曝气深度对河道底泥特性及水质的影响

Effect of different aeration depth on river sediment characteristics and water quality

采用室内模拟实验方法对受污河道底泥和上覆水进行研究,对比分析静置状态X0和不同曝气深度条件下(分别为水体曝气泥水界面上方10 cm,底泥曝气下方5和15 cm处,依次记为X+10、X-5和X-15)河道底泥特性及水质的影响情况。结果表明:底泥曝气较水体曝气而言,能促进水体DO更快恢复;停止曝气,DO浓度也会维持在较高的状态,有利于有机物和氨氮的进一步去除。在相同曝气量下,底泥曝气比水体曝气能更好地去除底泥中污染物,并减少再次释放,且底泥曝气深度越深,处理效果越好,至实验结束时,X-15组上覆水中COD、NH_4^+-N、TN及TP浓度分别为16.25、3.03、13.39及0.09 mg/L,去除率分别为69.73%、78.36%、45.98%及84.21%;停止曝气后,经曝气处理的底泥对磷的吸附容量显著增加,并且不会再向上覆水中释放污染物,避免引起水体的二次污染。

Indoor simulation tests were used to study aeration treatments for polluted river sediments and overlying water. The river sediment characteristics and water quality were evaluated under static state conditions（ X_0） and at different aeration depth,where the heights relative to the water-sediment interface in the aeration treatments were set to 10 cm（ X_（＋10））,- 5 cm（ X_（-5））,and- 15 cm（ X_（-15））. The results showed that sediment aeration can achieve greater restoration levels of dissolved oxygen（ DO） in water bodies and maintain higher DO levels after stopping aeration than techniques that rely solely on water aeration,which will be beneficial for the further removal of organic matter and ammonia nitrogen. Sediment aeration may also suppress the release of pollutants from the sediments to the overlying water. In this study,greater sediment aeration depth were associated with better treatment efficiencies. At the end of the tests,the chemical oxygen demand（ COD）（ where refers to the dichromate method）,NH4^＋-N,total nitrogen（ TN）,and total phosphorous（ TP） concentrations of the X- 15 group were 16. 25,3. 03,13. 39 and 0. 09 mg / L,and the corresponding removal rates were 69. 73%,78. 36%,45. 98%,and 84. 21%,respectively. After stopping aeration,the accumulative adsorption capacity for phosphorus in sediment subjected to aeration treatments increased significantly,and pollutant release was restrained effectively. Therefore,these water bodies were protected from the effects of secondary pollution.