MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, Institute of Geotechnical Engineering, Zhejiang University, Yuhangtang Road 866#, Hangzhou, 310058, China.
Environ Sci Pollut Res Int. 2021 Aug;28(30):41283-41295. doi: 10.1007/s11356-021-13414-7. Epub 2021 Mar 29.
The pumping performance of the traditional vertical well is often poor in municipal solid waste (MSW) landfills due to the blocking effect of landfill gas on leachate migration. To improve the pumping performance, a vacuum vertical well was designed and then installed at the Tianziling landfill. When the leachate was drawn out through submersible pump, the landfill gas was simultaneously extracted through vacuum pump to form vacuum pressure in the well. The vacuum pressure could increase the hydraulic gradient of leachate flow as well as the relative liquid permeability of MSW. Pumping tests were carried out to explore the effectiveness of the vacuum pressure on improving the pumping performance of vertical well. When the vacuum pressure increased from 0 kPa to - 30 kPa, the steady leachate pumping rate increased from 1.58 to 2.34 m/h, and the steady leachate level drawdown increased from 5.9 to 10.3 m at the distance of 5 m. The vacuum pressure mainly affected the leachate level drawdown within the distance of 15-20 m. When the vacuum pressure in the pumping well was - 30 kPa, it attenuated to - 14.7 kPa and - 6.6 kPa at the distance of 5 m and 10 m, respectively. The influence radius of vacuum pressure was about 15 m. Numerical modeling indicates that the leachate pumping rate and drawdown will decrease with the increase in decreasing rate of hydraulic conductivity with depth, degree of heterogeneity, and anisotropy of hydraulic conductivity of waste. The experimental and numerical results demonstrate the effectiveness of vacuum pressure and provide working parameters for the application of the vacuum wells in MSW landfills.
传统的垂直井在城市固体废物（MSW）垃圾填埋场中的泵送性能通常较差，因为填埋气会对渗滤液迁移产生阻碍作用。为了提高泵送性能，设计并在天子岭垃圾填埋场安装了真空垂直井。当潜水泵抽出渗滤液时，真空泵同时抽取填埋气，在井内形成真空压力。真空压力可以增加渗滤液流动的水力梯度和 MSW 的相对液体渗透率。进行了泵送测试，以探讨真空压力对提高垂直井泵送性能的效果。当真空压力从 0 kPa 增加到-30 kPa 时，稳定的渗滤液抽提速率从 1.58 增加到 2.34 m/h，稳定的渗滤液水位下降从 5.9 增加到 10.3 m，距离为 5 m。真空压力主要影响距离为 15-20 m 的渗滤液水位下降。当抽水井中的真空压力为-30 kPa 时，在距离 5 m 和 10 m 处分别衰减至-14.7 kPa 和-6.6 kPa。真空压力的影响半径约为 15 m。数值模拟表明，随着水力传导率随深度的降低率、非均质性程度和水力传导率各向异性的增加，渗滤液抽提速率和水位下降都会减小。实验和数值结果证明了真空压力的有效性，并为真空井在 MSW 垃圾填埋场中的应用提供了工作参数。
