fermentation process. The results indicated that the comprehensive effect was best at 35°C in anaerobic fermentation of banana stem residue.

Abstract: Rice stalk were pretreated using low concentration alkali and ultrasound combination pretreatment, biogas anaerobic fermentation were used to estimate the pretreatment. The results showed that daily mean biogas production using combined pretreatment stalk was 35.32-48.42% higher than that merely using low concentration alkali pretreatment stalk, 67.79-76.65% higher than that of unpretreated stalk. pH of fermentation broth showed no difference using different pretreatment methods. The content of lignin in lignocellulose were remarkably decreased when low concentration alkali and ultrasound combination pretreatment was used to deal with stalk, almost 41.01% lignin in stalk degraded.

Abstract: This study investigates the characteristics of an anaerobic fermentation for hydrogen yield, using sewage sludge and simulated food residues as substrates inoculate with cow manure. The moisture content was controlled at less than 80% to promote the concentration of substrates and minimize the generation of fermentation liquid, thus eliminate the subsequent treatment problem. The effects of fermentation temperature on hydrogen yield were characterized by batch fermentation between 50°C and 75°C, separated by 5°C increments. The results indicate that the 60 oC batch showed specific hydrogen yield and specific hydrogen conversion rate were relatively high, 39 mL-H2/g-VS and 4.00 g-H2/g-H of VS%, respectively. However, the average hydrogen generation rate, measured around the exponential growth phase of the batch, occurred at 65 oC batch. Furthermore, in fermentation experiments with mixed substrates at 60 oC and 65 oC series, both have an optimum mix ratio by weight, the ratio of sludge, simulated food residues and cow manure were found to be 2 : 1 : 1. Herein 60 oC series has higher cumulative volume than 65 oC series in this study. Pretreatment of the fermentation substrates by acid, alkali, heating, and agitation may affect the hydrogen fermentation characteristics. The results indicate except acid treatment poor for it, the others can enhance the hydrogen yield.

Abstract: The scaled swine farms have been developed rapidly in China since 21^st century, which bring serious problem in environmental pollution, especially in winter. In order to s reduce the pollution from intensive scaled swine farms, as well as produce biogas in winter, a technological route was put forward to control the sewage pollution in swine farm by using bio-tank of glass fiber reinforced plastics (GFRP). The experiments in swine farm of FuJian Hua Feng Co. Ltd in Nanping city showed that the developed technology had achieved zero-draining, which was able to solve the pollution problem and produce biogas in winter. The sewage temperature of bio-tank of GFRP increased average 1.18°C more than that of bio-tank of reinforced concrete. And the average biogas-generating rate of bio-tank of GFRP of year 2009 was 0.45 m³·m^-3·d^-1, which increased 28% more than that of reinforced concrete. The indexes of COD, BOD, SS, NH₃-N, and TP for the out-let wastewater of the treatment were 579.1 mg·L^-1, 237.7 mg·L^-1, 289.8 mg·L^-1, 319.4 mg·L^-1and 31.7 mg·L^-1, respectively.

Abstract: In order to improve the rate of degradation of cellulose in corn straw, the study has an important significance that compost corn straw with inoculating high-efficient microbe agents. The experiment inoculated a cellulose-degrading strain F2 which was screened from compost into compost pretreatment, the VS of corn straw reduced from 93.14% to 71.69% after 15 days, the content of cellulose reduced from 34.12g·kg-1 to 25.66g·kg-1, the rate of degradation was 24.79% which was 10.60% higher than those without the strain. An anaerobic fermentation experiment was carried out with the two groups of composted corn straw and mixed pig feces with a certain ratio, and investigations of biogas production, pH, content of volatile fatty acids(VFA) and rate of methane production were conducted. The results were that the corn straw composted with the cellulose-degrading strain peaked 4 days earlier, the maximal daily biogas production was 1470mL, the cumulative biogas production reached 23641mL which was 16.87% higher and operated stably earlier. The study showed that the cellulose-degrading strain had a strong capacity to degrade cellulose in corn straw, and then improved the performance of anaerobic digestion.

Abstract: The object of this study is to provide the scientific basis of biogas industry with agricultural residue straws as energy biomass. The biogas productivity potential experiment and reactor amplification experiment are carried out to study biogas yield from different agricultural straws including wheat straw, corn straw, peanut straw, soybean straw as well as rice straw, and the relationship between biogas yield and the anaerobic reactor volume with wheat straw as the substrate and with biogas slurry as a source of microorganisms under room temperature conditions (35°C). Micro-aerobic pretreatment fermentation technology is used to treat the agricultural straws. The batch anaerobic digestion technology and drainage collection process are used. The results show that the order of biogas yield from high to low is wheat, rice, corn, peanut and soybean straw. The utilization of peanut straw is the largest, followed by rice, corn, soybean and wheat straw. With wheat straw as the substrate amplification test reactor, gas production of 2.5 L and 1 L reactor is similar, and gas production rate and daily gas production of 2.5 L reactor is about 3 times than that of 15 L reactor.

Abstract: It was the first time to study the catalytic effect of mesoporous magnetic Fe₃O₄ nanoparticles on the biohydrogen production. The mixed culture used in this study just suffered from an alkaline shock and lost its bioactivity of hydrogen production. We use mesoporous Fe₃O₄ nanoparticles and ferrous ions as activators to recover the bioactivity of the mixed culture. The results indicate that the improvement of biohydrogen yield by mesoporous Fe₃O₄ was obvious larger than that by ferrous ions. The maximum yield of cumulative hydrogen production was obtained at the mesoporous Fe₃O₄ nanoparticles of 400 mg·L^-1, which is 26% higher than that of the blank. The lag phases for hydrogen production in the tests added with mesoporous Fe₃O₄ nanoparticles were decreased to 12 h, which are 50 h less than those of the corresponding ferrous ions and blank tests.

Abstract: Bio-hydrogen production from diluted molasses by anaerobic activated sludge was investigated in a continuous stirred-tank reactor (CSTR) under condition of continuous flow in this study. Research shows that the reactor started up under the condition of influent COD concentration 3000mg/L, HRT8h, pH6.5~7.5 and (35±1) °C. The process performed steadily and a dominant butyric acid and acetic acid type fermentation population was established, acetic acid and butyric acid accounted for about 80% in the liquid fermentation products. The effluent PH value was maintained about 5.0. The biogas yield could reach at 4.87L/d while hydrogen yield reached 41.25mL/d under the condition. When influent COD concentration rose to 5500 mg/L, the biogas yield and hydrogen yield as high as 9.45L/d and 119.98mL/d were obtained.

Abstract: Bio-methanation system was mature and has been widely utilized in South China, while hard to apply in the north. This paper aims to learn about the current situation of biogas utilization in North China, and develop the integrative biological reactor (IBR) which could make anaerobic fermentation well utilized in North China. Information was obtained via on-the-spot investigation and questionnaire survey (300 sent out, 247 effective). Through comparative analyses of the conditions, conclusions were made as follows: device’s disfunction, high cost, lack of understanding and short of materials were the main cause of the low biogas penetration rate. Experiments were made and corresponding solutions were obtained. The IBR was the integration of continuous stirred tank reactor (CSTR) and up-flow anaerobic sludge bed (UASB) reactor. Obtained from the test, when kitchen waste was used as substrate, the most suitable Volume Load Rate (VLR) for methane production was 6~8 kgCOD/(m3•d), the highest gas production rate was about 1.5~2.4L/d. And for the hydrogen production, the maximum of hydrogen production reached at 6L/d when the VLR stabilized at 15~20kgCOD/(m3d).

Abstract: Influence of different pretreatment methods applied on anaerobic mixed inoculum was evaluated for selectively enriching the hydrogen (H2) producing mixed culture using glucose as substrate. The cumulative H2 yield and H2 production rate were found to be dependent on the type of pretreatment procedure adopted on the parent inoculum. They could be increased by appropriate pretreatment methods, including use of heat, alkaline or acidic conditions. Along with the processing temperature and time of heat pretreatment and alkaline of alkali pretreatment increasing, the H2 yield increased and then declined, but it declined and then increased as the acidity of acid pretreatment increasing. Among the studied pretreatment methods, the heat pretreatment methods procedure enabled higher H2 yield and the maximum H2 production rate, then were alkali and acid pretreatment methods. When the inoculum was heat-treated at 80°C for 30 min, the highest cumulative H2 yield was obtained at 2152.0 mL, which was 53.20% higher than the control, and the maximum H2 production rate was 178.0 mL h-1, which was 122.0% higher than that of the Ctrl (138.0mL h-1).