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Options for closing the loop for plastic debris - Environmental analysis of beach clean-up and waste treatments
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Plastic debris (PD) is one of the biggest pollution problems in the marine environment. Nets, ropes, packaging, and pellets are the most common items that are spread around the world’s oceans causing an impact on wildlife and human health, and economic loss. Although mitigation is tantamount, the question remains for what can be done with the plastics that are already in the oceans. We conducted a literature review of research on debris and plastics waste management. Studies as shown that much of the collected marine debris goes to landfilling because it is little-known, diverse, salty, and too dirty for both incineration and recycling. Also, it showed that there is a strong focus on describing the environmental problems of marine and plastic debris, and that plastic debris is described in natural science terms that the waste management industry cannot use for determining suitable treatments. In order to better translate beach debris data into waste management data, we have collected beach debris from the Swedish West coast and conducted physical and chemical analyses for the characterization of the debris in waste management terms. Based on this data and the literature review, we have identified several recycling options for the PD. To identify environmental pros and cons with the different treatments, we conducted a life cycle assessment (LCA) comparing mechanical, feedstock recycling and energy recovery to establish an appropriate and practical approach towards closing the loop for PD. These treatment options were analysed in the context of two clean-up operations. The analyses suggest that mechanical treatments are not suitable for most plastics (due to they are fragmented, degraded and with a wide range of additives) whereas chemical treatments are suggested as a suitable solution. Feedstock recycling allows the production of raw material, as well as it may have fewer emissions, in comparison with combustion or landfilling which have higher emissions per tonne of PD. Finally, the LCA of two clean-up operations were performed, using the data obtained in the previous processes to see the big picture: observing the ecological benefits of removing this debris, and seeing whether that benefit is juxtaposed according to the recycling option. Although the environmental profits are difficult to quantify, the LCA results suggest that the clean-up process can have a positive impact with both mechanical and feedstock recycling, as long as the operation itself has low emissions (e.g. reducing transport emissions of the volunteers).
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... However, to produce fibers through extrusion from plastic waste, it must first be melted to produce pellets. Furthermore, plastics must be classified as one type to proceed with this process, and some plastics showed decreasing strength during this process [66]. PET bottles are made from similar grades of plastic; as a result, they are suitable for both the bottle manufacturing process and for reprocessing into fibers [9,66]. ...
... Furthermore, plastics must be classified as one type to proceed with this process, and some plastics showed decreasing strength during this process [66]. PET bottles are made from similar grades of plastic; as a result, they are suitable for both the bottle manufacturing process and for reprocessing into fibers [9,66]. However, to use other plastics, it is possible to minimize the reduction in the strength of recycled plastics by cutting them. ...
... process [66]. PET bottles are made from similar grades of plastic; as a result, they are suitable for both the bottle manufacturing process and for reprocessing into fibers [9,66]. ...
This study summarizes existing studies on plastic recycling to determine whether ocean plastics with high pollution degrees could be used for cement-based materials. In particular, the methods to recycle plastic waste, the effects of recycled plastic on the physical and mechanical properties of cement-based materials, and their effective usage were investigated. Workability, density, compressive strength, split tensile strength, and flexural strength of cement-based materials with recycled plastics were reviewed and divided into recycled aggregates and fibers. Based on the previous investigation, the direction of research necessary to recycle marine plastics is suggested. As the amount of recycled plastic aggregate increased, the mechanical strength of cement-based materials decreased. The recycled plastic aggregate lowered the density and increased porosity of the cement-based material. Meanwhile, recycled plastic fibers reduced the compressive strength but improved the tensile strength; to effectively improve tensile strength, a volume content of less than 1.5% should be added to prevent balling fibers. Furthermore, an appropriate aspect ratio should be determined based on the type of plastic to be used.
... Similarly, mechanical recycling of plastics is associated with material downgrading 15 . For example, polyethylene (PE) packaging is recycled for blowing moulding applications for lower-quality products 27 . ...
Carbon materials, such as paper, wood, plastic and textiles, play an important role in our everyday life, from clothes and packaging to infrastructure. However, the use of those materials follows a linear way. We take carbon resources, we make products, and we discharge them in a short amount of time, producing GHG emissions along its supply chain. From its extraction, manufacture and, unlike other materials, also at its end of life, releasing its embedded carbon into the ecosphere.
One approach to reduce emissions and resource extraction is to move towards a circular economy, by recirculating waste to produce new materials. However, today's material recycling process fall short, only a small fraction is recycled and often to a lower quality. As an alternative, this work shows that emphasizing carbon recovery, instead of material recovery, changes the perspective on carbon-containing waste flows.
Consequently, material flow analysis of the current carbon material system was set, illustrating that the system losses are greater than the carbon material produced. If those carbon losses are assumed to be released as CO2, they will equal 6% of the current GHG. The flow analysis also showed that there is enough carbon in the waste for producing synthetic materials and that carbon can help to reduce the emissions and decouple from fossil extraction.
This analysis also displayed that the carbon available in post-consumer waste consists of a mix of synthetic and natural carbon materials, together with heteroatoms such as oxygen, nitrogen, and chlorine. A potential way to recover all carbon is thermochemical recycling, which can break down materials into building blocks, similar to the chemicals employed in the petrochemical industry. As mixed waste comprises a wide variety of materials, the thermal conversion poses a variety of challenges ranging from the unknown product distribution to the fate of heteroatoms.
The thermochemical conversion of three different mixed wastes was tested in a pilot-scale reactor to understand the product distribution. The experimental results showed that the conversion yielded a mixture of gases and aromatics compounds, together with a high share of unconverted. While some of these products can be used directly, such as olefins and benzene, others require further recovery and processing. Another finding is that a higher conversion temperature helps to limit heteroatoms in the hydrocarbons. Increasing the temperature to 800°C reduced the Chlorine-content in aromatics under ppm levels, but Oxygen and Nitrogen content are higher than ppm level and that may affect the carbon recovery and may require further separation steps.
While thermochemical recycling has the potential to go towards a circular economy and reduce emissions, further efforts are required to tackle the different challenges to make thermochemical conversion a viable recycling method for mixed wastes.
This paper reports the state of art review for processing techniques used in recycling of thermoplastics polymers with different types of reinforcements, especially for additive manufacturing (AM) applications. In last two decades, some studies have reported use of primary (1°), secondary (2°), tertiary (3°) and quaternary (4°) ways to process polymeric materials from recycling view point. But hither to little has been reported on standardisation of 1°/2°/3°/4° routes in AM applications. The present study bridges the gaps for use of 1°/2°/3°/4° routes as an industrial processing standard with low cost AM technology (which have been presented as four case studies for field engineers).
Marine debris (MDs) produces a wide variety of negative environmental, economic, safety, health and cultural impacts. Most marine litter has a very low decomposition rate (plastics), leading to a gradual accumulation in the coastal and marine environment. Characterization of the MDs has been done in terms of their pollutant content: PAHs, ClBzs, ClPhs, BrPhs, PCDD/Fs and PCBs. The results show that MDs is not a very contaminated waste. Also, thermal decomposition of MDs materials has been studied in a thermobalance at different atmospheres and heating rates. Below 400–500 K, the atmosphere does not affect the thermal degradation of the mentioned waste. However, at temperatures between 500 and 800 K the presence of oxygen accelerates the decomposition. Also, a kinetic model is proposed for the combustion of the MDs, and the decomposition is compared with that of their main constituents, i.e., polyethylene (PE), polystyrene (PS), polypropylene (PP), nylon and polyethylene-terephthalate (PET).
Plastic pollution is ubiquitous throughout the marine environment, yet estimates of the global abundance and weight of floating plastics have lacked data, particularly from the Southern Hemisphere and remote regions. Here we report an estimate of the total number of plastic particles and their weight floating in the world’s oceans from 24 expeditions (2007–2013) across all five sub-tropical gyres, costal Australia, Bay of Bengal and the Mediterranean Sea conducting surface net tows (N5680) and visual survey transects of large plastic debris (N5891). Using an oceanographic model of floating debris dispersal calibrated by our data, and correcting for wind-driven vertical mixing, we estimate a minimum of 5.25 trillion particles weighing 268,940 tons. When comparing between four size classes, two microplastic ,4.75 mm and meso- and macroplastic .4.75 mm, a tremendous loss of microplastics is observed from the sea surface compared to expected rates of fragmentation, suggesting there are mechanisms at play that remove ,4.75 mm plastic particles from the ocean surface.
Anthropogenic litter is present in all marine habitats, from beaches to the most remote points in the oceans. On the seafloor, marine litter, particularly plastic, can accumulate in high densities with deleterious consequences for its inhabitants. Yet, because of the high cost involved with sampling the seafloor, no large-scale assessment of distribution patterns was available to date. Here, we present data on litter distribution and density collected during 588 video and trawl surveys across 32 sites in European waters. We found litter to be present in the deepest areas and at locations as remote from land as the Charlie-Gibbs Fracture Zone across the Mid-Atlantic Ridge. The highest litter density occurs in submarine canyons, whilst the lowest density can be found on continental shelves and on ocean ridges. Plastic was the most prevalent litter item found on the seafloor. Litter from fishing activities (derelict fishing lines and nets) was particularly common on seamounts, banks, mounds and ocean ridges. Our results highlight the extent of the problem and the need for action to prevent increasing accumulation of litter in marine environments.
Marine debris produces a wide variety of negative environmental, economic, safety, health and cultural impacts. Most marine litter has a very low decomposition rate (as plastics, which are the most abundant type of marine debris), leading to a gradual, but significant accumulation in the coastal and marine environment. Along that time, marine debris is a significant source of chemical contaminants to the marine environment. Once extracted from the water, incineration is the method most widely used to treat marine debris. Other treatment methods have been tested, but they still need some improvement and so far have only been used in some countries. Several extraction and collection programs have been carried out. However, as marine debris keep entering the sea, these programs result insufficient and the problem of marine debris will continue its increase. The present work addresses the environmental impact and social aspects of the marine debris, with a review of the state of the art in the treatments of this kind of waste, together with an estimation of the worldwide occurrence and characteristics.
This review article summarises the sources, occurrence, fate and effects of plastic waste in the marine environment. Due to its resistance to degradation, most plastic debris will persist in the environment for centuries and may be transported far from its source, including great distances out to sea. Land- and ocean-based sources are the major sources of plastic entering the environment, with domestic, industrial and fishing activities being the most important contributors. Ocean gyres are particular hotspots of plastic waste accumulation. Both macroplastics and microplastics pose a risk to organisms in the natural environment, for example, through ingestion or entanglement in the plastic. Many studies have investigated the potential uptake of hydrophobic contaminants, which can then bioaccumulate in the food chain, from plastic waste by organisms. To address the issue of plastic pollution in the marine environment, governments should first play an active role in addressing the issue of plastic waste by introducing legislation to control the sources of plastic debris and the use of plastic additives. In addition, plastics industries should take responsibility for the end-of-life of their products by introducing plastic recycling or upgrading programmes.
This chapter aims to provide an overview of the regulation and management instruments developed at international, regional and national levels to address marine litter problems, put forward the potential gaps in the existing management body and suggest solutions. While not covering the gamut of all relevant instruments, a number of existing instruments, including specific management measures contained therein, were profiled as illustration. The management measures illustrated are either on a mandatory or voluntary basis and provide a general, snapshot picture of the management framework of marine litter. They can be broadly divided into four categories: preventive, mitigating, removing and behavior-changing. The preventive and behavior-changing measures are particularly important in addressing marine litter at its root. The former schemes include source reduction, waste reuse and recycling, containing debris at points of entry into receiving waters and land-based management initiatives (e.g. restriction of the use of plastic bags, establishment of extended producer responsibility). The latter schemes aid people’s engagement in the other three types of measures, including education campaigns and activities raising awareness (e.g. Fishing for Litter). The potential gaps include limits of existing instruments in addressing plastic marine litter, deficiencies in the legislation and a lack of enforcement of regulations, poor cooperation among countries on marine litter issues and insufficient data on marine litter. To fill these gaps, recommendations are proposed, including establishment of a new international instrument targeted to the plastic marine litter problem, amending existing instruments to narrow exceptions and clarify enforcement standards, establishing national marine litter programe, enhancing participation and cooperation of states with regard to international/regional initiative, and devising measures to prevent marine litter from fishing vessels.
This chapter traces the history of marine litter research from anecdotal reports of entanglement and plastic ingestion in the 1960s to the current focus on microplastics and their role in the transfer of persistent organic pollutants to marine food webs. The reports in Science of large numbers of plastic pellets in the North Atlantic in the early 1970s stimulated research interest in plastic litter at sea, with papers reporting plastics on the seafloor and impacting a variety of marine animals. The focus then shifted to high concentrations of plastic litter in the North Pacific, where novel studies reported the dynamics of stranded beach litter, the factors influencing plastic ingestion by seabirds, and trends in fur seal entanglement. By the early 1980s, growing concern about the potential impacts of marine litter resulted in a series of meetings on marine debris. The first two international conferences held in Honolulu by the US National Marine Fisheries Service played a key role in setting the research agenda for the next decade. By the end of the 1980s, most impacts of marine litter were reasonably well understood, and attention shifted to seeking effective solutions to tackle the marine litter problem. Research was largely restricted to monitoring trends in litter to assess the effectiveness of mitigation measures, until the last decade, when concern about microplastics coupled with the discovery of alarming densities of small plastic particles in the North Pacific ‘garbage patch’ (and other mid-ocean gyres) stimulated the current wave of research. © 2015, Springer International Publishing. All Rights Reserved.
This paper analyses four strategies for managing the Mixed Municipal Solid Waste (MMSW) in terms of their environmental impacts and potential advantages by means of Life Cycle Assessment (LCA) methodology. To this aim, both a multi-input and a multi-output approach are applied to evaluate the effect of these perspectives on selected impact categories. The analyzed management options include direct landfilling with energy recovery (S-1), Mechanical-Biological Treatment (MBT) followed by Waste-to-Energy (WtE) conversion (S-2), a combination of an innovative MBT/MARSS (Material Advanced Recovery Sustainable Systems) process and landfill disposal (S-3), and finally a combination of the MBT/MARSS process with WtE conversion (S-4). The MARSS technology, developed within an European LIFE PLUS framework and currently implemented at pilot plant scale, is an innovative MBT plant having the main goal to yield a Renewable Refined Biomass Fuel (RRBF) to be used for combined heat and power production (CHP) under the regulations enforced for biomass-based plants instead of Waste-to-Energy systems, for increased environmental performance. The four scenarios are characterized by different resource investment for plant and infrastructure construction and different quantities of matter, heat and electricity recovery and recycling. Results, calculated per unit mass of waste treated and per unit exergy delivered, under both multi-input and multi-output LCA perspectives, point out improved performance for scenarios characterized by increased matter and energy recovery. Although none of the investigated scenarios is capable to provide the best performance in all the analyzed impact categories, the scenario S-4 shows the best LCA results in the human toxicity and freshwater eutrophication categories, i.e. the ones with highest impacts in all waste management processes.
Copyright © 2015 Elsevier Ltd. All rights reserved.
Plastic debris in the marine environment is widely documented, but the quantity of plastic entering the ocean from waste generated on land is unknown. By linking worldwide data on solid waste, population density, and economic status, we estimated the mass of land-based plastic waste entering the ocean. We calculate that 275 million metric tons (MT) of plastic waste was generated in 192 coastal countries in 2010, with 4.8 to 12.7 million MT entering the ocean. Population size and the quality of waste management systems largely determine which countries contribute the greatest mass of uncaptured waste available to become plastic marine debris. Without waste management infrastructure improvements, the cumulative quantity of plastic waste available to enter the ocean from land is predicted to increase by an order of magnitude by 2025.
Copyright © 2015, American Association for the Advancement of Science.
