重污染感潮河道底泥释放特征及其控制技术研究

Research on the characteristics of sediment release in a heavily polluted tidal river and control technologies

以珠江三角洲城市重污染感潮河道为对象,研究了底泥污染物（重金属、有机物和营养盐）在静态、潮汐作用影响及人工曝气扰动下的释放特征.在此基础上,采用曝气充氧、重金属化学固定、激活底泥土著微生物等联合技术对底泥释放进行控制,研究其控制效果.结果表明：①感潮作用加速了底泥污染物的释放,与静态释放相比,Cu、Zn、Pb、Cr、COD、NH＋4-N和TP的平均释放速率提高了1-4倍,释放量增加了0.3-1.8倍;底泥平均耗氧速率提高了1.28倍.②人工曝气扰动使底泥污染物局部急剧释放,并使泥水界面由弱碱性变成弱酸性;在有氧环境,NH^＋4-N、TP的释放得到有效抑制.③投加石灰调节pH至8-9,上覆水体Cu、Zn、Pb、Cr的去除率达到85%-98%,同时还可去除92%的TP和86%的浊度;在微碱性好氧条件下,Cu、Zn、Pb和Cr的释放量稳定在300μg·L^-1以下.④底泥土著微生物层对水体及底泥污染物有良好的降解作用,通过间歇曝气COD、NH^＋4-N、TP去除率分别可达到85%、92%和71%;但微生物层具有较高的耗氧速率,达到45g·m^-2·d^-1.

The characteristics of sediment release（including heavy metals,organic compounds and inorganic nutrients） in the heavily polluted tidal rivers in the Pearl River delta were investigated under static,tidal and aerated conditions.In addition,the control of sediment release was studied using aeration,immobilization of the heavy metals,and acceleration of biodegradation by the indigenous microorganisms.The experimental results showed that： ① the tidal process sped up the release of contaminants from surface sediment.The average release rates of Cu,Pb,Zn,Cr,COD,NH＋4-N and TP were 1～4 times faster under tidal conditions than in static conditions,and the quantity released increased 0.3～1.8 times.The average oxygen consumption rate was 1.28 times faster in tidal conditions than when static.②Artificial aeration greatly increased the rate of contaminant release,and changed the pH value at the water-sludge surface from alkaline to slightly acidic.However,the release of NH＋4N and TP was effectively restricted in the aerobic environment.③ When the pH was adjusted to 8～9 by addition of lime,the removal rate of Cu,Zn,Pb and Cr could reach up to 85%～95%.And 92% of TP and 86% of turbidity could also be removed.The amount of Cu,Zn,Pb and Cr released under alkaline,oxidizing conditions was less than 300 μg·L-1.④ The contaminants in the water and sediment were thoroughly degraded by the indigenous microorganisms.The removal rate of COD,NH＋4-N and TP could reach up to 85%,92% and 71%,respectively,under intermittent aeration.However,the microorganisms consumed oxygen at the high rate of 45g·m^-2·d^-1.