| 摘要 |
New method to prevent the formation of black marks on the sides of sunken basins contg. water contaminated by copper ions comprises treatment with a metal sulphide with a solubility in water at least equal to that of copper sulphide. Pref. the metal sulphide is a sulphide of Cd, Pb, Co, Ni, Zn, Fe or Mn, pref. Zn. The water in the basin is circulated over a bed of particles contg. the metal sulphide in the presence of a flocculating agent (a mixture of aluminium hydroxide and aluminium chloride). The method is used for basins coated with a water-proof membrane, pref. plasticised PVC.
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