Inducing mineral precipitation in groundwater by addition of phosphate

Predicting groundwater phosphate levels in coastal multi-aquifers: A geostatistical and data-driven approach

The groundwater (GW) resource plays a central role in securing water supply in the coastal region of Bangladesh and therefore the future sustainability of this valuable resource is crucial for the area. However, there is limited research on the driving factors and prediction of phosphate concentration in groundwater. In this work, geostatistical modeling, self-organizing maps (SOM) and data-driven algorithms were combined to determine the driving factors and predict GW phosphate content in coastal multi-aquifers in southern Bangladesh. The SOM analysis identified three distinct spatial patterns: K+Na+pH, Ca2+Mg2+NO₃-, and HCO₃-SO₄2-PO43-F-. Four data-driven algorithms, including CatBoost, Gradient Boosting Machine (GBM), Long Short-Term Memory (LSTM), and Support Vector Regression (SVR) were used to predict phosphate concentration in GW using 380 samples and 15 prediction parameters. Forecasting accuracy was evaluated using RMSE, R2, RAE, CC, and MAE. Phosphate dissolution and saltwater intrusion, along with phosphorus fertilizers, increase PO43- content in GW. Using input parameters selected by multicollinearity and SOM, the CatBoost model showed exceptional performance in both training (RMSE = 0.002, MAE = 0.001, R2 = 0.999, RAE = 0.057, CC = 1.00) and testing (RMSE = 0.001, MAE = 0.002, R2 = 0.989, RAE = 0.057, CC = 0.998). Na+, K+, and Mg2+ significantly influenced prediction accuracy. The uncertainty study revealed a low standard error for the CatBoost model, indicating robustness and consistency. Semi-variogram models confirmed that the most influential attributes showed weak dependence, suggesting that agricultural runoff increases the heterogeneity of PO43- distribution in GW. These findings are crucial for developing conservation and strategic plans for sustainable utilization of coastal GW resources.

Preparation of novel nano composite materials from biomass waste and their sorptive characteristics for certain radionuclides

The aim of this work is directed to prepare nanoparticles of egg shell hydroxyapatite-humic acid (ESHAP-HA) as a novel composite material. FTIR, EDX, TEM, XRD, and SEM identified it. Sorption characteristic studies on ESHAP-HA at different pH of solutions, shaking time, initial ion concentration and complexing agent were performed at 152,154Eu, 99Mo and 63Ni. The results were demonstrated that selectivity removal of 152,154Eu (~96 %) rather than 99Mo (8.5 %) and 63Ni (26.7 %). The sorption capacity of 152,154Eu(III), 63Ni(II) and 99Mo(VI) are 80.1, 12.5 and 2.3 mg/g, respectively, onto the ESHAP-HA nanoparticles. Application on the eclectic removal of 152,154Eu from mixed radionuclides (152,154Eu, 60Co, and 137Cs) solution has been evaluated. It concluded that the prepared ESHAP-HA composite material is a promising and recommended for separation of radio lanthanides and/or actinides (such as Am) from nuclear liquid waste and/or contaminated aquatic environmental.

Chemical activity relation of phosphorus and nitrogen presence in trace elements incorporation into underground water

Anthropogenic activities can deteriorate the quality of groundwater destined for human use and consumption due to the fact that human activities cause changes in groundwater chemistry. The changes are induced by chemical species coming from industrial waste, which interacts with rocks and minerals. These trigger agents (phosphorus and nitrogen nutrients) which can incorporate trace elements (As, Fe, Mn, Pb, Cd, Ni, Zn). The main objective of the present work was to study the phosphate ions' and nitrogenous species' effects on the incorporation of trace elements into groundwater used for human consumption and to determine the physicochemical processes that participate in the incorporation of trace elements. The physicochemical analysis and elemental analysis by ICP of the groundwater that supplies the study area showed that the phosphorus (P) activity contributes in the incorporation of trace elements into the water. Significant correlations between the activities of P and Fe (0.516), Mn (0.553), Pb (0.756), and As (- 0.747) as well as the correlation of NH₄⁺ with As indicate that the presence of chemical species such as PO₄^3- (2.50-32.20 mg L^-1), NO₃^- (0.89-30.80 mg L^-1), and NH₄⁺ (0.2-12.70 mg L^-1) are triggering agents that favor the dissolution and mobility of As (0.014-0.020 mg L^-1), Fe (0.020-1.14 mg L^-1), Mn (0.007-0.254 mg L^-1), Ni (0.002-0.0141 mg L^-1), Zn (0.009-0.459 mg L^-1), and Pb (0.009-0.0170 mg L^-1), species with adverse health effects because they are considered carcinogenic. Adequate control of the nitrogenous and phosphated material prevents the dissolution and mobility of trace elements into the water.