| 摘要 |
<p>Water used in the treatment of waste paper is now commonly re-cycled. Hard water is required for such processes. For maintaining the hardness of the water, the re-cycled water is hardened by dissolving calcium carbonate and carbon dioxide in it, thereby forming calcium bicarbonate. An apparatus for hardening the water comprises a mixing container with inlets for waste water, carbon dioxide, and calcium carbonate, and with outlets for foam, hardened water and undissolved calcium carbonate.</p> |
