Does the photo-Fenton reaction work for microalgae control? A case study with Desmodesmus subspicatus

• Published in: Photochemical & photobiological sciences 2018, Vol.17 (4), p.517-521
• Main Authors: Torres, Mariana de Almeida, de Liz, Marcus Vinicius, Martins, Lucia Regina Rocha, Freitas, Adriane Martins
• Format: Article
• Language: English
• Subjects: Algae; Aquatic ecosystems; Biochemistry; Biomaterials; Case studies; Cell morphology; Chemistry; Contaminants; Cytology; Deactivation; Disinfection; Effluents; Electron microscopy; Eutrophication; Fertilizers; Growth inhibition test; Hydrogen peroxide; Inactivation; Iron; Microalgae; Morphology; Nutrients; Oxalic acid; Photocatalysis; Physical Chemistry; Phytoplankton; Plant Sciences; Radiation; Scanning electron microscopy; Technical Note; Wastewater discharges; Wastewater disposal; Wastewater treatment; Water pollution; Water treatment; Waterborne diseases
• ISSN: 1474-905X; 1474-9092
• DOI: 10.1039/c7pp00443e

Increased concentrations of nutrients in water bodies caused by effluent discharge, fertilizers and other inputs can lead to artificial eutrophication, increasing the primary productivity, bringing well-known and serious consequences to the environment (such as excessive macrophyte and microalgae growth). Most strategies for phytoplankton control in aquatic ecosystems result in metal accumulation or toxic by-product formation after chlorination. Concerning this matter, the photo-Fenton process (usually applied in wastewater treatment and degradation of a variety of contaminants) has been studied for water and effluent disinfection. However, its application in microalgae inactivation has not been reported until now. Therefore, this work aimed to evaluate the process effectiveness in inactivating microalgae, using Desmodesmus subspicatus as a model. Photo-Fenton experiments were carried out at the lab scale, at 105 cells per mL with 20 mg L −1 of H 2 O 2 and 5 mg L −1 of Fe 2+ (complexed with oxalic acid). The cell concentration and Growth Inhibition Test (GIT) were used to evaluate the process efficiency and Scanning Electron Microscopy (SEM) to analyze any alterations in the cell morphology. After performing the photo-Fenton reaction, the individual contribution of the reactants and radiation was investigated. The cell concentration was not significantly reduced during the photo-Fenton reaction, but SEM images indicated possible morphology alterations and the GIT showed the loss of cell viability after 30 minutes of exposure. Effects on the cell growth were also observed when exposed only to hydrogen peroxide. This paper presents the first report of photo-Fenton process application aiming microalgae inactivation, using Desmodesmus subspicatus as model species.