Center for Sustainable Technologies, Indian Institute of Science, Bengaluru, India.
Center for Sustainable Technologies, Indian Institute of Science, Bengaluru, India.
Environ Pollut. 2023 Nov 15;337:122516. doi: 10.1016/j.envpol.2023.122516. Epub 2023 Sep 8.
The utilization of direct wastewater for irrigation poses many environmental problems such as soil quality deterioration due to the accumulation of salts, heavy metals, micro-pollutants, and health risks due to undesirable microorganisms. This hampers its agricultural reuse in arid and semi-arid regions. To address these concerns, the present study introduces a recent approach that involves using indirectly recharged groundwater (GW) with secondary treated municipal wastewater (STW) for irrigation through a Soil Aquifer Treatment-based system (SAT). This method aims to mitigate freshwater scarcity in semi-arid regions. The study assessed GW levels, physicochemical properties, and microbial diversity of GW, and soil in both impacted (receiving recycled water) and non-impacted (not receiving recycled water) areas, before recycling (2015-2018) and after recycling (2019-2022) period of the project. The results indicated a significant increase of 68-70% in GW levels of the studied boreholes in the impacted areas. Additionally, the quality of indirectly recharged GW in the impacted areas improved notably in terms of electrical conductivity (EC), hardness, total dissolved solids (TDS), sodium adsorption ratio (SAR), along with certain cations and anions (hard water to soft water). No significant difference was observed in soil properties and microbial diversity of the impacted areas, except for EC and SAR, which were reduced by 50% and 39%, respectively, after the project commenced. The study also monitored specific microbial species, including total coliforms, Escherichia coli (as indicator organisms), Shigella, and Klebsiella in some of the harvested crops (beetroot, tomato, and spinach). However, none of the analysed crops exhibited the presence of the studied microorganisms. Overall, the study concludes that indirectly recharged GW using STW is a better sustainable and safe irrigation alternative compared to direct wastewater use or extracted hard GW from deep aquifers.
直接利用污水进行灌溉会带来许多环境问题，例如土壤质量因盐分、重金属、微污染物的积累而恶化，以及因不良微生物而带来的健康风险。这阻碍了污水在干旱和半干旱地区的农业再利用。为了解决这些问题，本研究提出了一种新方法，即在半干旱地区利用间接补给的地下水（GW）与二级处理后的城市污水（STW）通过基于土壤-含水层处理（SAT）的系统进行灌溉。该方法旨在缓解半干旱地区的淡水短缺问题。该研究评估了 GW 水平、GW 和土壤的理化性质和微生物多样性，包括受影响（接收再生水）和不受影响（不接收再生水）地区，在项目的回收前（2015-2018 年）和回收后（2019-2022 年）。结果表明，受影响地区研究钻孔的 GW 水平显著增加了 68-70%。此外，受影响地区间接补给 GW 的水质在电导率（EC）、硬度、总溶解固体（TDS）、钠吸附比（SAR）以及某些阳离子和阴离子（硬水变软水）方面显著改善。受影响地区的土壤性质和微生物多样性没有明显差异，除了 EC 和 SAR，项目开始后分别降低了 50%和 39%。该研究还监测了部分回收作物（甜菜、番茄和菠菜）中特定微生物的种类，包括总大肠菌群、大肠杆菌（作为指示生物）、志贺氏菌和克雷伯氏菌。然而，在分析的作物中没有发现研究的微生物。总的来说，该研究得出结论，与直接利用污水或从深层含水层抽取硬 GW 相比，利用 STW 间接补给 GW 是一种更好的可持续和安全的灌溉替代方案。
