Sediment pollution characteristics, in situ sediment release potential, and in situ inhibition of sediment release were investigated in a drinking water reservoir. Results showed that organic carbon（OC）, total nitro...Sediment pollution characteristics, in situ sediment release potential, and in situ inhibition of sediment release were investigated in a drinking water reservoir. Results showed that organic carbon（OC）, total nitrogen（TN）, and total phosphorus（TP） in sediments increased from the reservoir mouth to the main reservoir. Fraction analysis indicated that nitrogen in ion exchangeable form and Na OH-extractable P（Fe/Al-P） accounted for 43% and 26% of TN and TP in sediments of the main reservoir. The Risk Assessment Code for metal elements showed that Fe and Mn posed high to very high risk. The results of the in situ reactor experiment in the main reservoir showed the same trends as those observed in the natural state of the reservoir in 2011 and 2012; the maximum concentrations of total OC, TN, TP, Fe,and Mn reached 4.42 mg/L, 3.33 mg/L, 0.22 mg/L, 2.56 mg/L, and 0.61 mg/L, respectively. An in situ sediment release inhibition technology, the water-lifting aerator, was utilized in the reservoir. The results of operating the water-lifting aerator indicated that sediment release was successfully inhibited and that OC, TN, TP, Fe, and Mn in surface sediment could be reduced by 13.25%, 15.23%, 14.10%, 5.32%, and 3.94%, respectively.展开更多
Thermal stratification is a common phenomenon in lakes and reservoirs and has a significant influence on water quality dynamics. Heihe Reservoir is a canyon-shaped reservoir in Shaanxi Province with strong thermal str...Thermal stratification is a common phenomenon in lakes and reservoirs and has a significant influence on water quality dynamics. Heihe Reservoir is a canyon-shaped reservoir in Shaanxi Province with strong thermal stratification. Therefore, eight water-lifting aerators （WLAs） were installed in this reservoir, which could overcome thermal stratification and increase oxygenation with gas flows between 20 and 50 m3/hr, and oxygenate the hypolimnion with gas flows less than 20 m3/hr. To examine the destratification efficiency of the WLA system, we used a three- dimensional hydrodynamic module based on MIKE 3 to simulate the thermal structure of Heihe Reservoir and compared the simulations with measured data. Results showed that operation of the WLA system promoted water mixing and effectively oxygenated the hypolimnion. Through the established energy utilization assessment method, the energy utilization efficiency of the WLA system was between 5.36% and 7.30%, indicating the capability of the technique for destratification in such a large reservoir. When the surface water temperature dropped to the theoretical mixed water temperature calculated by the energy utilization assessment method, reducing gas flow could save energy. This would prevent anaerobic conditions from occurring in the bottom water and maintain good water quality in Heihe Reservoir.展开更多
为探析扬水曝气器内部流动特性,本文采用VOF(Volume of Fluid)法对扬水曝气器流场进行数值模拟,通过比对模拟和实验结果验证了模型的可靠性,详细分析了扬水曝气器内部气弹形成和释放过程及其流动特征,讨论了不同曝气速率和气室体积大小...为探析扬水曝气器内部流动特性,本文采用VOF(Volume of Fluid)法对扬水曝气器流场进行数值模拟,通过比对模拟和实验结果验证了模型的可靠性,详细分析了扬水曝气器内部气弹形成和释放过程及其流动特征,讨论了不同曝气速率和气室体积大小对扬水曝气器提水性能的影响.研究结果表明:数值模拟和试验结果间的误差在6%以内,该方法可靠;利用VOF方法有效模拟了气室中气体的聚集、气弹形成及释放过程,并发现气体进入上升筒中所形成的并不是一个整体气弹,气弹后还尾随许多中小气泡,研究加深了对扬水曝气器内部流动特性的认识;出口平均流速随着曝气速率的增大而增大,随着气室体积的减小而增大,并在参数的计算范围内给出了其拟合关系式;其规律与丛海兵给出的结论一致,进一步印证了本文方法在扬水曝气器性能研究中的适用性,为后续扬水曝气器各项参数的优化设计提供了可靠的分析手段,具有较大的工程应用价值.展开更多
Source water reservoirs easily become thermally and dynamically stratified. Internal pollution released from reservoir sediments is the main cause of water quality problems. To mitigate the internal pollution more eff...Source water reservoirs easily become thermally and dynamically stratified. Internal pollution released from reservoir sediments is the main cause of water quality problems. To mitigate the internal pollution more effectively, a new method, which combined chemical stabilization with water lifting aerator （WLA） technology, was proposed and its effciency in inhibiting pollutant release was studied by controlled sediment-water interface experiments. The results showed that this new method can inhibit pollutant release from sediment effectively. The values of mean effciency （E） in different reactors 2#–5# （1# with no agent, 2# 10 mg/L polymeric aluminum chloride （PAC） was added, 3# 20 mg/L PAC was added, 4# 30 mg/L PAC was added, 5# 20 mg/L PAC and 0.2 mg/L palyacrylamide （PAM） were added） for PO43- were 35.0%, 43.9%, 50.4% and 63.6%, respectively. This showed that the higher the PAC concentration was, the better the inhibiting effciency was, and PAM addition strengthened the inhibiting effciency significantly. For Fe2＋, the corresponding values of E for the reactors 2#–5# were 22.9%, 47.2%, 34.3% and 46.2%, respectively. The inhibiting effect of PAC and PAM on Mn release remained positive for a relatively short time, about 10 days, and was not so effective as for PO43- and Fe2＋. The average effciencies in inhibiting the release of UV254 were 35.3%, 25.9%, 35.5%, 38.9% and 39.5% for reactors 2#–5#, respectively. The inhibiting mechanisms of the agents for different pollutants varied among the conditions and should be studied further.展开更多
文摘在扬水曝气条件下,在原位进行了强化生物接触氧化技术改善滦河水源水质的试验研究,分析测定其处理效果,研究了生物填料悬挂于自然水体不同水深、不同水力停留时间下对生物预处理效果的影响.试验结果表明,扬水曝气加原位采用生物接触氧化组合用于水源水质改善是可行的;该技术对水中CODMn、氨氮、叶绿素a、真实色度、TOC、UV254、铁和锰平均的去除率分别可达10.1%、64.1%、42.4%、48.6%、12.5%、9.5%、48.9%和41.9%;生物填料可悬挂在水体0～3 m水深区,停留时间应大于2～3 h.
基金supported by the National Natural Science Foundation of China(No.51478378)
文摘Sediment pollution characteristics, in situ sediment release potential, and in situ inhibition of sediment release were investigated in a drinking water reservoir. Results showed that organic carbon（OC）, total nitrogen（TN）, and total phosphorus（TP） in sediments increased from the reservoir mouth to the main reservoir. Fraction analysis indicated that nitrogen in ion exchangeable form and Na OH-extractable P（Fe/Al-P） accounted for 43% and 26% of TN and TP in sediments of the main reservoir. The Risk Assessment Code for metal elements showed that Fe and Mn posed high to very high risk. The results of the in situ reactor experiment in the main reservoir showed the same trends as those observed in the natural state of the reservoir in 2011 and 2012; the maximum concentrations of total OC, TN, TP, Fe,and Mn reached 4.42 mg/L, 3.33 mg/L, 0.22 mg/L, 2.56 mg/L, and 0.61 mg/L, respectively. An in situ sediment release inhibition technology, the water-lifting aerator, was utilized in the reservoir. The results of operating the water-lifting aerator indicated that sediment release was successfully inhibited and that OC, TN, TP, Fe, and Mn in surface sediment could be reduced by 13.25%, 15.23%, 14.10%, 5.32%, and 3.94%, respectively.
基金supported by the National Natural Science Foundation of China(Nos.51478378 and 50830303)
文摘Thermal stratification is a common phenomenon in lakes and reservoirs and has a significant influence on water quality dynamics. Heihe Reservoir is a canyon-shaped reservoir in Shaanxi Province with strong thermal stratification. Therefore, eight water-lifting aerators （WLAs） were installed in this reservoir, which could overcome thermal stratification and increase oxygenation with gas flows between 20 and 50 m3/hr, and oxygenate the hypolimnion with gas flows less than 20 m3/hr. To examine the destratification efficiency of the WLA system, we used a three- dimensional hydrodynamic module based on MIKE 3 to simulate the thermal structure of Heihe Reservoir and compared the simulations with measured data. Results showed that operation of the WLA system promoted water mixing and effectively oxygenated the hypolimnion. Through the established energy utilization assessment method, the energy utilization efficiency of the WLA system was between 5.36% and 7.30%, indicating the capability of the technique for destratification in such a large reservoir. When the surface water temperature dropped to the theoretical mixed water temperature calculated by the energy utilization assessment method, reducing gas flow could save energy. This would prevent anaerobic conditions from occurring in the bottom water and maintain good water quality in Heihe Reservoir.
文摘为探析扬水曝气器内部流动特性,本文采用VOF(Volume of Fluid)法对扬水曝气器流场进行数值模拟,通过比对模拟和实验结果验证了模型的可靠性,详细分析了扬水曝气器内部气弹形成和释放过程及其流动特征,讨论了不同曝气速率和气室体积大小对扬水曝气器提水性能的影响.研究结果表明:数值模拟和试验结果间的误差在6%以内,该方法可靠;利用VOF方法有效模拟了气室中气体的聚集、气弹形成及释放过程,并发现气体进入上升筒中所形成的并不是一个整体气弹,气弹后还尾随许多中小气泡,研究加深了对扬水曝气器内部流动特性的认识;出口平均流速随着曝气速率的增大而增大,随着气室体积的减小而增大,并在参数的计算范围内给出了其拟合关系式;其规律与丛海兵给出的结论一致,进一步印证了本文方法在扬水曝气器性能研究中的适用性,为后续扬水曝气器各项参数的优化设计提供了可靠的分析手段,具有较大的工程应用价值.
基金supported by the Major Science and Technology Program for Water Pollution Control and Treatment (No. 2009ZX07424-006)the National Natural Science Foundation of China (No. 50830303)the Program for Changjiang Scholars and Innovative Research Team in University of MOE of China (PCSIRT) (No.IRT0853)
文摘Source water reservoirs easily become thermally and dynamically stratified. Internal pollution released from reservoir sediments is the main cause of water quality problems. To mitigate the internal pollution more effectively, a new method, which combined chemical stabilization with water lifting aerator （WLA） technology, was proposed and its effciency in inhibiting pollutant release was studied by controlled sediment-water interface experiments. The results showed that this new method can inhibit pollutant release from sediment effectively. The values of mean effciency （E） in different reactors 2#–5# （1# with no agent, 2# 10 mg/L polymeric aluminum chloride （PAC） was added, 3# 20 mg/L PAC was added, 4# 30 mg/L PAC was added, 5# 20 mg/L PAC and 0.2 mg/L palyacrylamide （PAM） were added） for PO43- were 35.0%, 43.9%, 50.4% and 63.6%, respectively. This showed that the higher the PAC concentration was, the better the inhibiting effciency was, and PAM addition strengthened the inhibiting effciency significantly. For Fe2＋, the corresponding values of E for the reactors 2#–5# were 22.9%, 47.2%, 34.3% and 46.2%, respectively. The inhibiting effect of PAC and PAM on Mn release remained positive for a relatively short time, about 10 days, and was not so effective as for PO43- and Fe2＋. The average effciencies in inhibiting the release of UV254 were 35.3%, 25.9%, 35.5%, 38.9% and 39.5% for reactors 2#–5#, respectively. The inhibiting mechanisms of the agents for different pollutants varied among the conditions and should be studied further.
