Effect of different degradation types on properties of plastic waste obtained from espresso coffee capsules

Photoaging Elevated the Genotoxicity of Polystyrene Microplastics to Marine Mussel Mytilus trossulus (Gould, 1850)

Micro-sized particles of synthetic polymers (microplastics) are found in all parts of marine ecosystems. This fact requires intensive study of the degree of danger of such particles to the life activity of hydrobionts and needs additional research. It is evident that hydrobionts in the marine environment are exposed to microplastics modified by biotic and abiotic degradation. To assess the toxic potential of aging microplastic, comparative studies were conducted on the response of cytochemical and genotoxic markers in hemocytes of the mussel Mytilus trossulus (Gould, 1850) after exposure to pristine and photodegraded (UV irradiation) polystyrene microparticles (µPS). The results of cytochemical tests showed that UV-irradiated µPS strongly reduced metabolism and destabilized lysosome membranes compared to pristine µPS. Using a Comet assay, it was shown that the nuclear DNA of mussel hemocytes showed high sensitivity to exposure to both types of plastics. However, the level of DNA damage was significantly higher in mussels exposed to aging µPS. It is suggested that the mechanism of increased toxicity of photo-oxidized µPS is based on free-radical reactions induced by the UV irradiation of polymers. The risks of toxic effects will be determined by the level of physicochemical degradation of the polymer, which can significantly affect the mechanisms of toxicity.

Biodegradation of polyethylene in digestive gland homogenates of marine invertebrates

Вiotic factors may be the driving force of plastic fragmentation along with abiotic factors. Since understanding the processes of biodegradation and biological depolymerization of plastic is important, a new methodological approach was proposed in this study to investigate the role of marine invertebrate digestive enzymes in plastic biodegradation. The aim of this study is to evaluate the possibility of enzymatic biodegradation of polyethylene fragments in the digestive gland homogenate of marine invertebrates differing in their feeding type (Strongylocentrotus nudus, Patiria pectinifera, Mizuhopecten yessoensis). Significant changes are found in the functional groups of the polymer after 3 days of incubation in the digestive gland homogenates of the studied marine invertebrates. A significant increase in the calculated CI (carbonyl index) and COI (сarbon-oxygen index) indices compared to the control sample was observed. The results suggest that digestive enzymes of studied organisms may play an important role in the biogeochemical cycling of plastic.

Sustainability issues along the coffee chain: From the field to the cup

The coffee industry is one of the most important commercial value chains worldwide. Nonetheless, it is also associated to several social, economic, and environmental concerns that impair its sustainability. The present review is focused on these main sustainability concerns from the field to the coffee cup, as well as on the strategies that are being developed and/or implemented to attain sustainability and circular economy principles in the different chain segments. In this context, distinct approaches have been applied, such as sustainable certifications (e.g., voluntary sustainability standards), corporate sustainability initiatives, direct trade, relationship coffee concepts, geographical indication, legislations, waste management, and byproducts valorization, among others. These strategies are addressed and discussed throughout this review, as well as their recognized advantages and limitations. Overall, there is still a long way to go to attain the much-desired sustainability in the coffee chain, being essential to join the efforts of all actors and entities directly or indirectly involved, namely, producers, retailers, roasters, governments, educational institutions (such as universities and scientific research institutes), and organizations.

Occurrence, impact, toxicity, and degradation methods of microplastics in environment-a review

Microplastic defines as a tiny plastic particle that has a size of less than 5 mm and is ubiquitous in the environment. Due to the tiny size, this microplastic adversely affected the environment, notably aquatic life via ingestion, choking, and entanglement. This microplastic is arduous to degrade as it takes a thousand years due to the properties of plastic itself and consequently remains in nature. In dealing with microplastic issues, this paper reflects the occurrence, impact, toxicity, and degradation methods of microplastics in the environment including physical, chemical, and biological treatments. Here, the physical treatment methods include incineration treatment, ultraviolet (UV), and photocatalytic. The incineration process contributes to environmental pollution due to the release of toxic gases into the atmosphere. In addition, chemical treatments for plastic waste are the degradation process involving chemical additives such as ethylene glycol (EG), nano-magnesium oxide (MgO), diethylene glycol (DEG), and calcium or zinc (Ca/Zn) stearate as a catalyst. These treatments depend on the chemicals that can affect human health and the ecosystem. The biodegradation treatment using bacterial and fungal species can consume the microplastic without disrupting the surrounding environment and biota. It includes recent findings on the biodegradation of microplastic under aerobic and anaerobic conditions. Thus, biodegradation can be considered the best option to degrade microplastic as green and sustainable technology.

Managing plastic waste disposal by assessing consumers' recycling behavior: the case of a densely populated developing country

The rapid increase in urbanization has given rise to the need of proper waste management. Within municipal waste, the plastic waste is a growing concern which is causing severe harm to our ecosystem. If ignored, this problem will have harmful effects on both human and wildlife. Therefore, this study aims to find out the factors that influence the recycling behavior patterns of consumers regarding plastic waste. The variables from the theory of planned behavior were adopted to study the behavior of consumers toward recycling plastic waste. The data was collected from 243 residents of Karachi-metropolitan city of Pakistan. The partial least square-structural equation modelling was applied to analyze the data. The findings of the current study reveal that different consumers' attributes and attitudes trigger different types of recycling behavior when it comes to waste disposal. Pressure from family and friends and perceived behavioral control trigger the behavior of reselling the waste plastic products while consumer's awareness of consequences and personal attitude toward proper waste disposal leads to reuse or donating that product to someone who can use that plastic product. The understanding of these consumer attributes may help to shape the behavioral outcomes in order to manage waste disposal. This study will be beneficial for business managers looking to improve reverse logistics as well as government/municipal policy makers and academics/researchers who are interested in a solution-oriented study.