Most water systems that support ecosystems and feed humans are depleted or stressed. Aquifer characteristics, topography, subsurface activities, climate, and geochemical processes regulate groundwater availability, a reliable source of fresh water. Globally, agriculture, industries, and the domestic sector are the three major sectors that consume vast quantities of freshwater resources. Further anthropogenic activities, such as soil leaching, acid rain, fertilizer, pesticides, mining, and other industrial activities, resulted in the release of organic and inorganic pollutants that affected global water resources. In India, groundwater is used in huge quantities, resulting in groundwater depletion of 1 to 2 m a year. Low-income countries face many issues related to water pollution, and the availability of safe water is minimal. In 2019, deaths due to unsafe sanitation accounted for 2.2% of the total global deaths, amounting to 1.2 million people’s deaths. India recorded 6.6% of deaths due to unsafe sanitation in 2019. India and China accounted for around 90.41% and 60.4% of the groundwater utilization for agricultural purposes, respectively. In 2020, China and India utilized vast quantities of nutrients (nitrate and phosphate) for crop growth to enhance crop yield, resulting in the highest nitrate and phosphate concentrations in groundwater. Remediating contaminants from different sources requires knowledge of their concentration, behavior, cycling, and degradation pathways. According to safety guidelines, limiting and optimizing crop organic and inorganic fertilizer, pesticide waste disposal, and empty container disposal can reduce groundwater contamination. The present study summarized groundwater utilization in various sectors, potential sources of groundwater contamination impacts on human health and the environment, preventive measures, and mitigation methods to overcome groundwater pollution.

The present study demonstrates the removal of lead ion from aqueous solution by the adsorption process using Manilkara zapota tree wood-based activated carbon (MZTWAC) as an adsorbent. The MZTWAC was characterized using a scanning electron microscope and Fourier transform infrared spectroscopy. XRD analysis was carried on MZTWAC. Batch adsorption studies were designed and performed to evaluate the adsorption property of MZTWAC for the removal of lead from an aqueous solution based on the central composite design with response surface methodology. The experiments were focused on the individual and combined effects of process parameters, namely, lead concentration, pH and adsorbent dose on the uptake of lead from aqueous solution. A quadratic polynomial equation was established between the adsorption capacity of the activated carbon and the parameters influencing the adsorption with a coefficient of determination R² = 0.9792. The analysis of variance gauged the significance of process parameters and the optimization of process variables was attained by desirability function. There was a noticeable indication of the strong connotation of lead adsorption with Langmuir (R²= 0.9911) and Freundlich (R²= 0.8368) isotherm models. The D-R isotherm model indicated that physisorption occurred in the adsorption of lead by MZTWAC. The pseudo-second-order adsorption kinetic model (R²= 0.9973) perfectly fitted into the present study. GRAPHICAL ABSTRACT