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

Abstract 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/m 2 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/m 2 ) 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/m 2 ), 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 m 2 can be reached under these conditions.