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    Process characterization and pretreatment of container and drum cleaning industry wastewater using a heat-activated persulfate oxidation process
    (Wiley, 2023) Gunes, Elcin; Cifci, Deniz Izlen; Celik, Suna Ozden
    The aim of this study was to treat wastewater from washing, cutting or crushing of intermediate bulk containers (IBCs), steel drums and plastic drums, using the sulfate radical-based oxidation method. In this study, it was planned to make the wastewater suitable for activated sludge treatment by applying neutralization after a sulfate radical-based oxidation process. Samples were taken from the industry three times to study these treatment processes. To determine the optimum conditions in the study, chemical oxygen demand (COD), removal efficiency was calculated, and optimum temperature, optimum time, and optimum persulfate dose were determined. Since the washing is done with hot water in the industry, the thermal activation method was used for the activation of persulfate. In the results of the study, COD removal efficiency, and total organic carbon (TOC), biochemical oxygen demand (BOD), total nitrogen (TN), total phosphorus (TP), and potentially toxic metal(s) removal efficiency was measured in three wastewater samples. According to the results of the study, the temperature at which the best COD removal efficiency was observed was 70 degrees C, the COD/S2O82- ratio was 1:2, and the contact time was 5 h. As a result of the study, it has been revealed that such wastewater can be given to the activated sludge after sulfate radical-based oxidation and neutralization in the same existing reactor instead of the existing FeCl3 process.
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    The Release Potential of Microplastics from Face Masks into the Aquatic Environment
    (Mdpi, 2023) Celik, Suna Ozden
    Since the COVID-19 pandemic, a huge number of face masks have been used to prevent the spread of the coronavirus on a global scale. Unfortunately, several studies have reported the presence of used face masks in marine litter in different countries around the world. Face masks produced from synthetic polymers can increase the environmental burden and contradict sustainability. This study aimed to investigate the environmental behavior of face masks when exposed to natural environmental conditions following improper disposal. New and naturally aged surgical and FFP2 masks were exposed to deionized water (DI) and sea water conditions to understand the environmental behavior of face masks when exposed to different environmental conditions. Following natural aging and DI and sea water exposure, face masks were characterized with Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM), and compared with new masks. According to the results, the middle layers of both mask types were exposed to more severe degradation. Aging resulted in higher microplastic (MP) release than new masks in DI and seawater for both types of face masks. Compared to new ones, aging and seawater exposure caused 11 to 13 and 14 to 22 times higher MP release from surgical and FFP2 face masks, respectively. Following seawater exposure, aged FFP2 mask released higher amounts of MP (4.36-6.20 x 10(6)) than aged surgical masks (4.03-5.45 x 10(6)). According to the results, a significant portion of the released MPs were <10 mu m for both types of masks. However, when aged FFP2 masks were exposed to seawater, a remarkable increase was found in the fraction of 10-50 mu m and 50-100 mu m, suggesting that aged FFP2 masks also became fragmented in seawater conditions. FTIR and SEM analyses confirmed the transformation in the structure and chemical composition of the materials. A significant change was observed in chemical and physical structure of the masks after being exposed to weathering conditions in a relatively short period of time (one month).