Global Plastic Waste Research Articles

Modelling the global impact of China’s ban on plastic waste imports

China has long been the world’s leading plastic waste importer. However, in January 2018 the Chinese Government enacted a new policy to permanently ban the import of most plastic waste into the country. This raises an important question: what will the impact of this policy be both domestically and globally? It is argued that the answer to this question can in part be systematically revealed by employing three methods of analysis. (1) A combined multiregional input-output model with structural path analysis (SPA) to understand how consumption patterns domestically and globally drive China’s plastic waste imports. (2) An ecological network analysis to identify which region is the dominant controller of the global plastic waste trade network. Lastly, (3) a hypothetical extraction method to investigate the value-added change for China and the increased requirement of waste treatment capacity for other economies. The results indicate that the imported plastic waste was mainly driven by China’s domestic consumption of products containing recycled plastic. Given this demand, it is recommended that the Chinese Government undertake various actions to increase local plastic waste recycling to compensate for the loss of recycled plastic material since the import ban took place. China is a dominant controller, along with the US, the European Union and Germany of the global plastic waste trade network. At this stage it is not possible for other large economies to replace the role of China in the short term. China’s waste import ban caused a minor economic loss for China, however, it has resulted in the need for other economies to increase their waste treatment capacity. As well as increasing local plastic waste recycling, it is recommended the Chinese Government consider reopening imports for high quality recycled material and to seek global collaboration, which would not only ease the shortage of recycled plastic material but also buy time for other economies to build new waste treatment plants.

Structure of the global plastic waste trade network and the impact of China’s import Ban

Millions of tonnes (teragrams) of plastic waste are traded around the world every year, which plays an important role in partially substituting virgin plastics as a source of raw materials in plastic product manufacturing. In this paper, global plastic waste trade networks (GPWTNs) from 1988 to 2017 are established using the UN-Comtrade database. The spatiotemporal evolution of the GPWTNs is analyzed. Attention is given to the country ranks, inter- and intra-continental trade flows, and geo-visual communities in the GPWTNs. We also evaluate the direct and indirect impacts of China’s plastic waste import ban on the GPWTNs. The results show that the GPWTNs have small-world and scale-free properties and a core-periphery structure. The geography of the plastic waste trade is structured by Asia as the dominant importer and North America and Europe as the largest sources of plastic waste. China is the unrivaled colossus in the global plastic waste trade. After China’s import ban, the plastic waste trade flows have been largely redirected to Southeast Asian countries. Compared with import countries, export countries are more important for the robustness of GPWTNs. Clearly, developed countries will not announce bans on plastic waste exports; these countries have strong motivation to continue to shift plastic waste to poorer countries. However, the import bans from developing countries will compel developed countries to build new disposal facilities and deal with their plastic waste domestically.

Utilization of waste plastic oil in diesel engines: a review

Disposal of waste plastic accumulated in landfills is critical from the environmental perspective. The energy embodied in waste plastic could be recovered by catalytic pyrolysis as waste plastic oil (WPO) which could be recycled as a fuel for diesel engines. This method presents a sustainable solution for (a) waste plastic management as the gap between global plastic production and waste plastic generation keeps widening, (b) replacing diesel partially or wholly which is currently extracted from fast depleting fossil crude oil. The present work attempts to bring together all the investigations pertaining to WPO usage either (a) as a neat fuel or (b) as a blend component with diesel or (c) with an oxygenated additive till date in diesel engines and reviews the engine’s performance, emission and combustion characteristics. Majority of the works utilised WPO extracted from mixed waste plastic as a feedstock using a laboratory scale batch reactor via catalytic pyrolysis. Silica, Alumina, ZSM-5 and Kaolin were used as catalysts. This method often yielded up to 80% of liquid WPO. This oil had a slightly lower cetane number than fossil diesel and hence produced longer ignition delays and higher heat releases during premixed combustion phasing. NOx emissions were higher with WPO which is addressed by modifying the injection timing or by means of EGR. Contrary to popular belief, smoke emissions are mostly lower with WPO and could be brought down further to Euro levels by the use of oxygenated additives. In summary, WPO was found to run smoothly in diesel engines and more work is necessary to study the PM characterisation and long-term durability of the engine when fueled with this oil.

Future scenarios of global plastic waste generation and disposal

The accumulation of mismanaged plastic waste (MPW) in the environment is a global growing concern. Knowing with precision where litter is generated is important to target priority areas for the implementation of mitigation policies. In this study, using country-level data on waste management combined with high-resolution distributions and long-term projections of population and the gross domestic product (GDP), we present projections of global MPW generation at ~1 km resolution from now to 2060. We estimated between 60 and 99 million metric tonnes (Mt) of MPW were produced globally in 2015. In a business-as-usual scenario, this figure could triple to 155–265 Mt y−1 by 2060. The future MPW load will continue to be disproportionately high in African and Asian continents even in the future years. However, we show that this growth in plastic waste can be reduced if developing economies significantly invest in waste management infrastructures as their GDP grows in the future and if efforts are made internationally to reduce the fraction of plastic in municipal solid waste. Using our projections, we also demonstrate that the majority of MPW (91%) are transported via watersheds larger than 100 km2 suggesting that rivers are major pathways for plastic litter to the ocean.

Plastic pollution and potential solutions.

Plastic pollution and potential solutions.

The Chinese import ban and its impact on global plastic waste trade.

The rapid growth of the use and disposal of plastic materials has proved to be a challenge for solid waste management systems with impacts on our environment and ocean. While recycling and the circular economy have been touted as potential solutions, upward of half of the plastic waste intended for recycling has been exported to hundreds of countries around the world. China, which has imported a cumulative 45% of plastic waste since 1992, recently implemented a new policy banning the importation of most plastic waste, begging the question of where the plastic waste will go now. We use commodity trade data for mass and value, region, and income level to illustrate that higher-income countries in the Organization for Economic Cooperation have been exporting plastic waste (70% in 2016) to lower-income countries in the East Asia and Pacific for decades. An estimated 111 million metric tons of plastic waste will be displaced with the new Chinese policy by 2030. As 89% of historical exports consist of polymer groups often used in single-use plastic food packaging (polyethylene, polypropylene, and polyethylene terephthalate), bold global ideas and actions for reducing quantities of nonrecyclable materials, redesigning products, and funding domestic plastic waste management are needed.

Combined influence of injection timing and EGR on combustion, performance and emissions of DI diesel engine fueled with neat waste plastic oil

Disposal of waste plastic accumulated in landfills is critical from the environmental perspective. The energy embodied in waste plastic could be recovered by catalytic pyrolysis as waste plastic oil (WPO) and could be recycled as a fuel for diesel engines. This method presents a sustainable solution for waste plastic management as the gap between global plastic production and waste plastic generation keeps widening. The present study investigates the combined influence of EGR and injection timing on the combustion, performance and emission characteristics of a DI diesel engine fueled with neat WPO. Experiments were conducted at three injection timings (21°, 23° and 25°CA bTDC) and EGR rates (10, 20 and 30%) at the engine’s rated power output. When compared to diesel, the combustion event occurred closer to the TDC when the injection timing is delayed from 25°CA bTDC to 21°CA bTDC. The peak in-cylinder pressures and HRRs dropped gradually as the injection timing was delayed from 25°CA bTDC to 21°CA bTDC at all EGR rates. The engine delivered diesel-like fuel consumption with 5.1% higher brake thermal efficiency. NOx decreased up to 52.4% under 30% EGR when WPO was injected lately 21°CA bTDC. Smoke density remained lower by 46% and 9.5% for 10% and 20% EGR rates respectively for WPO only at early injection timing of 25°CA bTDC. HC and CO emissions stayed lower at early injection timing of 25°CA bTDC under 10% EGR. WPO injected at the advanced injection timing of 25°CA bTDC and low EGR rate of 10% was found to simultaneously reduce smoke and NOx by 46% and 38% respectively.

Isolation and Characterization of Bacteria that Produce Polyhydroxybutyrate Depolymerases.

Isolation of environmental bacterial strains with diverse metabolic properties such as antibiotic production, sulfide oxidation, and the ability to use different nutrient sources is a common undergraduate lab experience. This article describes a useful protocol for the detection and isolation of bacteria that can degrade the common carbon storage biopolymer poly (3-hydroxybutyrate) (PHB). The procedure utilizes a low nutrient media supplemented with insoluble PHB that allows for the easy, visible detection of strains that produce extracellular PHB degrading enzymes. This method can be used to determine the percent of culturable bacteria from various environments that can degrade PHB. Further, PHB degrading exoenzyme activity can be monitored from pure cultures by: (1) Growing cells in broth, (2) inducing with PHB, and (3) measuring activity of supernatant with a UV/Vis spectrophotometer. The enzymatic breakdown of PHB presents an opportunity to expose students to the concept of using biodegradable plastics as a solution to the global plastic waste problem.

A global inventory of small floating plastic debris

Microplastic debris floating at the ocean surface can harm marine life. Understanding the severity of this harm requires knowledge of plastic abundance and distributions. Dozens of expeditions measuring microplastics have been carried out since the 1970s, but they have primarily focused on the North Atlantic and North Pacific accumulation zones, with much sparser coverage elsewhere. Here, we use the largest dataset of microplastic measurements assembled to date to assess the confidence we can have in global estimates of microplastic abundance and mass. We use a rigorous statistical framework to standardize a global dataset of plastic marine debris measured using surface-trawling plankton nets and coupled this with three different ocean circulation models to spatially interpolate the observations. Our estimates show that the accumulated number of microplastic particles in 2014 ranges from 15 to 51 trillion particles, weighing between 93 and 236 thousand metric tons, which is only approximately 1% of global plastic waste estimated to enter the ocean in the year 2010. These estimates are larger than previous global estimates, but vary widely because the scarcity of data in most of the world ocean, differences in model formulations, and fundamental knowledge gaps in the sources, transformations and fates of microplastics in the ocean.