Simultaneous Removal of Ammonia and Nitrate from Wastewater Using a Pulse Electrolysis Technique

Abstract

The Environmental Protection Agency considers ammonia and nitrate as large-scale threats to environmental quality and human health, causing impaired air quality, surface water eutrophication, and other serious health problems. This work examines the viability of using a pulse electrolysis technique to accomplish the simultaneous removal of ammonia and nitrate in an undivided flow cell using CuNi/PtIr supported on carbon electrocatalysts (CuNi/PtIr/C). Different series of PtIr/C and CuNi/C compositions were examined, and it was found that among all series of the synthesized catalysts, 60% Pt9Ir/C and 40% Cu9Ni/C had greater activity toward ammonia oxidation reaction and nitrate reduction reaction, respectively. Throughout the pulsing potentials, the nitrogen contaminants were gradually removed with the overall reaction that generated harmless nitrogen and hydrogen gases. The average ammonia and nitrate removal rates were 5.17 ppm-ammonia and 0.074 ppm-nitrate/min, respectively. The selectivity of nitrate to ammonia was 82% with an average nitrate removal rate of 65%. The catalysts exhibited pronounced stability after 10 cycles of pulse electrolysis.

Assessment of Effluent Wastewater Quality and the Application of an Integrated Wastewater Resource Recovery Model: The Burgersfort Wastewater Resource Recovery Case Study

“…This showed increased hydrogen ions in the wastewater affecting the pH, decomposition activity, and increasing NH3 gas retention. Dey et al [40] and Hariri and Botte [41] observed that untreated organic matter in WRRFs decomposes over time; this results in pH imbalances, as well as the proliferation of NH3. Temperature had a negative significant loading…”

“…This showed increased hydrogen ions in the wastewater affecting the pH, decomposition activity, and increasing NH 3 gas retention. Dey et al [40] and Hariri and Botte [41] observed that untreated organic matter in WRRFs decomposes over time; this results in pH imbalances, as well as the proliferation of NH 3 . Temperature had a negative significant loading (component loading <−0.5); this indicated low temperature levels which lead to minimal microbial reactions and the extirpation of gases such as NH 3 , CO 2 , and CH 4 .…”

“…The significant positive loading of NO 3 − signified the prevalence of nitrogen and the failure of removal. Dey et al [40] and Hariri and Botte [41] reported that NO 3 − is positively influenced by nitrogen in water, thus resulting in abundant NO 3 − levels.…”

Recent Advances in Ammonia Electrolysis for Sustainable Hydrogen Generation

“…More recently Hariri and Botte demonstrated electrocatalysts combination (PtIr, CuNi) and a cell configuration that enables the simultaneous removal of both ammonia and nitrate from wastewater with hydrogen cogeneration. 26 Implementing the NH 3 electrolysis method kills two birds in one stone more efficient H 2 production and addresses wastewater problems (minimizing environmental impact air, water, and land). The source of ammonia comes from various industrial and agricultural waste streams, which not only provides feedstock for hydrogen production but also mitigates environmental pollution.…”

Local tensile strain boosts the electrocatalytic ammonia oxidation reaction

“…The electrocatalytic ammonia oxidation reaction (EAOR) has potential applications in the fields of energy conversion and wastewater treatment. 1–4 In particular, considerable attention has been paid to the applications of ammonia fuel cells and on-line hydrogen production in recent years due to the remarkable advantages of ammonia as an energy carrier regarding its high hydrogen content, carbon-free nature, easy storage and transportation. 5–7 In the EAOR, ammonia is expected to be oxidized to N 2 at the anode, and water is reduced to H 2 at the cathode:Anode: 2NH 3 (aq) + 6OH − → N 2 + 6H 2 O + 6e − E ° = −0.77 V vs. SHECathode: 6H 2 O + 6e − → 3H 2 + 6OH − E ° = −0.83 V vs. SHEOverall reaction: 2NH 3 (aq) → N 2 + 3H 2 E ° = −0.06 V…”