Flow patterns of anaerobic digestion solution in four shapes of digesters were studied on the various case of mixing methods to evaluate the difference of digestionability due to the shapes of digesters, and construction procedures, structural stabilities and construction costs of three digestion tank were investigated.
These results showed that the oval shape was the most suitable digester for anerobic reaction process.

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A kinetic study on pH of the water phase arising from reaction of a shale and water was made over periods of minutes to hours at 25°C under the nitrogen-gas. The changes in pH of the water phase was expressed by the empirical function with terms of cation exchange reaction of minerals, and the function was identical with a theoretical one derived from a surface reaction controlled by the following mechanism. (i) The first stage of the process is the entering of hydrogen ion from water into the crystal lattice of the mineral surface. (ii) A cation in the lattice is ejected out into the water by the electrostatically repulsive force from the possitive charge on the invading hydrogen ion.
Derivation and application of the theoretical function to natural water were discussed.

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