Electrochemical nutrient removal from natural wastewater sources and its impact on water quality

László Kékedy-Nagy; Leah English; Zahra Anari; Mojtaba Abolhassani; Bruno G Pollet; Jennie Popp; Lauren F Greenlee

doi:10.1016/j.watres.2021.118001

Electrochemical nutrient removal from natural wastewater sources and its impact on water quality

Water Res. 2022 Feb 15:210:118001. doi: 10.1016/j.watres.2021.118001. Epub 2021 Dec 23.

Authors

László Kékedy-Nagy¹, Leah English², Zahra Anari³, Mojtaba Abolhassani⁴, Bruno G Pollet⁵, Jennie Popp², Lauren F Greenlee⁶

Affiliations

¹ Ralph E. Martin Department of Chemical Engineering, University of Arkansas, 3202 Bell Engineering Center, Fayetteville AR 72701, United States; Department of Electrical and Computer Engineering, Concordia University, Center of Structural and Functional Genomics, 7141 Sherbrooke St. West, Montreal H4B 1R6, Canada.
² Department of Agricultural Economics and Agribusiness, University of Arkansas, 217 Agriculture Building, Fayetteville, AR 72701, United States.
³ Ralph E. Martin Department of Chemical Engineering, University of Arkansas, 3202 Bell Engineering Center, Fayetteville AR 72701, United States; Department of Chemical Engineering, Pennsylvania State University, 121 Chemical and Biomedical Engineering Building, University Park, PA 16802 United States.
⁴ Ralph E. Martin Department of Chemical Engineering, University of Arkansas, 3202 Bell Engineering Center, Fayetteville AR 72701, United States.
⁵ Hydrogen Energy and Sonochemistry research group, Department of Energy and Process Engineering, Faculty of Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway; Green Hydrogen Lab, Hydrogen Research Institute, Université du Québec à Trois-Rivières, 3351 Boulevard des Forges, Trois-Rivières, Québec G9A 5H7, Canada.
⁶ Ralph E. Martin Department of Chemical Engineering, University of Arkansas, 3202 Bell Engineering Center, Fayetteville AR 72701, United States; Department of Chemical Engineering, Pennsylvania State University, 121 Chemical and Biomedical Engineering Building, University Park, PA 16802 United States. Electronic address: greenlee@psu.edu.

PMID: 34974342
DOI: 10.1016/j.watres.2021.118001

Abstract

In this study, a suite of natural wastewater sources is tested to understand the effects of wastewater composition and source on electrochemically driven nitrogen and phosphorus nutrient removal. Kinetics, electrode behavior, and removal efficiency were evaluated during electrochemical precipitation, whereby a sacrificial magnesium (Mg) anode was used to drive precipitation of ammonium and phosphate. The electrochemical reactor demonstrated fast kinetics in the natural wastewater matrices, removing up to 54% of the phosphate present in natural wastewater within 1 min, with an energy input of only 0.04 kWh.m^-3. After 1 min, phosphate removal followed a zero-order rate law in the 1 min - 30 min range. The zero-order rate constant (k) appears to depend upon differences in wastewater composition, where a faster rate constant is associated with higher Cl^- and NH₄⁺ concentrations, lower Ca²⁺ concentrations, and higher organic carbon content. The sacrificial Mg anode showed the lowest corrosion resistance in the natural industrial wastewater source, with an increased corrosion rate (v_corr) of 15.8 mm.y^-1 compared to 1.9-3.5 mm.y^-1 in municipal wastewater sources, while the Tafel slopes (β) showed a direct correlation with the natural wastewater composition and origin. An overall improvement of water quality was observed where important water quality parameters such as total organic carbon (TOC), total suspended solids (TSS), and turbidity showed a significant decrease. An economic analysis revealed costs based upon experimental Mg consumption are estimated to range from 0.19 $.m^-3 to 0.30 $.m^-3, but costs based upon theoretical Mg consumption range from 0.09 $.m^-3 to 0.18 $.m^-3. Overall, this study highlights that water chemistry parameters control nutrient recovery, while electrochemical treatment does not directly produce potable water, and that economic analysis should be based upon experimentally-determined Mg consumption data. Synopsis Statement: Magnesium-driven electrochemical precipitation of natural wastewater sources enables fast kinetics for phosphate removal at low energy input.

Keywords: Corrosion; Electrochemistry; Magnesium; Natural wastewater; Nutrient removal.

MeSH terms

Nutrients
Phosphorus
Waste Disposal, Fluid*
Wastewater*
Water Quality

Substances

Waste Water
Phosphorus