Application of high intensity UVC-LED for the removal of acetamiprid with the photo-Fenton process

• A novel high intensity UVC-LED (20 W/m2) was used to run the photo-Fenton process.
• Acetamiprid removal was studied in synthetic water at acidic and natural pH.
• The contribution of H2O2 and Fe to generate radicals was assessed through the volumetric photon absorption (VPRA).
• At natural pH acetamiprid was removed in 20 min using a sequential iron dosing strategy.
• High intensity LEDs reduce the required effective reactor surface area when compared to low intensity LEDs.

Research into the use of light-emitting diodes (LEDs) for wastewater treatment has increased in recent years. LEDs are more efficient than other UV lamps because of their reduced heat dissipation and much longer life span. However, most of the UVC-LEDs that are currently available are of such low intensity that the large number of bulbs required for effective treatment of wastewater streams makes their application uneconomic. The development of higher intensity UVC-LEDs may therefore lead to more feasible technology options for wastewater treatment with UV-based advanced oxidation processes (AOPs). The aim of this work was to study the efficiency of high-intensity UVC-LED lamps (20 W/m2) for the removal of micropollutants with the photo-Fenton process. The pesticide acetamiprid was used as model pollutant at a concentration of 100 μg/L in synthetic secondary effluent due to its recalcitrant nature. Degradation using a low-pressure UVC-lamp (LPL) was also assessed for comparative purposes. The process was operated at pH 2.8 and at natural pH. The volumetric photon absorption (VRPA) was calculated for the results at acidic pH, where the catalyst was soluble, to investigate the influence of iron and hydrogen peroxide concentrations on acetamiprid degradation, based on their absorption for both systems. A model was proposed and results indicated that the contribution of both hydrogen peroxide and iron to the generation of radicals was the same in the LED system. At natural pH, the high intensity LED system was effective in the removal of acetamiprid, achieving degradation in 20 min adding 1 + 1 + 1 mg Fe/L (sequential iron dosage) and 12 mg H2O2/L.