Modelling of the operation of raceway pond reactors for micropollutant removal by solar photo-Fenton as a function of photon absorption

• Raceway pond reactors allow high treatment capacity (40–133 mg/h m2).
• The mathematical model including photon absorption fitted micropollutant removal.
• Operating conditions (Fe and liquid depth) are predicted according to irradiance.
• The photoreactor could be operated up to 20 cm liquid depth (200 L/m2).

Raceway ponds reactors (RPRs) are extensive non-concentrating photoreactors which allow large volumes of water to be treated. They consist of channels where water is set in motion by a paddlewheel system. In this work the effect of solar irradiance on RPR operation to remove micropollutants by solar photo-Fenton was studied. A RPR was used at pilot plant scale (up to 360 L) and the pesticides acetamiprid (ACTM) and thiabendazole (TBZ) were used as a model pollutant mixture (100 μg/L each) in simulated effluent. Averaged UV irradiances ranged from 10 to 30 W/m2 and three values of iron concentration (1, 5.5 and 10 mg/L) were used. Different liquid depths were also used to evaluate the relationship between the rate of photon absorption and pollutant removal. A model was proposed to predict degradation rate and treatment capacity as a function of the volumetric rate of photon absorption (VRPA). Under low irradiance conditions (10 W/m2) the treatment capacity was not sensitive above 10 cm liquid depth, so a low iron concentration should be used (5 mg Fe/L). For high irradiance values (30 W/m2), greater liquid depth (20 cm) and iron concentration (10 mg Fe/L) should be used to take full advantage of photon availability. Treatment capacity values of 133 mg/h m2 can be reached under these conditions.

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