Shredder machine for plastic recycling: A review paper

Plastic pollution has become a global concern due to poor plastic waste disposal management. As an alternative, independent recycling efforts are necessary. A Plastic shredder machine is a preliminary machine used to cut plastic waste into small pieces before turning it into useful products. The concept design of the shredder machine that is currently available is fairly similar. The shaft and blades are the critical components in the shredder machine that determines its performance. The geometry and orientation of the blades that were fitted into the single or double-shafts were found to directly affect the shredding performance. Therefore, this article aims to review the various geometry and orientations of the blades that give direct effect on the shredding performance, as well as identifying the research gaps related to the shredder machine for plastic waste materials

Plastic Packaging: A Study on Plastic Imports in Uganda

Plastic packaging is crucial in preserving the quality of products. It has become ubiquitous, and an inseparable part of daily life and the food industry due to its aesthetic attributes, strength, affordability and convenience of use. This has thus led to the increase in demand and imports of plastics in the country. However, plastic packaging alone accounts for 47% of global plastic waste amidst documented threats of plastic waste to the environment-water-food-health nexus. Several reports indicate that between 1994 and 2017, Uganda imported a total of 1.9 million tons of plastic in both raw and finished form compared to 117 million tons across Africa. Imports and use of plastics in Uganda have increased by six-fold within the last three years hence extrapolating the growing challenge for sustainable plastic imports, product packaging, and waste management. The objective of the review therefore was to explore the future trend and impact of plastic imports and packaging in Uganda by analyzing plastic imports and the associated waste. The study further reviews the challenges arising from the growing demand for plastic packaging and presents a discussion on the solutions and potential ways forward for win-win benefits. Several strides to curb the menace of plastic waste are presented, which are manly from the private sector and plastic recycling businesses. A conclusion is made that if these efforts are to meet the intended leaps of change, the government of Uganda has to support the private organisations through grants, space allocation for collection centers and media access across the country. Furthermore, stricter regulations on excess plastic importation have to be implemented by the government as the country develops locally grown solutions to plastic packaging and use.

Current Topics in Plastic Recycling

This chapter presents an overview of current trends in plastic recycling and focuses on specific topics of interest. Firstly, there are presented all methods used for plastic recycling, along with the advantages and disadvantages of each method. Extra attention is paid to chemical recycling and especially, pyrolysis (thermal and catalytic), which is an environmentally friendly method that results in the formation of value-added products. Emphasis is given on three case studies where there are difficulties as regards the recycling of the plastic part: polymeric blends, since the existence of mixed plastic wastes may be challenging for their recycling; plastics originating in multilayer packaging, since the multilayer packaging consists of various materials, including plastics, paper, and metals that may be an obstacle for the recycling of the plastic part; and brominated flame-retarded plastics from waste electric and electronic equipment (WEEE), since in this case safe handling is required in order to avoid environmental contamination and a pretreatment step before recycling may be of paramount importance. These three case studies along with the mentioned difficulties and suggestions in order to overcome them are presented here, with the aim of offering insights for future studies on the management of plastic materials.

Directed Evolution of an Efficient and Thermostable PET Depolymerase

The recent discovery of a hydrolytic enzyme, IsPETase, that can deconstruct poly(ethylene) terephthalate (PET), has sparked great interest in biocatalytic approaches to recycle plastics. Realisation of commercial utility will require the development of robust engineered enzymes that meet the demands of industrial processes. Although rationally engineered variants of PETases have been reported, enzymes that have been experimentally optimised through iterative rounds of directed evolution - the go-to method for engineering industrially useful biocatalysts – have not yet been described. Here, we report the development and implementation of an automated, high-throughput directed evolution platform for engineering polymer degrading enzymes. Evaluation of >13,000 IsPETase variants, applying catalytic activity at elevated temperatures as a primary selection pressure, afforded a HotPETase variant with 21 mutations that has a melting temperature of 82.5C and can therefore operate near or above the glass transition temperature of PET (60-70C). HotPETase can depolymerise semi-crystalline PET more rapidly than previously reported PETases and can selectively deconstruct the PET component of a laminated packaging multi-material. Structural characterisation of HotPETase reveals several interesting features that have emerged during evolution to improve thermotolerance and catalytic performance. Our study establishes laboratory evolution as a platform to engineer useful plastic degrading enzymes to underpin biocatalytic plastic recycling processes.

Resistance to Opportunities of Plastic Recycling

Plastics present a vast and pressing issue in modern society. Currently recycling efforts fall dangerously short of dealing with even a small percent of the millions of tons of plastic waste produced yearly across the globe. This article investigates resistance toward plastic recycling in three areas from both a contemporary and a historical context, highlighting the magnitude of the problem and the insufficient nature of current solutions. The three primary areas covered are the plastics problem from (1) a design perspective, (2) a material science perspective, and (3) a systems perspective. Solutions are proposed that emphasize a synergistic collaboration across disciplines and research modes. Ultimately, the conclusions point to a need for stronger engagement at the level of people (both consumers and decision makers) and reintegrating reused and recycled plastics into everyday life to build a solid foundation for success.

A New TOPSIS Approach Using Cosine Similarity Measures and Cubic Bipolar Fuzzy Information for Sustainable Plastic Recycling Process

A cubic bipolar fuzzy set (CBFS) is a robust paradigm to express bipolarity and vagueness in terms of bipolar fuzzy numbers and interval-valued bipolar fuzzy numbers. The abstraction of similarity measures (SMs) has a large number of applications in various fields. Therefore, in this study, taking the advantage of CBFSs, three cosine similarity measures for CBFSs are proposed successively by using cosine of the angle between two vectors, new distance measures, and cosine function. Some key properties of these similarity measures (SMs) are explored. Based on suggested SMs, the problem of bacteria recognition is analyzed and an important application is provided to exhibit the efficiency of proposed SMs for CBF information. Moreover, the TOPSIS approach based on cosine SMs is developed for multicriteria group decision-making (MCGDM) problems. An illustrative example about the selection of sustainable plastic recycling process is presented to discuss the efficiency of the suggested MCGDM technique.

Upcycling plastic waste through empirical implementation of large-scale 3D printing

<p>Plastic waste presents a real global challenge and a threat to health, environment and the global economy. While awareness of the devastating effects of plastic waste on the environment has increased, the production of plastic products is still on the rise. As a result, many countries do not prioritise waste plastic recycling or the export of plastic wastes to other countries for recycling. However, the products from recycled waste plastics are considered to be of low quality and uneconomical to produce on large scale, thus making individuals and corporations giving preference using plastics from virgin materials rather than producing products from recycled plastics. These is therefore a need to develop an effective process through the use of technology to upcycle plastic waste locally to produce products of higher value from waste plastic. The current research sought to investigate the potential of distributed upcycling to change the production and consumption of plastic products in future. To this end, the study sought to prepare high value design application for upcycling and investigated how they could be implemented through large-scale 3D printing in urban environments. To achieve this, the researcher collected plastic waste materials from Wellington in New Zealand to be used in the study experiments. The plastic waste materials were first cleaned, sorted and cut into small pieces using a granulator before being taken through thermal processes to dry them out and set the right temperatures to ensure consistency of the plastic waste extrusion before being taken through the extrusion process. 3D Printing was used to design and make various final products from the recycled plastic waste. Experimentation with different formulations of waste plastic led to production of a high-quality filament successfully achieving the study objectives. As such, upcycling plastic waste using 3D Printing technology provides a locally viable solution to making useful products in large scale as a model for future development.</p>

Upcycling plastic waste through empirical implementation of large-scale 3D printing

<p>Plastic waste presents a real global challenge and a threat to health, environment and the global economy. While awareness of the devastating effects of plastic waste on the environment has increased, the production of plastic products is still on the rise. As a result, many countries do not prioritise waste plastic recycling or the export of plastic wastes to other countries for recycling. However, the products from recycled waste plastics are considered to be of low quality and uneconomical to produce on large scale, thus making individuals and corporations giving preference using plastics from virgin materials rather than producing products from recycled plastics. These is therefore a need to develop an effective process through the use of technology to upcycle plastic waste locally to produce products of higher value from waste plastic. The current research sought to investigate the potential of distributed upcycling to change the production and consumption of plastic products in future. To this end, the study sought to prepare high value design application for upcycling and investigated how they could be implemented through large-scale 3D printing in urban environments. To achieve this, the researcher collected plastic waste materials from Wellington in New Zealand to be used in the study experiments. The plastic waste materials were first cleaned, sorted and cut into small pieces using a granulator before being taken through thermal processes to dry them out and set the right temperatures to ensure consistency of the plastic waste extrusion before being taken through the extrusion process. 3D Printing was used to design and make various final products from the recycled plastic waste. Experimentation with different formulations of waste plastic led to production of a high-quality filament successfully achieving the study objectives. As such, upcycling plastic waste using 3D Printing technology provides a locally viable solution to making useful products in large scale as a model for future development.</p>