要約のみTohoku University李玉友課

Jiang Hongyu

Tohoku University博士(環境科学)博士学位論文 (Thesis(doctor))要約のみthesi

Jiang, Hongyu

Tohoku University Repository (TOUR) / 東北大学機関リポジトリ

A Comparison Study of Hydrogen Fermentation,Methane Fermentation and Hythane Fermentationof Cassava Residues著者 Jiang  Hongyu学位授与機関 Tohoku University学位授与番号 11301甲第17098号URL http://hdl.handle.net/10097/64063          しょう こうよ 氏 名          蒋   紅与 授 与 学 位          博士（環境科学） 学 位 記 番 号 環（博）第 106号 学 位 授 与 年 月 日          平成 28年 3月 25日 学位授与の根拠法規 学位規則第 4条第 1項 研究科，専攻の名称 東北大学大学院環境科学研究科（博士課程）環境科学専攻 学 位 論 文 題 目           A Comparison Study of Hydrogen Fermentation, Methane Fermentation and Hythane Fermentation of Cassava Residues  (キャッサバ廃棄物の水素発酵、メタン発酵およびハイタン発酵に 関する比較研究） 指 導 教 員 東北大学教授 李 玉友 論 文 審 査 委 員          主査 東北大学教授 李 玉友  東北大学教授 風間 聡              東北大学教授 金 放鳴  東北大学教授 西村 修                                 （工学研究科） 論 文 内 容 要 約 A series of standardized activity experiments were performed to characterize three different temperature ranges of hydrogen and methane fermentation from glucose and cellulose as sole of different carbon sources. The mesophilic mixed culture (MMC) was able to utilize the glucose or cellulose to produce methane gas under mesophilic temperature, while the thermophilic and hyper-thermophilic mixed cultures (TMC & HMC) produced only hydrogen gas in all the temperature ranges. Depending on the results of activity test, a comparison study of hydrogen fermentation, methane fermentation and hythane fermentation with or without recirculation of cassava residues was carried out to investigate the feasibility and stability of long-term continuous operation and to evaluate different dark fermentation systems from waste treatment efficiency, energy recovery efficiency and environmental impacts under the same hydraulic retention time (HRT) of 30 days. Moreover, the effects of HRTs and nutrients addition also were conducted in each continuous system to optimize the dark fermentation. 1. Introduction Nowadays, our society faces several critical problems and challenges of energy and environment. Simultaneous achievement of energy supply, environmental protection and economic growth has been required. Hydrogen and methane have been suggested as candidates for our future. A series of standardized activity experiments were carried out to characterize three different temperature ranges of hydrogen fermentation from glucose or cellulose as sole of different carbon sources (Fig. 1). Subsequently, four different systems of dark anaerobic fermentation were investigated under each own optimal temperature conditions with 10% TS of cassava residues as waste cellulosic biomass for long term operation (Fig. 2). 2. Materials and methods The substrate were cellulose (Cellulose powder E, Toyo Roshi Kaisha, Ltd. Japan), glucose for activity experiments and cassava residues (a starch processing plant in Guangxi Province, China) for continuous experiment. The seed sludge was taken from the same mesophilic anaerobic digestion treatment plant. Four continuous systems are single-stage thermophilic hydrogen fermentation system (S1), single-stage mesophilic methane fermentation system (S2), two-stage thermophilic-mesophilic hythane fermentation system (S3) and two-stage thermophilic-mesophilic hythane fermentation system with recirculation (S4). The mixed-culture sludge can show their different abilities under different operational and environmental conditions. A routine laboratory analysis and the microbial communities by 16S rRNA gene cloning and sequencing were carried out. 3. Results and discussion 3.1 Characterization and potential of Three Temperature Ranges for Hydrogen Fermentation of  Fig. 1 Design of activity test   Fig. 2 Design of four different dark continuous fermentation systems Cellulose by Means of Activity Test and 16s rRNA Sequence Analysis (Chapter 3) This chapter presented a framework to improve the economic feasibility of cellulosic biomass energy. 16S rRNA sequences analyses showed that the cellulolytic bacteria were close to Enterobacter genus in the MMC and Thermoanaerobacterium genus in the TMC and HMC. Pedobacter and Thermoanaerobacterium showed co-metabolism effect in the thermophilic range. The consumption of electrons in the production of ethanol, and the possible utilization of hydrogen in propionate formation makes both of these reaction unfavorable in the mesophilic and hyper-thermophilic ranges. The experimental results could help to improve the economic feasibility of cellulosic biomass energy using multi-stage technology to produce hydrogen, methane and hythane. 3.2 The effect of HRTs on hydrogen and acids fermentation of cassava residues (Chapter 4) A long-term continuous operation of hydrogen and acids fermentation from cassava residues was carried out to investigate the effect of HRTs on hydrogen fermentation and N-source affection under thermophilic temperature using a continuously stirred-tank reactor. The HRT of this system was set up from 30 day, 6 days to 3 day. Depending on the results from this study, we suggest that longer HRT can give higher TS and carbohydrate removal efficiency and the highest hydrogen yield of 2.38 mol H2/mol cassava residues consumed obtained under HRT of 30 days. The limiting-rate step in hydrogen fermentation is hydrolysis of cellulosic biomass. However, the COD removal efficiency in hydrogen fermentation system was too low to reach the discharge standard, due to high concentration of acids in effluent, so methane or two-stage fermentation should be studied. 3.3 Improvement of Cassava Residues to Bio-energy Conversion Efficiency by Changing Single-stage Methane into Two-stage Hythane Fermentation (Chapter 5) Two main experimental parts were conducted, which were a continuous single-stage mesophilic methane fermentation under HRT of 30 days and the improvement by changing single-stage into two-stage hythane fermentation under the same HRT. The COD removal efficiency in two-stage hythane fermentation was 74.8%, which increased 6.2% comparing with that in single-stage methane fermentation. The first-stage works as pretreatment process. The continuous two-stage hydrogen-methane fermentation of cassava residues can effectively improve energy production and waste reduction. 3.4 The Effects of Hydraulic Retention Time and Nutrients on Continuous Thermophilic-mesophilic Two-stage Hydrogen-methane Fermentation of Cassava Residues with Recirculation (Chapter 6) The continuous hythane fermentation of cassava with 1:1 recirculation ratio was conducted under different HRTs (200, 100, 50, 37.5 and 30 day). Moreover, N-source addition in continuous experiment of hythane fermentation and nickel, cobalt and sulfur affection on repeated batch experiments and continuous experiment of methane fermentation were carried out. The hythane fermentation of cassava residues under continuous operation without the addition of nutrients resulted in an unstable performance for long-term operation, which was characterized by a radical decrease in the methane production along with a drop in the methane content. The results of the repeated batch experiment and continuous experiment demonstrated the sufficient nutrients addition can recover and enhance hythane fermentation effectively. 4. Conclusion (Chapter 7) The comparison study on four different systems pointed out that two-stage hythane fermentation of cassava residues with recirculation was the optimal system, which was able to keep stability of high waste treatment efficiency and energy recovery efficiency with low environmental impacts. For future work, researchers should deeply study the environmental/operational factors for continuous reactor in order to match industrialized scale. Due to cellulose is hard to hydrolysis; the pretreatment of cellulosic biomass also should be the direction of future studying. Other real cellulosic wastes, such as waste paper, rice straw, and cornstalk should be used in continuous reactor, to examine the effectiveness. References [1] Jiang, H., Gadow, S. I., Tanaka, Y., Cheng, J., & Li, Y. Y. (2015). Improved cellulose conversion to bio-hydrogen with thermophilic bacteria and characterization of microbial community in continuous bioreactor. Biomass and Bioenergy, 75, 57-64. [2] Gadow, S. I., Li, Y. Y., & Liu, Y. (2012). Effect of temperature on continuous hydrogen production of cellulose. International Journal of Hydrogen Energy, 37(20), 15465-15472. 

A Comparison Study of Hydrogen Fermentation, Methane Fermentation and Hythane Fermentation of Cassava Residues

https://tohoku.repo.nii.ac.jp/?action=repository_action_common_download&item_id=72145&item_no=1&attribute_id=18&file_no=1

キャッサバ廃棄物の水素発酵、メタン発酵およびハイタン発酵に関する比較研究

Abstract

Similar works

Full text

Available Versions

Tohoku University Repository (TOUR) / 東北大学機関リポジトリ