Postgraduate Program in Ecology and Conservation, Federal University of Paraná, Curitiba, Brazil.
Photochem Photobiol Sci. 2018 Apr 18;17(4):517-521. 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 H2O2 and 5 mg L-1 of Fe2+ (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.
水体中由于废水排放、肥料和其他投入物导致的营养物质浓度增加，可能导致人为富营养化，增加初级生产力，给环境带来众所周知的严重后果（如过度的大型植物和微藻生长）。大多数水生生态系统中浮游植物控制策略在氯化后会导致金属积累或有毒副产物的形成。关于这个问题，光芬顿工艺（通常应用于废水处理和多种污染物的降解）已经被研究用于水和废水的消毒。然而，直到现在，它在微藻失活中的应用还没有被报道。因此，本工作旨在评估该工艺在灭活微藻方面的有效性，使用钝顶螺旋藻作为模型。在实验室规模上进行光芬顿实验，细胞浓度为 105 个/mL，H2O2 浓度为 20mg/L，Fe2+浓度为 5mg/L（与草酸络合）。采用细胞浓度和生长抑制试验（GIT）来评估工艺效率，并用扫描电子显微镜（SEM）分析细胞形态的任何变化。在进行光芬顿反应后，研究了反应物和辐射的单独贡献。在光芬顿反应过程中，细胞浓度没有明显降低，但 SEM 图像表明可能存在形态变化，GIT 显示在暴露 30 分钟后细胞活力丧失。仅暴露于过氧化氢时，也观察到对细胞生长的影响。
