A critical evaluation of the use of accumulated energy as a parameter for the scale‐up of solar photo‐reactors during the treatment of simulated industrial wastewater by solar photo‐Fenton

BACKGROUND: This work presents a critical evaluation of the use of accumulated energy (QUV) as a parameter for the scale‐up of solar photoreactors. The combined effect of initial pollutant load, iron concentration and UV radiation on industrial wastewater treatment by solar photo‐Fenton was investigated to identify photolimitation and photosaturation conditions. RESULTS: The assays were carried out using a flat‐plate collector (photoreactor with 12 and 20 mg L⁻¹ of iron under average solar UVA irradiances in the range from 16 to 27 W m⁻². In effluents with low initial organic load (45–90 mg L⁻¹), the effect of the initial Fenton reaction was predominant against the contribution of solar radiation. Conversely, the contribution of solar radiation to the process performance was greater in effluents with the highest initial organic load (180–270 mg L⁻¹). Within the range of solar radiation investigated, the process was photolimited when carried out with 20 mg L⁻¹ of iron; however, with 12 mg L⁻¹ of iron the process became photosaturated at irradiances above 15 W m⁻². CONCLUSIONS: Under photosaturation, the extra energy available that cannot be absorbed by the catalyst resulted in ca 60% overestimation of QUV, which can finally lead to 20–30% cost overrun due to photoreactor oversize. © 2021 Society of Chemical Industry