Influence of some parameters on the nitrate formation during ammonia electrooxidation from an effluent generated by fertilizers’ storage and handling facilities

Author(s): Santos, Iranildes D.; Santos, Kawan B.; Oliveira, Luiza M.S.S.; Radino-Rouse, Patrícia; Dutra, Achilles J.B.
Summary: Total ammonia nitrogen (TAN) is present in several types of effluents including drainage waters from fertilizers storage and handling facilities. Several countries have established a maximum accepted value for TAN and nitrate ion concentration to protect the human health and living environment. This way, the objective of this paper was to investigate the influence of some parameters on TAN electrooxidation, without nitrate generation, from a real effluent using an undivided batch electrolytic reactor with recirculation and Ti/RuO2 electrodes. Results indicated that TAN concentration decreased with the increase of electrolysis length of time, for all current densities and chloride concentrations investigated. The increase of current density and chloride ions concentration lead to a shorter electrolysis period. Nitrate formation during TAN degradation in the presence of chloride ions by electrolysis is influenced by pH and residual TAN concentration. Concentration of nitrate ions increased from 29.7 to 711 mg.L-1 after complete TAN degradation, whereas pH increased from 4.6 to 7.8. Under the investigated conditions, electrolysis should be interrupted after 90% of TAN degradation to avoid nitrate formation. 96% of TAN was removed from an effluent sample containing 6.2 mg.L-1 of NaCl after 120 min of electrolysis with a current density of 25 mA.cm-2. Specific energy consumption was 40.7 kWh.m-3 with a cost of US$ 2.30/m-3.
Journal: Journal of Environmental Chemical Engineering
Year: 2019
Volume: v. 7
Pages: p. 1-23
DOI: https://doi.org/10.1016/j.jece.2019.103123
Year of publication: 2019
Available at: https://www.sciencedirect.com/science/article/pii/S2213343719302465?via%3Dihub
Publisher and ISSN: Elsevier