| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and apparatus for treating wastewater which enables crystallization treatment without addition of an agent for crystallization, and enables a stable operation at a high concentration rate without external addition of a calcium softening agent in subsequent distillation concentration since the concentration of components to be crystallized in the wastewater is reduced by the crystallization treatment. SOLUTION: Wastewater containing the components to be crystallized is subjected to treatment combining the distillation concentration treatment and crystallization treatment. A part of concentrated wastewater obtained by the distillation concentration is taken outside of a system, and the remainder is introduced to a crystallization process, and crystallized to take out crystallized material. In the combined treatment, the concentration of the components to be crystallized in the wastewater flowing into a distillation concentration apparatus is reduced by the crystallization treatment, which enables the high concentration rate of the distillation concentration. Distillation concentrate with a high concentration of the components to be crystallized is substituted for the addition of the agent for crystallization, required for the crystallization treatment, which enables the crystallization treatment without the addition of the agent for crystallization. COPYRIGHT: (C)2007,JPO&INPIT
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