May 13, 2020

How to Eliminate Microplastics Pollution?: Decision-Making Considerations on Feeding Plastic Waste into Circular Carbon Economy

Serpil Guran

Introduction

Plastics play a significant role in our lives. They are in most of the items we use and dispose daily. Both increased generation of plastic waste and inefficient disposal approaches are causing plastic waste leakage into the environment. Unrecycled plastics end up in landfills and dumpsites, are incinerated, or leak into the waterways and oceans where they will remain hundreds or even thousands of years. It is reported that the amount of plastics in the marine litter is between 60 and 80 percent based on the locations. This highlights that plastics contamination is a major environmental problem.Presence of large plastic items may appear as an entanglement threat, in addition to smaller plastics especially microplastics, which can be ingested by marine organisms. Environmental and health impacts of microplastics have been drawing increased attention since the early seventies. The presence of small plastic fragments in the environment was originally reported in the early seventies and the term microplastic was first used in research in 2004. The National Oceanic and Atmospheric Administration (NOAA) defines microplastics as plastic fragments smaller than 5 mm. Microplastic pollution is caused by numerous sources. While some microplastics are sourced by components of manufactured items such as cosmetics and other personal care products and the breakdown of synthetic fibers, larger amount of other microplastics enter the environment through fragmentation and degradation of larger plastic products from exposure to the UV light, freezing, wind wave action, and abrasion. Because plastic materials are generally manufactured to be durable goods, they remain in the environment for long time regardless of their origin, and their degradation may take decades especially in the marine environment.

Presence of microplastics in the environment could represent significant exposure risks for marine habitats in the oceans, land contamination, and resulting human exposure. Additives in plastics generally increase their functionality and because they are not bound to the polymer structure, they can leach out of plastics. Endocrine disruption causing phthalates, triclosan, polybrominated diphenyl ethers, and alkylphenols are known additives as plasticizers, antimicrobial, flame retardants, and antioxidant, respectively. Contaminants in the environment such as persistent organic pollutants (POPs) can be absorbed and transferred by microplastics because they have a high surface area to volume ratio and hydrophobicity. Contaminants such as bisphenol A (BPA), phthalates, organochlorine pesticides, cadmium, chromium, lead, and polyaromathic hydrocarbons that may cause cancer, renal toxicity, neurotoxicity, and endocrine disruption may also be present in the original plastic material.

Human exposure can occur through consumption of contaminated food and beverages, through plumbing, and airborne microplastics. Numerous studies described the presence of ingested microplastics in marine animals including fish and mussels. Ingestion may occur either direct uptake or through trophic transfer from consumption of prey. Some microplastics appeared in the digestive track of the species and some of them appeared to be in the muscle of the fish. Ingested polymers by marine animals included polystyrene, polyamide, polyethylene, polypropylene, polyester, nylon, polyethylene terephthalate, and polyurethane. Research states that in addition to ingesting microplastics through seafood, human exposure to microplastics may occur through ingesting microplastics-contaminated fresh water and drinking water, beer, and sea salt. In addition, research stated that microplastic contamination is possible in urban areas. If environmental contamination further increases resulting in increased plastic waste leakage, more up-to-date and reliable data is needed on the level of microplastic exposure and consequential effects.

Current Recycling of Plastics

Currently, the production, consumption, and disposal of plastics not only harms the environment, but also creates economic problems because most current approaches do not support closed-loop, low-carbon processes. Table 1 shows that plastic recycling is around 9 percent. 

Table 1. U.S. Plastic Waste Generation and Disposal Profile (Adapted from USEPA 2018) 

Waste Material
Weight Generated Metric Tons (Mt) Weight Recycled Mt Weight Incinerated for Energy Mt Weight Landfilled Mt Recycled % Incinerated % Landfilled %
Plastics
34.50
3.14
5.35
26.01
9.1
15.5
75.4

The recycling rates are low in the United States because participation is voluntary and there are no attractive incentives to encourage plastics recycling. In addition, in most locations, recycling is practiced as “single-stream recycling,” which increases plastic waste contamination. Further, additives make these plastics unattractive and economically unfeasible for recycling. Because fossil-based virgin plastic feedstocks are abundant and prices are low, they outcompete recycled plastics. There is a critical need for mechanisms in place to ensure and encourage manufacturers to use recycled plastic content in their products. If the plastic wastes are not recycled, they certainly will leave the economy. We manufacture it, use it, and throw it away (see figure 1a, 1b). The linear economy pathway of material movement is rooted in exponentially increasing resource consumption, excessive energy use, erosion of ecosystems including climate change, and massive amount of waste generation. As urbanization increases, the global solid waste problem and, consequently, the plastic waste problem are also expected to expand if we do not minimize current waste generation and still continue to utilize current linear waste disposal practices with inefficient recycling pathways.

Figure 1a. Linear Economy Resource Management Approach

Figure 1a. Linear Economy Resource Management Approach

Figure 1b. Linear Economy Resource Management with Recycling Approach

Figure 1b. Linear Economy Resource Management with Recycling Approach

Circular Carbon Economy and Resource Management Approach

Emerging circular carbon economy concept refers to an “economic system based on reuse of products and raw materials and restorative capacity of natural resources.” It also attempts to minimize value destruction in the overall system and to maximize value creation. Circular economy can be an effective pathway for lower-carbon economy in mitigating climate change within the efficient circular economy understanding. Therefore, promoting combined understanding of circularity and lower-carbon economy as “circular carbon economy” and transforming linear make-it /use-it/dispose-it pathway to circular resource recovery pathway can provide better results. Circularity approach should also redefine waste as a “resource” and feeding things back into the economy efficiently (see figure 2).

Figure 2. Closing the Loop for Resource Recovery

Figure 2. Closing the Loop for Resource Recovery

Decision-Making Options to Accelerate Integration of Plastic Waste into Circular Carbon Economy

To date, the inefficient integration of pre- and post-consumer plastic waste into the economy mainly was caused by economic reasons. Because the fossil-based virgin plastics are so cheap and abundant, the plastics industry has chosen to utilize virgin feedstocks instead of recycled ones. Further, because the plastics have dyes and additives and/or other contamination caused by either inefficient collection or packaging waste, reutilizing of plastics was not preferred by the industry.

In addition, greenhouse gas (GHG) emissions inventories generally report that globally, emissions related to waste management matters may not be as high as other GHG emitting sources––i.e. electricity generation from fossil fuel combustion or transportation fuels may create understanding that innovative approaches in the waste management sector may not contribute to climate change mitigation efforts substantially. European greenhouse emission statistics report that the waste sector contributed to approximately 3 percent of the total global GHG emissions in 2016. Similarly, the U.S. waste-related GHG emissions are reported by USEPA as about 2 percent of total emissions. These figures grossly underestimate the potential contribution of improved waste and resource management’s to GHG mitigation. This is also similar with the plastic waste disposal case. As mentioned, researchers estimated plastics End-of-Life (EoL) GHG emission contribution at 9 percent as compared to other stages of plastics production. However, with improvement in the recycling portion of the EoL scenario, they determined further substantial reductions in GHG emissions. In addition, if landfilling and incinerating portions of plastics are also reintegrated back into the economy in an innovative way, benefits would even be higher. Especially, while recovering chemical intermediates from plastic waste via gasification or pyrolysis, recovering process energy from the system would even reduce the GHG emissions further. Therefore, current waste management policies including plastic waste portion, which are still not driven by climate concerns, should be reevaluated. Research states that the potential contribution of waste prevention and management to GHG abatement could be far greater than the total reported emissions under the waste parts of the inventories. The Global Waste Management Outlook (GWMO) stated that potential impact of improved waste and resource management on reducing GHG emissions could be as high as 15 to 20 percent.

In order to integrate plastic wastes into the circular carbon economy, identifying barriers and near-mid- and long-term planning is essential. Barriers and challenges in achieving circular approach are summarized in Table 2. 

Table 2. Circular Resource and Carbon Management Challenges (Adopted from Ritzen & Sandstrom and revised) 

Economic- Cost (up-front investment, risks)
Structural- Lack of understanding and participation businesses, consumers, and decision makers)
Operational- Complex international production and consumption supply chains
Knowledge and Behavior- Need for knowledge and capacity for implementation. Need for education.
Environmental Assessment
Need for Regulations
 
Assessing financial benefits of circular economy
Achieving exchange of information
Redefining the infrastructure
Perception of sustainability
Correct Life Cycle Assessment (LCA) of circular approaches
Lack of standards, monitoring, and reporting
 
Assessing financial profitability
Defining responsibility distribution
Strong supply chain
Behavior change
     

Integration Planning

It is essential to create realistic short-, mid-, and long-term plans when dealing with environmental and economic matters that involve many stakeholders including public, business, and governmental decision makers. Setting goals, panning and subsequent decision-making, and monitoring progress processes should be based on reliable data, science, and innovation. Plans, decisions, set targets, and results should always be transparently communicated with the stakeholders. In addition, comprehensive outreach and education should be part of the planning.

The steps of the planning are as follows:

  • Short-term planning
    • Engage decision and policy makers
    • Avoid contamination in the waste streams
    • Improve collection and sorting
    • Enable secondary markets
    • Innovative thinking to reduce the leakage of plastics into the natural systems
  • Mid- and long-term planning:
    • Innovative thinking in creation of after-use plastics economy
    • Investment on better packaging
    • Policies and intervention for decoupling plastics production from fossil feedstocks
    •  Research and development

Conclusions

Transformation of inefficient linear plastic waste disposal practices and into efficient circular carbon systems to treat plastic waste as a resource involves critical decision-making. Integrating waste into circular carbon economy requires efficient circular carbon systems that can transform current linear make-it /use-it/dispose-it pathway to circular resource recovery pathway and can also provide climate change mitigation options. This transformation, if planned thoroughly, would create economically feasible, socially acceptable and environmentally sustainable solutions including reducing GHG emissions. It is essential to set realistic short-, mid-, and long-term targets and develop short-, mid-, and long-term plans when dealing with environmental matters that involve many stakeholders including public, business and governmental decision makers. 

    Serpil Guran

    Serpil Guran is the Director of the Rutgers EcoComplex. Her responsibilities include management of the EcoComplex operations, programs, business incubator and facilities, as well as providing vision and leadership in establishing the EcoComplex as a nationally recognized center for the commercialization of environmental and alternative energy technologies.


    Dr. Guran is trained on thermochemical conversion (pyrolysis and gasification) of sustainable biomass and waste materials for production of fuels and chemicals and she specializes in research, development and assessment of sustainable biofuels, innovative waste recycling technologies, and life cycle analysis of clean energy, alternative fuel production and sustainable food systems. Currently, she is working on Circular Carbon Systems, Food-Energy-Water Nexus and Waste synergy by promoting integration of organic and plastic waste into development of circular carbon economy with the goal of mitigating climate change and economic sustainability and social justice.