Center for Sustainable Technologies, Indian Institute of Science, Bangalore, India.
Center for Sustainable Technologies, Indian Institute of Science, Bangalore, India.
Sci Total Environ. 2023 Jun 15;877:162869. doi: 10.1016/j.scitotenv.2023.162869. Epub 2023 Mar 16.
The over-exploitation and insufficient replenishment of groundwater (GW) have resulted in a pressing need to conserve freshwater and reuse of treated wastewater. To address this issue, the Government of Karnataka launched a large-scale recycling (440 million liters/day) scheme to indirectly recharge GW using secondary treated municipal wastewater (STW) in drought-prone areas of Kolar district in southern India. This recycling employs soil aquifer treatment (SAT) technology, which involves filling surface run-off tanks with STW that intentionally infiltrate and recharge aquifers. This study quantifies the impact of STW recycling on GW recharge rates, levels, and quality in the crystalline aquifers of peninsular India. The study area is characterized by hard rock aquifers with fractured gneiss, granites, schists, and highly fractured weathered rocks. The agricultural impacts of the improved GW table are also quantified by comparing areas receiving STW to those not receiving it, and changes before and after STW recycling were measured. The AMBHAS_1D model was used to estimate the recharge rates and showed a tenfold increase in daily recharge rates, resulting in a significant increase in the GW levels. The results indicate that the surface water in the rejuvenated tanks meets the country's stringent water discharge standards for STW. The GW levels of the studied boreholes increased by 58-73 %, and the GW quality improved significantly, turning hard water into soft water. Land use land cover studies confirmed an increase in the number of water bodies, trees, and cultivated land. The availability of GW significantly improved agricultural productivity (11-42 %), milk productivity (33 %), and fish productivity (341 %). The study's outcomes are expected to serve as a role model for the rest of Indian metro cities and demonstrate the potential of reusing STW to achieve a circular economy and a water-resilient system.
地下水（GW）的过度开采和补给不足导致了迫切需要保护淡水资源和再利用处理后的废水。为了解决这个问题，卡纳塔克邦政府启动了一个大规模的回收（每天 4.4 亿升）计划，在印度南部科拉尔区干旱地区，利用二级处理后的城市废水（STW）间接回灌 GW。该回收利用采用土壤含水层处理（SAT）技术，包括用 STW 填充地表径流罐，这些 STW 会故意渗透并补给含水层。本研究量化了 STW 回收对印度半岛结晶含水层 GW 补给率、水平和质量的影响。研究区以硬岩含水层为特征，含有片麻岩、花岗岩、片岩和高度破碎的风化岩石。通过比较接收 STW 的区域和未接收 STW 的区域，以及测量 STW 回收前后的变化，也量化了 GW 表改善对农业的影响。使用 AMBHAS_1D 模型来估计补给率，结果显示每日补给率增加了十倍，导致 GW 水平显著增加。结果表明，再生罐中的地表水符合该国对 STW 的严格的水排放标准。研究钻孔的 GW 水平增加了 58-73%，GW 质量显著改善，将硬水变成软水。土地利用土地覆盖研究证实了水体、树木和耕地数量的增加。GW 的可用性显著提高了农业生产力（11-42%）、牛奶生产力（33%）和鱼类生产力（341%）。该研究的结果有望成为印度其他大都市的榜样，并展示再利用 STW 以实现循环经济和水弹性系统的潜力。
