| 摘要 |
<p>A process for the regeneration of iron oxyhydroxide-based filtration material for arsenic, characterised by:
- passing through the filtration material (4) a flow of sulphuric acid of pH not less than 5.5 until complete desorption of the cations present in the filtration material,
- passing through the filtration material (4) a basic flow at pH >10 and recirculating it through said material for a time sufficient to saturate it with arsenic,
- passing through the filtration material (4) at least a second quantity of a basic flow to achieve further removal of absorbed arsenic not removed by the first passage,
- rinsing the filtration material with a volume of water equal to its own volume with the addition of an acid such as to maintain the pH of the solution at a value not less than 5.5,
- continuing rinsing by recirculating water until this latter on leaving the filtration material reaches a pH value of about 7.5,
- treating the basic flow leaving the filter (6) in a precipitator (8), initially with ferric chloride and then with calcium hydroxide until arsenic precipitation is complete,
- adding a flocculating agent to remove the calcium hydroxide remaining in suspension,
- feeding the sludge obtained to a decanter (10).</p> |
