| 摘要 |
<p>PURPOSE:To dispose dithionate ion with extremely high efficiency using an acid in a disposal system, in a lime-gypsum process for the disposal of waste combustion gas, by recycling waste water from a gypsum-separating step to a cooling step, and decomposing waste water from the cooling step with an acid. CONSTITUTION:Waste gas generated by combustion of coal is cooled with a part 1a of supplemental water and cycled water 6 from a Ca-separating step (a), in a cooling step A, carried to an SO2-absorbing step B where SO2 is absorbed and separated from the waste gas by the remainder 1b of the supplemental water, and then discahrged. On the other hand, water is introduced through an oxidizing step C and a gypsum-separating step D to step (a) as a supernatant 3. Sodium carbonate 4 and a high-molecular flocculant 5 are added into the waste water in step (a). Ca in water 3 is converted into its carbonate and separated as precipitation from the water. The separated water is fed to step A. Waste water 2 containing dithionate ion which was generated mainly in steps B and C, is carried through a first coagulating sedimentation step (b) to a sulfuric acid-decomposing step (c), where waste water 2 is heated, mixed with sulfuric acid 9 if necessary and then heated with vapor. Consequently, the said ion is decomposed as shown in the formula. The treated waste water is then disposed with slaked lime or the like in a second coagulating sedimentation step (d).</p> |
