The relations between CST-value and specific resistance, filtration velosity etc, were examined in the benti-scale test. CST-value was made clear to have good correlations with specific resistance and filtration velosity. The correction procedure was deduced with sludge concentration and temperature. Corrected CST-value is a good index of filtrability.
The dairy and yearly variation of the sludge filtrability was also examined in the practical dewatering plant.

View full abstract

The behaviors of NO_x and NH₃ in the UV reaction of NO-NH₃-O₂-N₂ mixture were studied at room temperature. The decomposition rate of NH₃ under a high pressure mercury lamp irradiation was proportional to the concentration of NH₃ and was not affected by the presence of NO and O₂. NO reacted with NH₂ formed by the dissociation of NH₃ to form N₂ and was partially oxidized to NO₂. A small amount of N₂O formed as by-product similarly in the case of the absence of NO. The decomposition rate of NO_x was nearly equal to that of NH₃. Under a low pressure mercury lamp irradiation, the decomposition rate of NH₃ increased by the presence of NO and O₂. The rate increased with the increasing of the concentration of O₂. The promotion effect of NO on the NH₃ decomposition decreased with the increasing of the concentration of O₂, while no effect of NO was observed at 10 % of O₂. About 22 % of NH₃ changed to N₂O at 10 % of O₂ and a part of NO was oxidized to NO₂. NO reacted mainly with NH₃ and decomposed to N₂ and H₂O rapidly. The initial decomposition rates of NH₃ and NO_x under a low pressure mercury lamp irradiation were 10 times larger than those under a high pressure mercury lamp irradiation, and the decomposition rate of NH₃ was about 1.3 times of that of NO_x because of the change to N₂O.

View full abstract

[in Japanese]

View full abstract