TREATMENT OF REACTIVE DYE DYEING WASTE WATER CONTAINING SODIUM SILICATE

摘要

PURPOSE:To recover silicic acid from dyeing waste water with high work performance and efficiency by pH-adjusting the waste water from the acidic side after which the resulting silica gel is dehydrated, crushed into fine granules, injected with water, freezed, remelted, dehydrated, and dissolved in alkali. CONSTITUTION:Dyeing waste water contg. sodium silicate is adjusted to pH 5.5- 7.5 from the acidic side, and the resulting silica gel is dehydrated and coarsely crushed into fine granules, which are then freezed at a state where gaps among the granules are filled with water added. This frozen body is melted by heating, and coarsened silicic acid granules are dehydrated and washed. This silicic acid is dissolved in alkali, recovered as sodium silicate, and recycled. The filtration and dehydration rates are very high, and sodium silicate of high concn. and purity can be recovered in a yield of about 100%.