Over recent years, waters in and around Fiji has increasingly succumbed to a reasonable level of contamination. Water quality is defined with set of standards that clearly state the parameters of different properties in water. These standards are different at various geographic locations. The specific quantitative values of these parameters for the Fiji Islands are established by the Fiji National Drinking Water Quality Standards (FNDWQS). Fiji is geographically located in the vast Pacific Ocean, and requires a data collection framework for different water parameters to monitor water quality. The GIS framework system can effectively solve this continuously in real-time. With the end goal being to quantify different parameters; four (04) key performance indicators (KPI) are identified: Temperature, potential of hydrogen (pH), Oxidation Reduction Potential (ORP), and Conductivity. This paper presents a Smart Water Quality Monitoring System (SWQMS) which has been developed and deployed in five (05) Fijian locations (nodes) for the aforementioned KPIs measurement. The SWQMS interfaced with GIS and were powered using solar based Renewable Energy Source (REs). Finally, obtained data were tested and analyzed using statistical methods and verified comparing with the FNDWQS. The findings demonstrated that the system is capable of delivering an accurate and consistent measurement of water quality in real-time. Hence SWQMS could be a smart choice for various Pacific Island Countries (PICs) to use to monitor the water quality and in turn develop sustainable cities and societies.

Environmental pollution caused by hexavalent chromium [Cr(IV)] is a critical global concern due to its carcinogenic and acute toxicity. This study describes the synthesis of crosslinked polyethylene imine (PEI) and polyaniline (salt and base forms) and their effectiveness at removing dichromate ion (Cr₂O₇²⁻) from aqueous solutions. The synthetized polymer adsorbents were comprehensively characterized using IR, TGA, and SEM-EDX methods. The adsorption processes were monitored via colorimetry and UV–Vis spectroscopy using the 1,5-diphenylcarbazide method under acidic conditions. Kinetic modeling revealed that the adsorption data fitted well to the pseudo-second-order model, confirming a chemisorption-controlled process. Equilibrium data followed the Langmuir isotherm at room temperature, predicting maximum adsorption capacities of 161 mg/g for PEI and exceeding 285 mg/g for the PANI salt. Thermodynamic parameters (ΔG°, ΔH°, and ΔS°) were all negative, confirming the spontaneous and exothermic nature of the adsorption process. In selective competitive studies, the PANI salt demonstrated exceptional robustness, maintaining a Cr(VI) removal efficiency of 93% to 99% in the concurrent presence of KH₂PO₄, NaNO₃, and CuSO₄ interferents, which is highly comparable to the control. Conversely, the removal efficiency of PEI was sensitive to the matrix, dropping to 52–53% in the presence of NaNO₃ and CuSO₄ while remaining unaffected (65%) by KH₂PO₄. Furthermore, regeneration studies using 5% HNO₃ demonstrated stable reusability, with both polymers maintaining high adsorption efficiencies (88–99%) over four consecutive cycles. These findings highlight the significant potential of these accessible polymeric materials for functional integration into real-world industrial wastewater treatment facilities.