| Summary: | 碩士 === 臺中師範學院 === 環境教育研究所 === 90 === Different kinds of anaerobic biological treatment processes can be used to treat different types of organic wastewater and result in very good treatment efficiency after complete reaction. However, if the produced methane does not be utilized and escape into the atmosphere, serious green-house effect will be increased. Furthermore, hydrogen-fermentation also in anaerobic processes will not result in the above problem.
This research is based on the wastewater anaerobic biological treatment experiences, considering physiological characteristics and the required growth environment of anaerobic hydrogen-fermentative bacteria. Four different kinds of reactors are employed, including sludge recycling reactor, continuous stirred-tank reactor (CSTR) , conventional reactor and plug flow reactor. There are two main purposes in this research: The first purpose include start-up of four different kinds of reactors, effects of influent organic strength, hydraulic retention time in order to establish the optimal operating conditions, kinetics, process control and model simulation of anaerobic hydrogen-fermentative process, and hydrogen productivity. The second purposes include various operational conditions, that is pH , temperature and ORP of CSTR, in order to establish the pattern control model and promote hydrogen productivity.
The study reveals that when the influent COD concentrations of 2,000~15,000 mg/L and the hydraulic retention times are 6,12,20,24,36 hrs., hydrogen productivity of the four different kinds of reactors is promoted with the increase of the influent COD concentration and the decrease of the HRT. The influence of HRT on hydrogen productivity is more greater than the influent COD concentration. Among these four reactors, the CSTR is the most suitable one for anaerobic hydrogen-fermentation process, the second one is the conventional reactor. The sludge recycling reactor brings about the better result of hydrogen productivity only in the case that there are more biogas because of organic loading. The conditions of the three reactors are as following: the influent COD concentration of 8,000 mg/L, the HRT 6 hours, the H2/H2+CH4 and hydrogen productivity (mole-H2/m3·day) of those reactor are respectively 55.3﹪and 44.31mole, 26.4﹪and 19.64mole, 22.7﹪and 28.82 mole. Because of the main ingredients of the synthetic organic wastewater are glucose and beef extract, Gompertz equation, that used in batch experiment, is not adopted. The regression result performed the Monod equation is fit for this study.
The study of CSTR was performed for influent COD concentration of 10,000 mg/L under HRT of 4 hrs. The hydrogen productivity of CSTR is promoted with the increase of the temperature and the decrease of pH and ORP. The best hydrogen productivity (mmole-H2/g-CODre and mole-H2/m3·day) of CSTR is 6.05mmole and 41.91mole on 43℃, 5.37mmole and 32.98mole on pH 4.5, 5.61mmole and 39.61 mole on -500mv.
Observed through the fluorescence microscope and the scanning electron microscope, here comes the results as presented : The better hydrogen productivity is, the brighter orange-yellow light shines; on the contrary, the worse efficiency, the brighter blue light, showing that methanogeneration is stronger. The results here can help us how to promote the hydrogen productivity.
The formula of the hydrogen productivity and process control model of CSTR was shown as following: Hydrogen productivity (mole-H2/m3·day）=[1.084(loading）+0.500)]·1.071（T-20）·0.6424（pH-4.5）·0.6786（ORP -(-500) ）/100.
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