微曝气垂直流湿地中4种基质的充氧性能研究

Oxygen Transfer Efficiency of Four Kinds Substrates Applied in Artificial Aeration Vertical-flow Wetland

通过模型曝气实验研究了公分石、火山石、500级陶粒、高强级陶粒4种基质和空白水柱分别在0.19、0.38、0.76m3.(m2.h)-13种曝气强度下的充氧性能.结果表明,在相同条件下,曝气强度越大,氧转移速率常数KLa越大,填充了基质的模型的氧转移速率常数比空白提高了5～7.8倍;在0.19m3.(m2.h)-1曝气强度下,500级陶粒和高强级陶粒的氧利用率最高,分别为14.39%和14.21%,火山石和公分石的氧利用率分别为13.11%和11.68%;随着曝气强度的提高,公分石的氧利用率明显高于其它基质,在0.38m3.(m2.h)-1曝气强度下达到最大值14.04%,比该状况下空白模型的氧利用率高出3倍,火山石的氧利用率持续下降,在0.76m3.(m2.h)-1曝气强度下,氧利用率为7.67%,500级陶粒和高强级陶粒的氧利用率较为稳定,维持在10%左右.

In subsurface flow constructed wetlands, artificial aeration plays an important role in enhancing the ability of pollutant removal. Oxygenation capacity of four substrates, limestone, vesuvianite, 500 grade ceramisite and high-strength ceramisite, are tested under three kinds of gas volume [0.19, 0.38, 0.76 m^3·（m^2·h）^-1] in artificial aeration vertical-flow wetland. When the gas volume is 0.19 m^3·（m^2·h）^-1 , the results demonstrate that the oxygen utilization of 500 grade ceramisite and high-strength ceramisite are highest as 14.39 % and 14.21%, and the oxygen utilization of limestone and vesuvianite are 11.68 % and 13.11% respectively. With the increase of aeration intensity, oxygen transfer efficiency parameter KLa rises accordingly. However, the oxygen utilization of vesuvianite and two other kinds of ceramisite decreases with the increase of aeration intensity. The oxygen utilization of vesuvianite, 500 grad ceramisite and high-strength ceramisite are lower as 7.67%, 10.46% and 10.77 % respectively when the aeration intensity is 0.76 m^3·（m^2·h）^-1 . On the contrary, the oxygen utilization of limestone get its maximum value of 14.04 % as the aeration intensity is 0. 38 m^3·（m^2·h）^-1.