| Lanthanum/aluminum-modified zeolite is a new material that is used to remove phosphorus from waste water. For lanthanum/aluminum-modified zeolite has the advantages of high phosphorus removal efficiency, low expense, innocuity, environment friendly, its application prospect is extremely broad. However, use lanthanum/aluminum-modified zeolite to remove phosphorus from waste water has a disadvantage of producing a lot of chemical sludge. And the effective approach of reducing the chemical sludge is to release phosphorus from lanthanum/aluminum-modified zeolite saturated with phosphorus and improve its regenerability. In order to know the best phosphorus release condition of lanthanum/aluminum-modified zeolite saturated with phosphorus, the effect of pH on the release of phosphorus from lanthanum/aluminum-modified zeolite saturated with phosphorus was investigated by adjusting the pH from 2.0 to 13.0 using NaOH and HCl solutions. And the regenerability of lanthanum/aluminum-modified zeolite was researched simultaneously under the best phosphorus release and best phosphorus adsorption conditions. And the result showed that the amount and ratio of phosphorus releasing from lanthanum/aluminum-modified zeolite decreased firstly and then increased when pH changed from 2 to 13. When pH was 2, 12 and 13, the phosphorus release ratio was higher than 76%, and the phosphorus release ratio reached the highest point when the pH was 13 and the highest value was 98.2%. When pH ranged from 3 to 11, the phosphorus release ratio was lower than 30%, and the phosphorus release ratio reached the lowest point when the pH was 6 and the lowest value was 1.7%. So it could be concluded that strong acid and alkali environment was in favor of phosphorus releasing from lanthanum/aluminum-modified zeolite. The test of the regenerability of lanthanum/aluminum-modified zeolite showed that the phosphorus adsorption amount and the regenerability of lanthanum/aluminum-modified zeolite were 2.367 mg·g-1, 2.336 mg·g-1, 2.312 mg·g-1, 2.253 mg·g-1 and 96.7%, 95.5%, 94.5%, 92.1% respectively in the four times of regeneration and adsorption tests. The adsorption ability of lanthanum/aluminum-modified zeolite decreased with the increasing of regeneration time, however, the adsorption ability was still more than 92%, which meant that lanthanum/aluminum-modified zeolite had a good stability and regenerability. |
