**1. Introduction**

Plastics are chemical success stories of the past 100 years that have touched every aspect of modern life. However, their success has a huge downside. Today more than 40 kg of plastic waste per person is produced each year globally. In 2018, the total amount of municipal solid waste (MSW) was 292.4 million tons, which is 2.2 kg/per capita per day (**Figure 1a**). This is a 40% increase from the 1990 waste generation. Although 23% of this waste is recycled, there is considerable variability in the type of waste [1]. Solid waste management conducted by local municipalities is a global challenge requiring aggressive attention. Poorly managed waste flows from terrestrial and air-born sources contaminate oceans and other water bodies.

#### **Figure 1.**

*(a) Total municipal solid waste generation by material in 2018 (total 262 million tons) (b) generation trend of plastic waste in the United States between 1960 and 2018, showing (c) recycling and composting rates as a percentage of generation (Source: US EPA, 2018).*

Flooding from clogged drains, air pollution emissions from burning, and contaminated urban areas provide significant input to this global dispersal of plastic waste. The complexity of solid waste management is a combined effect of social, environmental, and economic factors contributing to a multi-dimensional challenge demanding solutions. Inadequate solid waste management practices contribute to environmental problems in treating ecosystems, impacts of human health, and undesirable socioeconomics.

### **2. Current global plastics problem**

Plastic-related waste has increased by two orders of magnitude in the past halfcentury [2]. Paper and paperboard recycling is currently 66.5%, whereas plastic recycling was estimated at 4.4% in 2018. Some 5 million tons of plastic particles derived from the 300 million tons of annual global virgin plastic production are transported by rivers and deposited in the oceans. Mechanical degradation of macro size plastics leads to the formation of a large volume of microplastics that when combined with manufactured microbeads from personal care products lead to harmful conditions in aquatic ecosystems. The raw material for these virgin plastic resins is derived from petroleum. Its short use-life and high durability in the environment translates into an environmental lifetime exceeding hundreds of years underscoring plastic disposal/reuse as a significant environmental concern [3–6]. Although almost all commodity plastics carry the recycling symbol (**Table 1**), plastic recycling in the United States is crude, energy-intensive with recycled materials characterized by lower qualities than virgin plastic.

*Are Reliable and Emerging Technologies Available for Plastic Recycling in a Circular… DOI: http://dx.doi.org/10.5772/intechopen.101350*

*Source for recycling rates ref. [1].*

#### **Table 1.**

*Types of plastic resin and resin identification codes (RIC).*

A large portion of plastic products is used to make short-lived products such as packaging discarded after a single use [7]. European reports indicate that 70% of marine plastic litter is caused by single-use plastics [8]. Recycling is one of the sustainable ways to reduce the impacts of plastics and product reuse and energy recovery as fuel.

#### **3. Plastic economy**

Traditional plastic production is based on fossil feedstocks, where over 90% of currently manufactured plastics is derived from virgin fossil feedstocks with a huge carbon impact. Plastic production has been growing at an average of 40% in the past 50 years, surging from 15 M tons in 1964 to over 320 M tons in 2018, as plastic use increased in every application. Plastic packaging is one of the main applications of plastic use, representing 26% of the total volume of plastic use. Plastic packaging

has many economic benefits ranging from protecting products during shipping, preserving and reducing food waste, and reducing fuel consumption for transport due to lightweight. However, 95% of plastic packaging and 90% of total plastics are not recycled, because of which an estimated over 400 billion is lost to the economy annually [9].

Although universal recycling symbols were introduced 45 years ago, only a small fraction of plastics are recycled. Successful recycling requires reliable and efficient post-consumer collections for similar products, consistent consumer demand, and economical remanufacturing. These factors are interdependent, since the economy of scale requires effective collocation of used materials that are not too contaminated, located close to recycling sites, and require a community that is committed to sorting properly based on Resin Identification Codes (RIC; **Table 1**). However, there are too many chemical variations of plastic products distributed among too few categories. Packaging represents 26% of the total volume of plastics used and out of the single-use plastic, mainly packaging materials, which have short first-use cycle one third escape collection system [9]. Of the different resins listed, polyethylene terephthalate (PET) and high-density polyethylene (HDPE), codes 1 and 2, are the more easily recycled plastics. The cost of plastic waste on oceans, clogging urban infrastructure, in addition to greenhouse gas emission during manufacturing, was estimated to exceed USD 40 billion [10].

Sustainable solid waste management requires improved collection infrastructure that includes the separation at the source, policies that encourage reuse/recycling, and supporting recycling [11]. The cost of recycling depends on the market, volume, required sorting, and decontamination of the feedstock. The flow of recycled plastic materials makes it uneconomical to justify separating low-volume streams. Many promising technologies emerging in the market offer opportunities to recover the value of some low-volume recycle streams. Optical and robotic sorting techniques along with digital watermarks are expected to increase the efficiency of sorting. Further investigative research is required to determine how to retrofit existing facilities to include new sorting technologies optimally.

#### **4. Current plastic linear value chain economy**

Plastics have been used in many applications, and their uses follow a linear economy, take-make-waste model. The fraction of global recycled plastics is low; 30% in Europe, 25% in China, and 9% in the United States. The current plastic economy is best understood as a "linear" model of value creation where the product lifecycle begins with extraction and ends with landfill disposal or release to the environment. About 4% of the world's petroleum product is used as plastic feedstock and a similar amount is used for processing products and transporting them. The raw materials are extracted and transformed into products. Generally, at the end of their use phase, the items are environmentally mismanaged in the disposal. Value is created in this economic system by producing and selling as many products derived from virgin polymeric materials as possible. The linear economic model has been in practice since the industrial revolution, has achieved economic growth, and has improved the standard of living. The model does not consider the natural depletion of resources or the disposition of the products after use, which often is landfilling, incineration, or other means of release to the environment, nor the value of the disposed of material for recycling or reuse (**Figure 2**). The linear plastic economy has proven unsustainable for its resource consumption and environmental and human health impacts.

*Are Reliable and Emerging Technologies Available for Plastic Recycling in a Circular… DOI: http://dx.doi.org/10.5772/intechopen.101350*

**Figure 2.** *Schematic representation of linear economy of plastic.*

The negative influences of the linear economic model of plastics, including the depletion of nonrenewable resources, climate change, and severe ecological impact, leave a significant footprint [1, 9]. The high reliance on an extracted virgin resource subject to high price fluctuations, the need for an increase in trade, and the geopolitical interconnectedness for raw material, and end-of-life disposal are major challenges in a linear economy. As the population and welfare of emerging economies have grown over the past few decades, the number of middle-class consumers has also been increasing. This, in turn, resulted in an increased demand for newer products and a shortened product lifespan that accelerated the disposal of more plastic waste. The move on to a sustainable economy can be achieved through the concept of the circular economic (CE) model that incorporates strategies for continuously reuse of material and resources [11]. Whereas recycling techniques like energy recovery through incineration generate air pollution, CE of plastics economy involves waste recovery using a range of recycling techniques to minimize plastic waste disposal by converting it to valuable products.
