ハイスイ ショリ ニオケル セイブツガクテキ リン ジョキョ システム オ コウセイ スル ビセイブツ コタイグン ノ カイセキ

筑波大学博士 (農学) 学位論文・平成11年3月25日授与 (甲第2046号)標題紙、目次 -- 第１章　諸論 -- 第２章　リン蓄積細菌 Microlunatus phosphovorus のリン取り込み・放出特性 -- 第３章　リン蓄積細菌 M. phosphovorus に特異的な蛍光標識オリゴヌクレオチドプローブの作製とプローブを用いた活性汚泥中の M. phosphovorusの検出　 -- 第４章　各種微生物系統群に特異的な蛍光標識オリゴヌクレオチドプローブとポリリン酸染色性蛍光色素DAPIを使用したベンチスケールリアクターにおけるリン蓄積細菌群の解析 -- 第５章　各種微生物系統群に特異的な蛍光標識オリゴヌクレオチドプローブとポリリン酸染色性蛍光色素を使用した実処理施設におけるリン蓄積細菌群の解析 -- 第６章　フラーサイトメトリーを利用したリン蓄積細菌の分離と系統解析 -- 第７章　まとめ -- 謝辞 -- 文

Non-oxidative coupling of methane over Pd-loaded gallium oxide photocatalysts in a flow reactor

Photocatalytic methane conversion is attractive for utilization of renewable biogas and solar energy to directly produce useful compounds. In the present study, gallium oxide (Ga2O3) photocatalyst was examined for non-oxidative coupling of methane (NOCM) around room temperature in a flow reactor. It was found that ethane and hydrogen were continuously yielded at constant rates from methane upon photoirradiation around room temperature, confirming that NOCM can be promoted photocatalytically over Ga2O3. In addition, Pd cocatalyst was found to improve the activity of the Ga2O3 photocatalyst for NOCM to produce ethane and hydrogen at almost the same constant rate and achieve more than three times higher formation rate of ethane such as 0.22 μmol h−1 in a flow of 10% methane at 30 mL min−1 with 0.8 g of photocatalyst. The methane conversion achieved to 0.006% within a short contact time of 0.8 s, which is higher than the thermodynamic equilibrium conversion

Long-term population dynamics and in situ physiology in activated sludge systems with enhanced biological phosphorus removal operated with and without nitrogen removal

Quantitative fluorescence in situ hybridization (FISH) and the combination of FISH with microautoradiography (MAR) were used in order to study the long-term population dynamics (2.5 years) and the in situ physiology in two parallel activated sludge pilot systems with enhanced biological phosphorus removal (EBPR). The two systems received the same influent wastewater, but were differently operated (with and without nitrogen removal, respectively). Both systems showed a significant P removal that increased when different substrates (phosphorus (P), acetate and glucose, respectively) were added to the influent wastewater. Rhodocyclus-related bacteria were present in both systems in significant numbers (ranging from 4 to 28%) throughout the whole period. This supports the hypothesis that these bacteria occur in significant numbers in different types of well-operating EBPR activated sludge processes. However, we observed a lower correlation (0.9). The Actinobacteria were the only additional group of bacteria which showed a similar degree of correlation to the P content in activated sludge as the Rhodocyclus-related bacteria - but only for the system without nitrogen removal. Significant amounts (less than or equal to12%) of glycogen-accumulating bacteria (GAOs) were detected in the system with nitrogen removal (but not in the other system), but had no, in contrast to previous observations, apparent negative effect on the overall EBPR performance. FISH-MAR indicated that a significant part of the Betaproteobacteria (part of them identified as Rhodocyclus-related bacteria) as well as the Actinobacteria were able to take up P-33(i), [H-3]-acetate and [H-3]-glucose under anaerobic-aerobic conditions. The contribution of anoxic P-33(i) uptake under alternating anaerobic-anoxic conditions was significantly lower. Interestingly, not all Rhodocyclus-related bacteria showed uptake of these three radioactive substrates. This may be due to differences in metabolic state, physiological potential or genotype, not detectable by the present probe set for Rhodocyclus-related bacteria. Comparison of the P-33(i), [H-3]-acetate and [H-3]-glucose uptake by activated sludge after different fixation and incubation procedures showed that a part of the observed P-33(i), uptake may have been caused by a combination of a biological and chemical or biologically induced chemical P adsorption

Population changes in a biofilm reactor for phosphorus removal as evidenced by the use of FISH

Induction of denitrification was investigated for a lab-scale phosphate removing biofilm reactor where oxygen was replaced with nitrate as the electron acceptor. Acetate was used as the carbon source. The original biofilm (acclimatised with oxygen) was taken from a well-established large-scale reactor. During the first run, a decrease in the denitrifying bio-P activity was observed after 1 month following a change in the anaerobic phase length. This was initially interpreted as a shift in the microbial population caused by the changed operation. In the second run, biomass samples were regularly collected and analysed by fluorescent in situ hybridisation (FISH) and confocal laser scanning microscopy (CLSM). Concurrently, samples were taken from the original reactor with oxygen as electron acceptor in order to investigate natural microbial fluctuations. A similar decrease in the activity as in the first run was seen after one month, although the phase lengths had not been varied. Hence, the decrease after 1 month in the first and second run should be seen as a start-up phenomenon. FISH could detect a noticeable shift in the microbial population mainly within the first 2 weeks of operation. Almost all bacteria belonging to the alpha subclass disappeared and characteristic clusters of the beta and gamma subclasses were lost. Small clusters of gram-positive bacteria with a high DNA G+C content (GPBHGC) were gradually replaced by filamentous GPBHGC. Most of the bacteria in the denitrifying, phosphate removing biofilm belonged to the beta subclass of Proteobacteria. The applied set of gene probes had been selected based on existing literature on biological phosphate removing organisms and included a recently published probe for a Rhodocyclus-like clone. However, none of the specific probes hybridised to the dominant bacterial groups in the reactors investigated. No noticeable changes were detected in the aerobic bench-scale reactor during this period, indicating that the observed changes in the lab-scale reactor were caused by the changed environment