Bioaugmentation treatment of a two-phased thermophilic anaerobic digestion system treating organic wastes

Autor: Hao-Wei Wu, 吳晧瑋
Rok vydání: 2012
Druh dokumentu: 學位論文 ; thesis
Popis: 100
Student ID: M9931001 Title of Thesis: Bioaugmentation treatment of a two-phased thermophilic anaerobic digestion system treating organic wastes Total Pages: 203 Name of Institute: National Pingtung University of Science and Technology Name of Department: Department of Environmental Science and Engineering Date of Graduation: August, 2012 Degree Conferred: Master Name of Student: Hao-Wei Wu Adviser: Dr. Wen-Chien Kuo The Contents of Abstract in this Thesis： This study aims at the bioaugmentation treatment of a two-phased thermophilic anaerobic digestion system. Napiergrass and leafy kitchen waste were used to produce hydrogen and methane. Molecular biotechnology was applied to monitor existence of the bioaugmented culture, TCW1. A laboratory-scaled, semi-CSTR thermophilic anaerobic digestion system was used in this study. Volume of the acidogenic tank is 3L with a daily feed of 0.5L. Volume of the methanogenic tank is 10L with a daily feed of 0.5L. Hydraulic retention times (HRTs) and organic load rates (OLRs) in the acidogenic and methanogenenic tanks are 6 and 20 days, and 13 and 4 g COD/L-d, respectively. Temperatures were controlled at 55oC for both tanks, reactor pH and ORP were monitored daily, and pHs were controlled at 5.5 and 7.5 in acidogenic and methanogenenic tanks, respectively. A mobile system was used for the pilot-scale study. Volumes of the acidogenic and methanogenic tanks are 900L and 4000L, respectively. The daily feed to the mobile system is 200L, and this gives the HRTs of 4.5 and 20 days in the acidogenic and methanogenenic tanks, respectively. OLRs in the acidogenic and methanogenenic tanks are 17.8 g and 4 g COD/L-d, respectively. Temperatures were controlled at 55oC for both tanks, reactor pH and ORP were monitored daily, and pHs were controlled at 5.5 and 7.5 in the acidogenic and methanogenic tanks. Investigation in the laboratory was divided into three stages. In the first stage, COD from leafy kitchen waste plus TCW1 vs. napiergrass was set at 1:3. TCOD, SS, and cellulose removal efficiencies in acidogenenic and methanogenenic tanks were 13.32±5.54% and 60.91±9.57%, 12.32±19.19% and 63.88±20.65%, 16.07±6.13% and 55.37±9.61%, respectively. Average percentage of hydrogen produced in acidogenic tank was16.44±1.09%, with an average gas production rate of 0.16±0.03 H2 L/d. Average percentage of methane in the methanogenic tank was 54.84±1.86%, with an average methane production rate of 5.71±1.04 CH4 L/d. In the second stage, COD from leafy kitchen waste plus TCW1 vs. napiergrass was set at 3:1. In this stage, TCOD, SS, and cellulose removal efficiencies in acidogenic and methanogenic tanks were 16.85±5.44% and 62.94±3.76%, 20.12±12.96% and 59.72±17.30%, and 23.59±10.98 and 54.89±9.29%, respectively. Average percentage of hydrogen production in acidogenesis tank was 35.58±2.88%, with an average gas production rate of 0.94±0.16 H2 L/d. Average percentage of methane in the methanogenesis tank was 63.39±0.96%, with an average methane production rate 8.43±0.76 CH4 L/d. In the third stage, COD from leafy kitchen waste vs. napiergrass was set at 3:1 (no TCW1 was added). In this stage, TCOD, SS, and cellulose removal efficiencies in acidogenic and methanogenic tanks were 8.14±2.58% and 61.69±6.52%, 13.38±5.53% and 70.96±6.71%, and 15.95±6.38 and 71.95±4.99%, respectively. Average percentage of hydrogen production in acidogenic tank was 24.88±5.99%, with an average gas production rate of 0.46±0.08H2 L/d. Average percentage of methane in the methanogenic tank was 62.15±6.54%, with an average methane production rate 6.7421±1.18 CH4 L/d. Study in the mobile system was divided into two stages. In the first stage, influent COD was from kitchen waste only. TCOD, SS removal efficiencies in acidogenic and methanogenic tanks were 14.37±11.05% and 46.07±7.12%, 20.75±5.68% and 52.08±4.39%, Average percentage of methane in the methanogenic tank was 53.2%, with an average methane production rate of 731±373 CH4 L/d. In the second stage, COD from kitchen waste vs. napiergrass was set at 3:1. In this stage, TCOD, SS removal efficiencies in acidogenesis and methanogenesis tanks were 3.62% and 45.03%, and 15.49% and 53.56%, respectively. Average percentage of methane in the methanogenic tank was 41.6%, with an average methane production rate 701±252 CH4 L/d. Molecular biotechnology of PCR-DGGE was applied for the identification of TCW1 in the laboratory study. The TCW1 was found to survive in the first stage. In the second stage, there was no TCW1 can be found in the acidogenic tank. Possible explanation was that DNA samples was kept too long in the temperature of -20 ℃ and this led to a failure in the extraction of PCR. Nevertheless, this bioaugmented TCW1 was found at the first and second stage in the methanogenic tank, but not found in the third stage. Keywords：Thermophilic anaerobic digestion, Cellulose, Bioaugmentation, PCR-DGGE.
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