Search

This work studies the effect of treatment period on remediation efficiency in an oxyfluorfen-polluted soil through electro-bioremediation technology. Five lab-scale experimental plants were started up simultaneously, operated under an electric field of 1.0 V cm−1 with a polarity reversal frequency of 2 day−1 and disconnected at different times (2, 4, 6, 11 and 24 weeks); these plants underwent post mortem characterization after their operation period. Various parameters were monitored in the electrolyte wells during the experiments. The obtained results indicate that despite the low reproducibility of pH and conductivity in the wells (not in soil), the main conclusions that can be drawn for the different plants are sound and hence have acceptable reproducibility. Polarity reversal allowed suitable conditions for microbial life in terms of pH, but nutrients were also depleted in the soil, which leads to a decrease in the total population of microorganisms during treatment. For treatment periods of less than 10 weeks, there was an appreciable population of microorganisms in the soil, which reached oxyfluorfen removal levels of up to 40%. Longer reaction times were ineffective, and this was related to the much lower concentration of microorganisms. In comparing these results to those obtained in conventional soil bioremediation technology, the application of polarity-reversed electric current led to an increase in the average removal of oxyfluorfen from 0.11 to 0.17 mg kg−1 day−1 but a much higher decrease in the active microorganism population from 88.0 ± 9.0 to 41.0 ± 6.0% of the initial seeded value.

This work studies the feasibility of the periodic polarity reversal strategy (PRS) in a combined electrokinetic-biological process for the remediation of clayey soil polluted with a herbicide. Five two-weeks duration electrobioremediation batch experiments were performed in a bench scale set-up using spiked clay soil polluted with oxyfluorfen (20 mg kg. Additionally, two complementary reference tests were done: single bioremediation and single electrokinetic. The microbial consortium used was obtained from an oil refinery wastewater treatment plant and acclimated to oxyfluorfen degradation. Main soil conditions (temperature, pH, moisture and conductivity) were correctly controlled using PRS. On the contrary, the electroosmotic flow clearly decreased as increased. The uniform soil microbial distribution at the end of the experiments indicated that the microbial activity remained in every parts of the soil after two weeks when applying PRS. Despite the adapted microbial culture was capable of degrade 100% of oxyfluorfen in water, the remediation efficiency in soil in a reference test, without the application of electric current, was negligible. However, under the low voltage gradients and polarity reversal, removal efficiencies between 5% and 15% were obtained, and it suggested that oxyfluorfen had difficulties to interact with the microbial culture or nutrients and that PRS promoted transport of species, which caused a positive influence on remediation. An optimal, Este trabajo estudia la viabilidad de la estrategia de inversión periódica de polaridad (PRS) en un proceso combinado electrocinético-biológico para la remediación de suelos arcillosos contaminados con un herbicida. Se realizaron cinco experimentos por lotes de electrobiorremediación de dos semanas de duración en una instalación a escala de banco utilizando suelo arcilloso con púas contaminado con oxifluorfeno (20 mg kg. Adicionalmente, se realizaron dos pruebas complementarias de referencia: biorremediación simple y electrocinética simple . El consorcio microbiano utilizado fue obtenido de una planta de tratamiento de aguas residuales de una refinería de petróleo y aclimatado a la degradación del oxifluorfeno. Las principales condiciones del suelo (temperatura, pH, humedad y conductividad) se controlaron correctamente mediante PRS. Por el contrario, el flujo electroosmótico disminuyó claramente a medida que aumentado. La distribución microbiana uniforme del suelo al final de los experimentos indicó que la actividad microbiana permaneció en todas las partes del suelo después de dos semanas al aplicar PRS. A pesar de que el cultivo microbiano adaptado fue capaz de degradar el 100% del oxifluorfeno en el agua, la eficiencia de remediación en el suelo en una prueba de referencia, sin la aplicación de corriente eléctrica , fue insignificante. Sin embargo, bajo los gradientes de bajo voltaje y la inversión de polaridad, se obtuvieron eficiencias de remoción entre el 5% y el 15%, y sugirió que el oxifluorfeno tenía dificultades para interactuar con el cultivo microbiano o los nutrientes y que el PRS promovió el transporte de especies, lo que provocó una influencia positiva. sobre la remediación. Un óptimo