碩士 / 國立中興大學 / 環境工程學系所 / 95 / Thermophilic aerobic digestion (TAD) which applies thermotolerant microbes and their extracellular enzymes to degrade waste activated sludge (WAS) is considerably new and dynamic technique. It was mentioned that when TAD process was modified to be operated under microaerobic condition, the accumulation of volatile fatty acid (VFAs) was expected. Hydrogen production by microbes is a new technology for hydrogen production. One of the most important hydrogen producing bacteria is purple nonsulfur photosynthetic bacteria. VFAs are important substrates for purple nonsulfur bacteria to grow and produce hydrogen. Thus, combining the modified TAD process with photohydrogen production makes sludge removal and energy recycle possible.
In order to increase the accumulation concentration of VFAs in TAD reactor, first we raised the initial concentration of the SS. When initial SS concentration of sludge is 13000 mg/L, and the inoculation concentration of Geobacillus thermocatenulatus S2 was 645.4 mg/L, the accumulated concentration of VFAs was 1105 mg/L, which was the highest. The yield and C/N ratio was 0.28 mgVFAs/△mg VSS and 3.1, respectively. Second, the experiments with or without aeration was discussed. The result showed that TAD system with aeration had better reaction rate. Furthermore, the 2 L TAD reactor was operated in a continuous model at 65℃. The result indicated that when HRT is 24 hr, the accumulated concentration of VFAs was 330 mg/L, which was higher than when HRT was 12 hr.
The NH4+-N concentration of TAD effluent was too high to inhibiting the hydrogen production of purple nonsulfur bacteria. The pH value of the effluent was adjusted to be alkaline and aerated to remove ammonia. The result showed that when pH value was 12.0, NH4+-N concentration could be removed under detection limitation within 17 hr. However, when NH4+-N concentration of the TAD effluent was higher than 100 mg/L, the efficiency of aeration was low. Moreover, the VFAs concentration of the TAD effluent decreased.
Hydrogen production by Rhodopseudomonas palustris WP 3-5 using the pretreated effluent of TAD was investigated. The highest accumulated hydrogen volume was 25.8 ml (while the headspace was 50 ml) when using the TAD effluent which has already removed NH4+-N by aeration. On the other hand, we found that the distillery wastewater contained high concentration of VFAs and low concentration of NH4+-N, so we mixed the distillery wastewater with the effluent of TAD. The result showed that the best ratio of distillery wastewater to the effluent of TAD for H2 production was 2：5, and the highest accumulated H2 volume and hydrogen production rate (HPR) was 263.9 ml and 12.4 ml H2/L-culture/hr, respectively (while the headspace was 150 ml).
We also used the dilution distillery wastewater as substrate for hydrogen production. The result indicated that when content of distillery wastewater was 40%, the highest accumulated H2 volume and HPR was 278.3 ml and 13.06 ml H2/L-culture/hr, respectively. Furthermore, comparing the H2 producing efficiency of mixed wastewater and diluted distillery wastewater, it was observed that the diluted distillery had higher HPR, but the mixed wastewater had higher accumulated H2 volume.
| Identifer | oai:union.ndltd.org:TW/095NCHU5087034 |
| Date | January 2007 |
| Creators | Chia-Ling Tsai, 蔡佳玲 |
| Contributors | 李季眉 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 144 |
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