Publications by authors named "Andreas K Benekos"

2 Publications

  • Page 1 of 1

Nitrate removal from groundwater using a batch and continuous flow hybrid Fe-electrocoagulation and electrooxidation system.

J Environ Manage 2021 Nov 28;297:113387. Epub 2021 Jul 28.

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.

During the last two decades nitrate contaminated groundwater has become an extensive worldwide problem with wide-reaching negative effects on human health and the environment. In this study, a combination of electrocoagulation (EC) and electrooxidation (EO) was studied as a denitrification process to efficiently remove nitrates and ammonium (a by-product produced during EC) from real polluted groundwater. Initially, EC experiments under batch operating mode were performed using iron electrodes at different applied current density values (20-40 mA cm). Nitrate percentage removal of 100 % was recorded, however high ammonium concentrations were performed (4.5-6.5 mg NH-Ν L). Therefore, a continuous flow system was examined for the complete removal of both nitrates and EC-generated ammonium cations. The system comprised an EC reactor, a settling tank and an EO reactor. The applied current densities to the EC process were the same as those in the batch experiments, while the volumetric flow rates were 4, 6 and 8 mL min. Regarding the current density of the EO process was kept constant at the value of 75 mA cm. The percentage nitrate removal recorded during the EC process ranged between 52.0 and 100 %, while the NH-N concentration at the outlet of the EO reduced significantly (53-100 %) depending on the applied current density and the volumetric flow rate. Also, the dissolved iron concentration in the treated water was always below the legislated limit of 0.2 mg L (up to 0.027 mg L). These results indicate that the proposed hybrid system is capable of denitrifying real nitrate contaminated groundwater without generating toxic by-products, therefore making the water suitable for human consumption.
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http://dx.doi.org/10.1016/j.jenvman.2021.113387DOI Listing
November 2021

Combined electrocoagulation and electrochemical oxidation treatment for groundwater denitrification.

J Environ Manage 2021 May 10;285:112068. Epub 2021 Feb 10.

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:

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-N concentration (25, 35, 45, 55 mg L) and applied current density (10, 20 mA cm) 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-N L (for initial NO-N of 25 mg L). Therefore, EO was examined to oxidize the ammonium cations to nitrogen gas on iridium oxide coated titanium electrodes (IrO/Ti) anode surface. The effects of cathode material (aluminum, stainless steel), total current density and anode surface area (3.3-30 mA cm and 12-36 cm, respectively) were investigated, and lead to NH-N percentage removals of between 25% (10 mA cm, 12 cm) and 100% (30 mA cm, 24 cm) for an initial NH-N concentration of 10 mg L. The optimum EC (20 mA cm, natural initial pH 7.5-7.8) and EO parameters (30 mA cm, 24 cm surface area anode, Al cathode) were combined into a hybrid system to treat two real nitrate-polluted groundwaters with initial NO-N concentrations of 25 and 75 mg L. Results revealed that the proposed hybrid treatment system can be used to efficiently remove nitrate from groundwaters.
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http://dx.doi.org/10.1016/j.jenvman.2021.112068DOI Listing
May 2021
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