Combined electrocoagulation and electrochemical oxidation treatment for groundwater denitrification.

Autor: Benekos AK; Department of Chemical Engineering, University of Patras, Rio, GR-26504, Patras, Greece., Tsigara M; Department of Chemical Engineering, University of Patras, Rio, GR-26504, Patras, Greece., Zacharakis S; Department of Chemical Engineering, University of Patras, Rio, GR-26504, Patras, Greece., Triantaphyllidou IE; Department of Chemical Engineering, University of Patras, Rio, GR-26504, Patras, Greece., Tekerlekopoulou AG; Department of Environmental Engineering, University of Patras, 2 G. Seferi Str., GR-30100, Agrinio, Greece., Katsaounis A; Department of Chemical Engineering, University of Patras, Rio, GR-26504, Patras, Greece., Vayenas DV; Department of Chemical Engineering, University of Patras, Rio, GR-26504, Patras, Greece; Institute of Chemical Engineering Sciences (ICE-HT), Stadiou Str., Platani, GR-26504, Patras, Greece. Electronic address: dvagenas@upatras.gr.
Jazyk: angličtina
Zdroj: Journal of environmental management [J Environ Manage] 2021 May 01; Vol. 285, pp. 112068. Date of Electronic Publication: 2021 Feb 10.
DOI: 10.1016/j.jenvman.2021.112068
Abstrakt: Electrocoagulation (EC) with an aluminum electrode arrangement as anode-cathode was applied to denitrify groundwater and electrooxidation (EO) was examined as a post-treatment step to remove the produced by-products. Initially, EC experiments were performed under batch operating mode using artificially-polluted tap water to investigate the effects of initial pH (5.5, 7.5, 8.5), initial NO 3 - -N concentration (25, 35, 45, 55 mg L -1 ) and applied current density (10, 20 mA cm -2 ) on process efficiency. The effect of initial solution pH on ammonium cation concentration was also investigated as their generation (as a by-product) is the main drawback preventing wide-scale application of these treatment processes. Experimental results revealed high nitrate removal percentages (up to 96.3%) for initial pH 7.5 and all initial concentrations and current densities, while the final ammonium concentrations ranged between 5.3 and 9.2 mg NH 4 + -N L -1 (for initial NO 3 - -N of 25 mg L -1 ). Therefore, EO was examined to oxidize the ammonium cations to nitrogen gas on iridium oxide coated titanium electrodes (IrO 2 /Ti) anode surface. The effects of cathode material (aluminum, stainless steel), total current density and anode surface area (3.3-30 mA cm -2 and 12-36 cm 2 , respectively) were investigated, and lead to NH 4 + -N percentage removals of between 25% (10 mA cm -2 , 12 cm 2 ) and 100% (30 mA cm -2 , 24 cm 2 ) for an initial NH 4 + -N concentration of 10 mg L -1 . The optimum EC (20 mA cm -2 , natural initial pH 7.5-7.8) and EO parameters (30 mA cm -2 , 24 cm 2 surface area anode, Al cathode) were combined into a hybrid system to treat two real nitrate-polluted groundwaters with initial NO 3 - -N concentrations of 25 and 75 mg L -1 . Results revealed that the proposed hybrid treatment system can be used to efficiently remove nitrate from groundwaters.
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Databáze: MEDLINE
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