Groundwater is increasingly being used to help meet the Sustainable Development Goals (SDGs) 2 and 6 in many parts of the world, including Ghana. Against this background, hydrogeochemical and multivariate statistical studies were conducted to determine the physicochemical characteristics and suitability of groundwater in some agrarian communities in the Upper East Region of Ghana for drinking and irrigational farming. Additional analyses were also performed to identify potential health risks associated with the groundwater use and to better understand the hydrogeochemical processes controlling groundwater evolution for its effective management. The results showed that the groundwater is typically fresh; moderate to very hard in character; undersaturated with calcite, dolomite, halite, and gypsum; and supersaturated with quartz and amorphous silica. The physicochemical characteristics of the groundwater are controlled by both anthropogenic and natural activities/processes, such as fertilizer application, irrigation return flows, rock weathering, and forward/reverse cation exchange. The total dissolved solids (TDS) (165–524 mg/L), electrical conductivity (EC) (275–873 μS/cm), sodium percentage (Na%; 9.05–17.74%), magnesium ratios (MR) (29.25–53.3%), permeability index (PI) (36.6–74.6%), and sodium adsorption ratio (SAR) (0.20–0.51) point to the possibility of using the groundwater for irrigation, however, with some salinity control. The water quality and health risk analysis also revealed that the groundwater can be used for drinking; however, the high concentrations of fluoride, which can cause noncarcinogenic health issues such as dental and skeletal fluorosis in both adults and children, must be reduced to the WHO required level of 1.5 mg/L.

This study investigates the potential of natural Brown Coal (BC) as a sustainable, cost-effective adsorbent for the removal of manganese (Mn²⁺) from contaminated groundwater. A series of batch adsorption experiments was conducted to assess the influence of key operational parameters—such as solution pH, initial Mn²⁺ concentration, BC dosage, temperature, and the presence of competing ions—on Mn²⁺ removal efficiency. The environmental compatibility and regeneration potential of BC were also evaluated to determine its practical viability for repeated use. To better understand the adsorption behaviour, equilibrium and kinetic data were analysed using established isotherm and kinetic models, while thermodynamic parameters were computed to assess the spontaneity and thermal characteristics of the adsorption process. Furthermore, geochemical modelling and comprehensive BC characterization—including surface morphology, mineralogical and elemental composition, and functional group analysis—were performed to elucidate Mn²⁺ speciation under varying environmental conditions and to uncover the underlying adsorption mechanisms. Results showed that Mn²⁺ removal efficiency increased with higher pH, temperature, and BC dosage, but declined at elevated initial Mn²⁺ concentrations due to active site saturation. The process was spontaneous and endothermic, with the Langmuir isotherm model (R² = 0.994) and pseudo-second-order kinetic model (R² = 0.996) providing the best fit to experimental data. Mechanistic analysis indicated that chemisorption, primarily through ion exchange and inner-sphere complexation, was the dominant mode of Mn²⁺ uptake. The presence of competing cations, especially Fe³⁺ and Cu²⁺, significantly hindered Mn²⁺ removal due to preferential binding. Importantly, BC exhibited strong reusability, maintaining over 80% removal efficiency across four adsorption–desorption cycles without evidence of secondary pollutants. These findings demonstrate the potential of natural BC as an efficient, reusable, and environmentally benign material for treating manganese-contaminated groundwater.