| 摘要 |
<p>PROBLEM TO BE SOLVED: To develop and provide a technique which uses waste gypsum in a waste gypsum board, makes a calcium phosphate compound formed of sewage sludge intermediate treatment liquid including phosphorus a heavy metal removal agent, removes heavy metal in waste water efficiently and is utilized as a heavy metal removal agent needing low cost.SOLUTION: A waste gypsum board (1) is crushed, and a board (2) is removed for forming a powder-state waste gypsum powder (X). Then, using the waste gypsum powder, reaction with the waste gypsum powder and a solution (Y) including phosphoric acid (3) with high density is performed for constant time, after adding the waste gypsum powder directly or adding the slurry-state waste gypsum to the solution so that the amount of the waste gypsum powder is slightly excess to a content of phosphorus, then precipitate is collected and separated for acquiring a calcium phosphate compound (Z).</p> |
