Electro-galvanic alkalization and treatment of rainwater to obtain drinking water

ABSTRACT

Rainwater Electro-Galvanic Alkalization (EGA) was performed using copper and magnesium (1:1) electrode. Efficiently removal of pollutants without external energy consumption was carried out, in addition essential ions were dosed for alkalization of rainwater. The optimal system conditions were obtained using response surface methodology (RSM) by considering the following operating variables: flow rate and concentration of the supporting electrolyte (NaCl and CaCl₂). Furthermore, the maximum efficiency of nitrate, ammoniacal nitrogen, colour, and turbidity removal was evaluated. The results showed that the response variables were mainly sensitive to the type of supporting electrolyte used and the flow rate. Under experimental conditions of 0.009 M (NaCl) and 20 mL min⁻¹, the removal rate was 74.19%, 72.49%, and 81.43% for nitrates, colour, and turbidity, respectively, and the lowest concentration of ammoniacal nitrogen ($0.99\mathrm{mg}{\mathrm{L}}^{-1}$) was obtained. The kinetic models for nitrate and colour were fitted to zero-order models with $k=0.33\mathrm{mg}{\mathrm{L}}^{-1}\mathrm{mi}{\mathrm{n}}^{-1}$ and $k=0.933\mathrm{Pt}-\mathrm{Co}$, respectively. In addition, turbidity was fitted to a first-order model $(k=0.1661\mathrm{mi}{\mathrm{n}}^{-1})$, and ammoniacal nitrogen was fitted to a second-order model $(k=0.0217\mathrm{L}\mathrm{m}{\mathrm{g}}^{-1}\mathrm{mi}{\mathrm{n}}^{-1})$. The concentration increases of minerals such as Ca and Mg, which rises the rainwater alkalinity after treatment (pH shift from 6.1 to 8.91), was determined by inductively coupled plasma (ICP) analysis.

GRAPHICAL ABSTRACT

KEYWORDS:

• Rainwater
• water quality
• galvanic treatment
• water consumption
• Mg/Cu electrodes

Acknowledgments

The authors thank the Autonomous University of the State of Mexico for financial support granted through the 6738/2022 CIB UAEMex research project and the National Council of Science and Technology (CONAHCYT) for the scholarship (930180) for Cristina Morales Figueroa. We appreciate the support of the Geochemistry Environmental Department, Geosciences Center, UNAM, Campus Juriquilla, for ICP determination.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data supporting of this study are available within the supplementary material.

Additional information

Funding

This work was supported by Universidad Autónoma del Estado de México [grant number: 6738/2022 CIB]; CONAHCYT [grant number: 930180].