几种覆盖材料抑制湖泊污染底泥氮释放的试验研究

建立了一套模拟湖泊小试装置,分别采用含黏土的沙子、清洁黄土和土工布3种材料覆盖湖泊污染底泥,抑制底泥中的氮释放。试验控制在恒温25℃厌氧条件下进行,经过75d静置试验,结果表明:含黏土的沙子和清洁黄土均能有效抑制污染底泥的氮释放,而单独使用土工布的效果不佳;覆盖材料的覆盖厚度越厚,抑制污染底泥氮释放的效果越好;覆盖厚度为5cm、15cm和30cm的沙子对污染底泥氮释放的抑制率分别为74.9%、94.0%和96.8%,覆盖厚度为5cm、15cm和30cm的黄土对污染底泥氮释放的抑制率分别为77.2%、95.5%和98.8%,可见黄土的效果更优;从工程成本考虑,采用15cm覆盖厚度即可。

Experimental Study on Inhibiting Nitrogen Release from Contaminated Sediments by Several Capping Materials

A lab-scale simulation lake was built to study how to control nitrogen release from contaminated sediments.Sand-containing clay,clean loess and geotextile were placed on top of contaminated sediments respectively to inhibit nitrogen release.The temperature of lab-scale equipment was kept at 25℃.The contaminated sediments were under anaerobic conditions.The experiment lasted for 75 days.The results show that sand-containing clay and clean loess can greatly inhibit nitrogen release from contaminated sediments;however,the effects of geotextile are not good.The inhibition effects increase with the thickness of the cover.The inhibition ratios of nitrogen release from contaminated sediments are 74.9%(5 cm),94.0%(15 cm) and 96.8%(30 cm) for sand,and 77.2%(5 cm),95.5%(15 cm) and 98.8%(30 cm) for clean loess respectively.Therefore,the clean loess is the best of all three.Considering engineering cost control,the optimal thickness of loess layers is 5~15 cm.