Treatment of a synthetic colored effluent in raceway reactors: The role of operational conditions on the environmental performance of a photo-Fenton process

Dorian Prato-Garcia; Angélica Robayo-Avendaño

doi:10.1016/j.scitotenv.2019.134182

Treatment of a synthetic colored effluent in raceway reactors: The role of operational conditions on the environmental performance of a photo-Fenton process

Sci Total Environ. 2019 Dec 20:697:134182. doi: 10.1016/j.scitotenv.2019.134182. Epub 2019 Sep 1.

Authors

Dorian Prato-Garcia¹, Angélica Robayo-Avendaño²

Affiliations

¹ Universidad Nacional de Colombia, Sede Palmira, Facultad de Ingeniería y Administración, Carrera 32 No. 12 - 00, Chapinero, Vía Candelaria, Palmira, Valle del Cauca, Colombia. Electronic address: dpratog@unal.edu.co.
² Universidad Santiago de Cali, Campus Pampalinda, Facultad de Ingeniería, Calle 5 No. 62-00, Cali, Valle del Cauca, Colombia.

PMID: 32380627
DOI: 10.1016/j.scitotenv.2019.134182

Abstract

This study assessed the environmental and economic performance of a photo-Fenton process in a raceway reactor at laboratory scale. For the best operational condition (BOC) identified (dye = 55.0 mg/L, H₂O₂/dye = 0.862 mg/L, Fe²⁺/dye = 0.184) a carbon footprint (CFP) of 1.335 kg CO₂ Eqv/m³ was obtained. Consumption of electrical energy, construction materials, and reagents represent 97.2% (1.298 kg CO₂ Eqv/m³) of the CFP. Similarly, ReCiPe-2016 v1.1 evidenced that these activities play an important role on the environmental performance of the process because their relative impact ranged from 96.5% to 99.7% at least in 14 of the 18 categories considered by this method. It should be noted that the CFP is scarcely sensitive to variations in the use of cement, steel, H₂O₂, and NaOH as a 50.0% increase in their expenditure increases the CFP in 4.4%, 5.0%, 5.9%, and 7.2%, respectively. A 50.0% increment in electricity consumption increased the CFP in 20.7% whereas categories related to acidification, eutrophication, resources depletion, and toxicity-related impacts had significant increments (20.0%-34.0%) in the emissions of substances used for impact characterization. BOC led to the lowest treatment cost (US$0.540/m³) and a CFP between 5- and 10-times lower than that reported for solar tubular reactors. Also, higher proportions of H₂O₂ (H₂O₂/dye = 1.200-1.800) and Fe²⁺ (Fe²⁺/dye = 0.200-0.300) increased cost in 1.9%-5.6% but reduced the CFP in 1.2%-3.7%. Finally, our results evidenced that it is possible to increase the raceway reactor's capacity by increasing the depth of the reactor without affecting the effluent quality. When the depth of the reaction medium went from 3 cm to 6 cm, the treatment capacity (TC) was increased 102.4%, and a 33.3% diminution in the CFP and of 29.1% in the treatment cost occurred. An increase from 3 cm to 9 cm rose the TC up to 204.4% and reduced the CFP (44.4%) and treatment cost (39.3%).

Keywords: Dyes; IPCC; Life cycle assessment; Raceway reactor; ReCiPe-2016; Solar photo-Fenton.