CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad 500007, India.
Department of Environmental Science, Osmania University, Hyderabad 500007, India.
Water Res. 2019 Jan 1;148:176-187. doi: 10.1016/j.watres.2018.10.040. Epub 2018 Oct 17.
Natural wetlands are green infrastructure systems that are energy-efficient for wastewater treatment and can be found in diverse geo-environmental settings around the world. Their structure and functions, which defines the treatment efficiencies are highly varied. Wetlands over shallow bedrock and geological lineaments (weak zones) have been known to contribute to groundwater contamination. However, not many studies have been performed to understand the structure in different geological settings to identify the efficiency determining factors. Therefore, it is important to investigate the geological suitability of the natural wetlands. We examined wastewater fed natural wetlands in diverse geological settings aiming at studying the depth, geo-stability, bio-chemical interactions, and hydrogeological attributes that improve the wastewater quality, within the Musi River basin, India. The integrated geophysical scans encompassing electrical resistivity tomography (ERT), hydrogeological test, bathymetric study and hydro-chemical analysis were carried out to explore the physical structure and hydro-dynamic processes in the wetlands. ERT investigations showed that, the depth to bedrock up to 20-25 m devoid of geo-fractures (lineaments) indicated the effective depth of saturated zone as a passable scope for potential bio-chemical interactions, implying the proportionality of the deep seated (deep bedrock) wetland to the pollutant removal efficiency. The lower order of electrical resistivity range 10-35 Ωm and hydraulic conductivity 2.938 md acquired for saturated weathered zone were found catalyzing the bioremediation, sedimentation, adsorption, redox reactions and ion exchange processes. It caused the deep seated wetland removing nitrate 194.34 kgd (97.18%); sulphate 333.75 kgd (77.70%); phosphate 9.66 kgd (82.53%); microbes 99.99%, BOD 80%, and COD 80% load with discharge 1408 md of treated wastewater. Further, the strategies for designating the natural wetlands as wastewater treatment systems are also discussed in this paper.
自然湿地是一种节能型的污水处理绿色基础设施系统，在世界各地的各种地理环境中都有存在。其结构和功能决定了处理效率，具有高度的多样性。人们已经知道，在浅层基岩和地质线性体（薄弱带）上的湿地会导致地下水污染。然而，目前还没有很多研究来了解不同地质环境中的结构，以确定决定效率的因素。因此，研究自然湿地的地质适宜性非常重要。我们研究了印度默西河盆地不同地质背景下的污水自然湿地，旨在研究改善污水水质的深度、地质稳定性、生物化学相互作用和水文地质特性。我们进行了综合地球物理扫描，包括电阻率层析成像（ERT）、水文地质测试、水深测量和水化学分析，以探索湿地的物理结构和水动力过程。ERT 调查显示，基岩深度达 20-25 米，没有地质断裂（线性体），这表明饱和带的有效深度是潜在生物化学相互作用的可行范围，这意味着深部（深基岩）湿地与污染物去除效率成正比。获得的饱和风化带的低电阻率范围 10-35 Ωm 和水力传导率 2.938 md 促进了生物修复、沉淀、吸附、氧化还原反应和离子交换过程。这使得深部湿地去除硝酸盐 194.34 kgd（97.18%）；硫酸盐 333.75 kgd（77.70%）；磷酸盐 9.66 kgd（82.53%）；微生物 99.99%，BOD80%，COD80%，处理后的废水排放量为 1408 md。此外，本文还讨论了将自然湿地指定为污水处理系统的策略。
