Decontamination of real urban sewage—comparison between Fenton and electrochemical oxidation

• Published in: Environmental science and pollution research international Vol. 29; no. 23; pp. 35061 - 35072
• Main Authors: de Araújo, Jenivaldo L., da Silva, Jaceguai S., Santos, Fábio A. S., de Carvalho, Cenira M., Duarte, José Leandro S., Tonholo, Josealdo, Zanta, Carmem L. P. S.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-05-2022; Springer Nature B.V
• Subjects: Ammonia; Aquatic Pollution; Artemia; Atmospheric Protection/Air Quality Control/Air Pollution; Bioassays; Chemical oxygen demand; Chemical treatment; Chloride ions; Chlorine; Decontamination; Earth and Environmental Science; Ecotoxicology; Electrochemical oxidation; Electrochemistry; Energy consumption; Environment; Environmental Chemistry; Environmental Health; Environmental science; Hydrogen peroxide; Iron; Organic loading; Organic matter; Oxidation; Research Article; Sewage; Toxicity; Turbidity; Waste Water Technology; Wastewater treatment; Water Management; Water Pollution Control; Fenton; Real water treatment; Urban sewage; Toxicity; Electro-oxidation
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-022-18718-w

Advanced oxidation processes have been used for wastewater treatment due to their capacity to reduce the organic loading and for their fast reactions. In this paper, we explore the viability of isolated and sequential use of electrochemical oxidation and Fenton processes into treatment of real raw urban sewage. The electrochemical process was carried out using DSA®-Cl
2
electrodes and factorial planning in order to investigate the influence of pH, current density, and electrolyte. Fenton reaction was also used and H
2
O
2
and Fe
2+
concentration effects were investigated. The efficiency was estimated by chemical oxygen demand (COD) removal and in the optimized conditions the effluent was characterized by turbidity, suspended/dissolved/total solids, ammonia, chloride ions, free chlorine, nitrite, and potassium analysis and bioassays with
Artemia ssp.
and
Lactuca sativa
. The study demonstrated that the use of electrochemical technique followed by Fenton allowed an improvement in the degradation of organic matter and reduction of turbidity and solid content, reaching reductions of 86.8, 96.4, 99.4, 56.1, and 66.7% for COD, turbidity, SS, DS, and TS, respectively. The associated treatment also contributed to the reduction of energy consumption by 74.9%, from the 23.9 kWh m
−3
observed during the electrochemical treatment isolated to the 6 kWh m
−3
during the associated process. All the treatments presented toxicity reduction, with the electrochemical process achieving the best results.
Graphical abstract