覆盖法控制城市河涌底泥磷释放研究

Suppressing phosphate liberation from urban river sediment using capping method

建立了一套包含有城市河涌底泥、覆盖材料及上覆水的小试装置,采用粉煤灰、水泥、沸石、河砂、玻璃珠等不同物质作为覆盖材料,在厌氧条件下,覆盖材料对城市河涌底泥磷释放的控制效果进行了研究.结果表明,在培养温度为25℃,覆盖材料用量为6.0kg·m-2时,玻璃珠、河砂、沸石、粉煤灰、水泥对PO3-4释放的抑制率分别为40.0%、46.7%、60.0%、75.6%、88.9%;覆盖材料对PO3-4的抑制作用可归结为覆盖材料的覆盖效应、化学效应和吸附效应;覆盖材料对PO3-4释放的抑制率均随着温度的升高而降低;覆盖材料用量对PO3-4抑制率影响较大,对于水泥、粉煤灰、沸石、河砂,要达到约50%的PO3-4释放抑制率,其用量分别为2.0、2.0、6.0、10.0kg·m-2,选用粉煤灰作为覆盖材料较合适;从重金属毒理学方面讲,覆盖材料不会对底泥及区域土壤造成影响.

The effect of suppression on phosphate liberation from urban river sediment by using fly ash, ordinary Portland cement （OPC）, zeolite, river sand and glass bead was investigated by small scale experiment. A system including sediment, water and several kinds of capping materials was designed to clarify the suppression of phosphate liberation from sediment under the anaerobic condition. When the amounts of the capping materials used was 6.0 kg·m^-2, the suppression efficiency of glass bead was 40.0% , and that of river sand, zeolite, fly ash and OPC was 46.7% , 60.0% , 75.6% and 88.9% , respectively, at 25 ℃ The suppression of phosphate was mainly caused by the covering effect, chemical effect and adsorption effect of the capping materials. The suppression efficiency was depended on the temperature and the amounts of the material used, and about 50% of liberated phosphate was suppressed by fly ash of 2.0 kg· m ^- 2, OPC of 2.0 kg· m^ - 2, zeolite of 6.0 kg· m ^- 2, and river sand of 10. 0 kg· m^- 2, respectively. The fly ash was suitable for capping use, and the capping materials had negligible toxic effect on sediment and soil.