Evaluation of the prediction of micropollutant elimination during bromide ion-containing industrial wastewater ozonation using the ROH, O3 value

The composition of the wastewater matrix influences the oxidation potential of ozonation, a technique widely recognized efficient removal of micropollutants. Here, we developed a chemical kinetic model to determine the ozone dose required to minimize bromate production in wastewater containing bromine ions while achieving target removal rates. In wastewater ozonation, ozone decomposition comprises instantaneous ozone consumption and subsequent decomposition at first-order reaction rates. Under the injection condition of 1.5 g O3/g dissolved organic carbon (DOC), the instantaneous ozone demand was 62.7% of the injection concentration, and it increased proportionally with increasing injected ozone concentration. Ozone and hydroxyl radical exposures were proportional to the initial ozone dose, while hydroxyl radical exposure was proportional to ozone exposure, and the deviation was relatively high at 1.0-1.5 g O3/g DOC. The calculated hydroxyl radical exposure was 3.0 × 10-10 to 5.3 × 10-10 M s. Ozone and hydroxyl radicals are highly correlated with the ratio of ozone dose to organic matter concentration. Therefore, a trace substance removal rate evaluation model combined with the ROH, O3 model and a bromate generation model were also considered. For ibuprofen, the ozone dose for achieving the target removal rate of 80% while maintaining the bromate concentration below 50 μg L-1 was suitable in the operating range of 0.86 g O3/g DOC or more. The proposed method provides a practical operation strategy to calculate the appropriate ozone dose condition from the target compound removal rate prediction and bromate generation models considering the ratio of ozone dose to organic matter concentration in the incoming wastewater.

Evaluation of vertical distribution characteristics of microplastics under 20 μm in lake and river waters in South Korea

Following the alarming reports of microplastic pollution in the marine environment, increased attention has been given to microplastics in other environmental media. Despite the attention, there is limited research available on the depth-distribution of microplastics in freshwater. Specifically, in the case of water sources used for drinking or tap, the height of intake facilities varies, and it is highly likely that there is a correlation between the vertical distribution of microplastics and these water intake structures. Further, because the size of microplastics varies widely in the environment, the commonly used sampling devices are not suitable for selectively extracting microplastics without causing cross-contamination. Thus, we developed a suitable device for microplastics of size 5-20 µm and studied microplastic distribution in freshwater at various depths by considering various types of microplastics and aqueous systems. Lake and river, two major water sources, were selected for the study of microplastics distribution in water system. The microplastic distribution characteristics in both water systems showed that polypropylene and polyethylene were the most abundant across all depths because of their production volume. Plastic types with higher density were found only at the lower layers, and polystyrene was found in the upper layers because of the environmental effects on its buoyancy caused pore diameter and surface area. The lake and river had higher microplastic distribution in the lower layer and upper layer, respectively. This was because the flow rate in river was higher than that of lake. The higher flow rate reduced the settling velocity in river. Thus, hydrodynamic stability influences the vertical distribution and concentrations of microplastics in the water systems. These results are expected to be used for understanding the behavioral characteristics of microplastics in water systems and to manage water sources.

Microplastics in water systems: A review of their impacts on the environment and their potential hazards

Microplastics, the microscopic plastics, are fragments of any type of plastic that are being produced today as plastic waste originating from anthropogenic activities. Such microplastics are discharged into the environment, and they enter back into the human body through different means. The microplastics spread in the environment due to environmental factors and the inherent properties of microplastics, such as density, hydrophobicity, and recalcitrance, and then eventually enter the water environment. In this study, to better understand the behavior of microplastics in the water environment, an extensive literature review was conducted on the occurrence of microplastics in aquatic environments categorized by seawater, wastewater, and freshwater. We summarized the abundance and distribution of microplastics in the water environment and studied the environmental factors affecting them in detail. In addition, focusing on the sampling and pretreatment processes that can limit the analysis results of microplastics, we discussed in depth the sampling methods, density separation, and organic matter digestion methods for each water environment. Finally, the potential hazards posed by the behavior of aging microplastics, such as adsorption of pollutants or ingestion by aquatic organisms, due to exposure to the environment were also investigated.

Anxiety and Worries of Individuals with Down Syndrome During the COVID-19 Pandemic: A Comparative Study in the UK

The present study explored the effects of the pandemic on individuals with Down Syndrome (DS; n = 67) compared to other groups with Special Education Needs and Disabilities (SEND; n = 48) and their Typically Developing Siblings (TDS; n = 56). In total, 115 caregivers reported on their own anxiety and worries and of their children. Anxiety levels for individuals with DS appeared to be lower compared to other SEND populations and to TDS. In terms of worries, individuals with DS worried more about social-related worries but worried less about family-related aspects compared to the other groups. In sum, individuals with DS might show less anxiety but still worried more about specific aspects related to the impact of COVID-19 pandemic on their lives.

Characterization of marine dissolved organic matter and its effect on ozonation

As the marine industry develops, the importance of seawater treatment process is increasing. To treat seawater, oxidation processes have primarily been used, such as ballast water treatment systems, aquaculture farm operations, aquarium management, and seawater desalination. However, dissolved organic matter in seawater, whose characteristics vary spatially and seasonally, affects the efficiency of oxidation processes. Therefore, in this study, seawater samples were acquired from various locations in the Republic of Korea to understand the spatio-temporal patterns of marine dissolved organic matter. It was reported that the characterization of marine dissolved organic matter using liquid chromatography-organic carbon detector and excitation-emission matrix-parallel factor modeling. Furthermore, the effects of marine dissolved organic matter were evaluated on ozonation, an oxidation process. The results demonstrate that marine dissolved organic matter varies in its aquagenic, pedogenic, and intermediate characteristics based on region and season. These variations affect ozonation by influencing the consumption of oxidants (e.g., bromine). As a result, it was concluded that characterizing marine dissolved organic matter can help improve the effectiveness of oxidation processes, particularly ozonation.

Evaluation of Moringa oleifera seed extract by extraction time: effect on coagulation efficiency and extract characteristic

The seed of Moringa oleifera (MO) is a well-known coagulant used in water and wastewater treatment, especially in developing countries. The main mechanism of MO seed extract in coagulation is the positive protein component for charge neutralization. The method for efficient extraction of MO seed is very important for high coagulation activity. In this study, the effects of extraction mixing speed and extraction time of MO on coagulation activity were evaluated using a distilled water extraction method. Although the rotation per minute for extraction did not affect the coagulation efficiency, the extraction time strongly affected the coagulation efficiency of the extract. To evaluate the characteristic change of MO extract by extraction time, the charge of MO extract and protein characteristic in MO extract were analysed. As the extraction time was short, more positive charge and higher protein content were observed. For detailed protein analysis, the fluorescence spectroscopic study (EEM analysis) was performed. The tryptophan-like peak increased at longer extraction times. For efficient extraction of MO seed, a short extraction time is strongly recommended.

Performance characterization and kinetic modeling of ozonation using a new method: ROH,O3 concept

Ozonation is an effective treatment for removing various organic pollutants from aquatic systems. The R_ct concept, which is defined as the ratio of OH exposure to O₃ exposure, has been widely used to predict the removal efficiency of target compounds, but it has significant variations by water temperature and initial O₃ dose which are crucial parameters in drinking water plant. The R_OH,O3 concept, which is defined as the OH exposure by O₃ consumption, was proposed as a kinetic parameter for characterization and kinetic modeling for ozonation. The R_OH,O3 concept is independent of temperature and initial O₃ dose. A higher R_OH,O3 value indicates a higher OH formation when the same amount of O₃ is consumed in different water samples; therefore, the OH yield from O₃ decomposition of the water samples can be compared using the R_OH,O3 values. The R_OH,O3 concept can also be used to characterize and model the initial ozone demand phase, and it is more convenient method compared to Rct concept. Using the R_OH,O3 concept, the dynamic O₃ and OH kinetics and the removal efficiencies of iopromide and ibuprofen were well predicted (R² = 0.98) over a wide range of experimental conditions (n = 124).

Simulation of Continuous Polymerization in a Modular Intermeshing Co-rotating Twin Screw Extruder

A method of modeling chemical reactions in a modular inter-meshing co-rotating twin screw extruder is described. This is applied to simulate the anionic polymerization of caprolactam. Calculations are made for specific modular screw configurations. The screw configurations included both screw elements and kneading disc blocks. Reaction conversion and temperature rise were calculated along the screw axis. The results are compared to experiment.

Continuous Polymerization of Caprolactam-Polyether Sulfone Solutions in a Twin Screw Extruder to Form Reactive Polyamide–6/Polyether Sulfone Blends and Their Melt Spun Fibers

The continuous anionic polymerization of caprolactam solutions of polyether sulfone in a modular intermeshing co-rotating twin screw extruder has been investigated. The polyether sulfone appears to react with the polymerizing monomer. The polyamide-6/polyether sulfone reactive blends formed have been characterized. Studies were also made of melt spinning reactive blends into oriented filaments. The structure and mechanical properties of the blend melt spun filaments were characterized.

Fluorescence in situ hybridization study of HER-2/neu oncogene amplification in prostate cancer

Prostate cancer is a serious disease affecting men worldwide and treatment compromises the quality of life of prostate cancer patients. We conducted a study of 88 cases of prostate cancer in an attempt to identify prognostic biomarkers that can distinguish aggressive cases that must be treated immediately. HER-2/neu oncogene amplification was initially studied because amplification of this gene has been reported in many other cancers, including those studied in this laboratory. Fluorescence in situ hybridization (FISH) using a HER-2/neu gene probe with a chromosome 17 centromere control probe was performed on formalin-fixed, paraffin-embedded tissues. Of a total of 86 cases successfully analyzed, only 8 (9.3%) were found to be amplified. This frequency was lower than the frequency of amplification found in other cancers studied. Furthermore, no case was found where the level of amplification can be considered high. Only one case was found to have moderate amplification. The rest of the positive cases can all be classified as low amplification. Thus, while we have demonstrated that FISH is a sensitive technique for detecting oncogene amplification, the frequency and level of HER-2/neu amplification detected in prostate cancer seem to be lower than those in most cancers that we studied. In view of the fact that HER-2/neu amplification does not seem to play as significant a role, exploration of other biomarkers in prostate cancer is warranted.