Microplastic is a widespread pollutant in marine and fresh water systems. A major pathway by which microplastics end up in these systems is via storm water. Storm water is generated as precipitation drain off of impenetrable surfaces like paving. Microplastic analysis of storm water make up a good foundation for better understanding what sources and factors contribute to microplastic pollution in marine and fresh water systems. This study puts emphasis on characterization and quantification of microplastics through visual characterization. As visual characterization is a subjective form of analysis, the characterization was performed based on guidelines in order to minimize the risk of identifying false positives. The concentration of microplastic was found to be higher in the current study than in comparison to larger water bodies and storm water streams in less urban areas. Fragments, i.e. irregular shaped particles with the appearance of being broken from a larger piece of litter, were found to be the most abundant type of microplastics, pointing at littering as a major source of microplastics in storm water.

Microplastics are emerging pollutants in the marine environment, including a range of polymers modified by varying quantities of additives and sorbed pollutants, differing in size, colour, and shape. This study focuses on characterization and quantification through visual characterization of microplastics >300 μm in surface water and at 5-meter depth in the Gulf of Bothnia. A comparison between a reference area and an urban impact area was made to estimate if the water is more polluted near rural or industrial areas. The visual characterization was based on general guidelines provided by GESAMP to minimize the risks of identifying false positives. The concentrations of microplastics were found to be similar in the current study in comparison to other studies in the Baltic Sea. There was insufficient evidence to conclude a difference between the reference area and the urban impact area. A key finding in this study was that fragments, i.e. irregular shaped hard particles having appearance of being broken down from a larger piece of litter were the most abundant type of microplastics particles found. The vast majority of the identified polymers by ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy) consisted of Polyethylene (PE) and Polystyrene (PS)

This study aims to detect how many microplastics and what kind are released from the wastewater treatment plant (WWTP) Skebäck, in Örebro. The study was limited to the analysis of three filters with 50 μm mesh size and one filter with 300 μm mesh size. The samples were taken at different times, two in the fall of 2019 and one in the spring of 2020. Visual characterization was used for the quantification of microplastics, and a lower and upper bound was used. The lower bound represents particles that were deemed identifiable as plastic with high certainty, while the upper bound also includes particles that may have been microplastic. An additional ATR-FTIR analysis was performed on selected microplastics >300 μm.  The presence of microplastics in the effluent from Skebäcks WWTP could be confirmed. The quantity of microplastics per m​3​ (MP/m​3​) trapped on the 50 μm filters were quantified in a range between 0 MP/m​3​ to 291 MP/m​3​ for the lower bound, and 72 MP/m​3​ to 435 MP/m​3​ for the upper bound. The 300 μm filter had considerably less microplastics than the 50 μm filter with 1.8 MP/m​3​. The quantification of fibers on the 50 μm filter and 300 μm filters was not possible due to high blank contaminations. According to the concentration of 63 MP/m​3​ of the lower bound count on the 50 μm filters and the amount of water flowing through Skebäck in 2019, 17 818 935 m​3​, 1.1 billion microplastic particles were released into Svartån that year. In comparison the highest value of the upper bound count, 435 MP/m​3​, gave a release of 7.7 billion microplastic particles. Using the concentration of the 300 μm filter 1.8 MP/m​3​, 32 million microplastics/year were released from Skebäck in 2019. The amount of spheres 50-300 μm released in the effluent from Skebäck was estimated to be 3.7 kg in 2019.

Le but du travail est d’analyser l’impact du couple grain/matériau des pièces grainées en injection de polypropylène sur les caractéristiques de la surface et leur Qualité Perçue. En l’absence d’outils préexistants, un système de caractérisation et de prédiction des propriétés d’aspect des « grains » a été développé intégralement. Il comprend un référentiel de caractérisation (à 12 descripteurs) et deux instruments : un panel visuel entraîné spécifiquement et un panel instrumental. Le panel instrumental utilise des mesures issues de 3 instruments. Il a permis d’élaborer 12 modèles prédictifs. En appliquant ce dispositif à un ensemble d’échantillons en polypropylène injecté, il a été possible de dissocier l’influence de l’esthétique du grain (descripteurs de « fantaisie ») de ce qui permet de différencier matières et qualité de réalisation (descripteurs de « brillant »). Une exploration des impacts de la composition des matières, de la topographie des grains et de la réponse de la matière à cette topographie lors de l’injection a été réalisée sur un groupe de 4 grains et 3 matières, pour 3 couleurs. Enfin, une large enquête client a été menée, dont les résultats ont été exploités pour établir comment les caractéristiques évaluées par le panel entrent en relation avec la perception de la qualité. Il apparaît que l’esthétique du grain et son association à la couleur, puis le brillant perçu, impactent majoritairement les jugements de qualité. Quoique prospectif, ce travail permet de développer des « gênes » de grains adaptés à différents types de clientèle en considérant dès le départ l’influence du couple « géométrie du grain - potentiel visuel de la matière ». / The aim of the study is to analyse the impact of texture/material couple of polypropylene injection pieces on the characteristics of the surface and the Perceived Quality. In order to answer this question, we developed a system for the characterization and the prediction of the appearance of the texture. It includes a scale of characterization (composed of 12 descriptors) and two «instruments» of characterization: a visual panel and instrumental panel. The instrumental panel is composed of 12 predictive models of the 12 descriptors. The models are built on sensory ratings and the measures of 3 instruments. The characterization system is used on a set of samples of injected polypropylene making it possible to defines the aesthetics descriptors of the grain (“fantasy” descriptors) and descriptors that differentiate the materials (gloss descriptors). An exploration of the impact of the material composition, the topography of the grains and the response of the material to the topography during the injection moulding was performed on a group of samples with 4 grain, 3 materials and 3 colors. Finally, a large customer survey was conducted. The results have been exploited to establish how the characteristics evaluated by the panel are related with the perception of quality. It appears that the aesthetics of the grain and its association with the color and then its gloss, mostly impact the judgments of quality. Although prospective, this work allows the development of the "genes" of grains suitable for different types of customers, by considering the influence of the couple "grain geometry - visual potential of the material."