Surfactant enhanced soil washing (SW) and soil flushing are efficient processes for polycyclic aromatic hydrocarbons removal from contaminated soils. However, management of soil washing solutions is a complex challenge for environmental engineering. This study investigated the implementation of a combined process coupling anodic oxidation (AO) – an electrochemical advanced oxidation process – and aerobic biological treatment (BT) for proper handling of a synthetic SW solution containing phenanthrene, Tween® 80 and humic acids. As a sole process, AO required a treatment duration of 5 h and a current intensity of 1 A to remove 95% of phenanthrene and Tween® 80 as well as 71% of COD. Such operating conditions resulted in high electrical energy consumption (67 kWh (kg COD)-1). In contrast, BT alone allowed a total degradation of both phenanthrene and Tween® 80, but an insufficient removal of COD (44%) was observed due to the production of non-biodegradable by-products. In order to promote synergistic effects, AO and BT were combined and two different treatment strategies were investigated depending on whether AO was used as pre- or post-treatment. The production of more biodegradable by-products was observed after short AO pre-treatment (3 h, 500 mA), resulting in 80% COD removal after BT. The opposite combination (with AO post-treatment) led to 76% and 93% COD removal after the AO post-treatment at 500 mA for 3 h and 5 h, respectively. Therefore, such combined process appears as a sustainable way to enhance both quality of treated effluent and process cost-effectiveness.

Combination of anodic oxidation and biological treatment for the removal of phenanthrene and Tween 80 from soil washing solution

TRELLU, Clement;GANZENKO, Oleksandra;PAPIRIO, Stefano;ESPOSITO, Giovanni;
2016-01-01

Abstract

Surfactant enhanced soil washing (SW) and soil flushing are efficient processes for polycyclic aromatic hydrocarbons removal from contaminated soils. However, management of soil washing solutions is a complex challenge for environmental engineering. This study investigated the implementation of a combined process coupling anodic oxidation (AO) – an electrochemical advanced oxidation process – and aerobic biological treatment (BT) for proper handling of a synthetic SW solution containing phenanthrene, Tween® 80 and humic acids. As a sole process, AO required a treatment duration of 5 h and a current intensity of 1 A to remove 95% of phenanthrene and Tween® 80 as well as 71% of COD. Such operating conditions resulted in high electrical energy consumption (67 kWh (kg COD)-1). In contrast, BT alone allowed a total degradation of both phenanthrene and Tween® 80, but an insufficient removal of COD (44%) was observed due to the production of non-biodegradable by-products. In order to promote synergistic effects, AO and BT were combined and two different treatment strategies were investigated depending on whether AO was used as pre- or post-treatment. The production of more biodegradable by-products was observed after short AO pre-treatment (3 h, 500 mA), resulting in 80% COD removal after BT. The opposite combination (with AO post-treatment) led to 76% and 93% COD removal after the AO post-treatment at 500 mA for 3 h and 5 h, respectively. Therefore, such combined process appears as a sustainable way to enhance both quality of treated effluent and process cost-effectiveness.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11580/55974
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