**7. Controlling elements for plastic recycling**

Achieving a transition to a circular economy of plastics depends on the costeffective and efficient reuse and recycling of plastics at large scales. A combination of end-of-life management approaches for plastics can reduce use, reuse, and repair, leading to a decreased energy and materials [74]. Recycling is a vital part of industrial ecology that can reduce environmental impacts and resource depletion. PET and HDPE are widely recycled when used in specific categories such as plastic bottles. However, this is an exception and is not seen for other plastic categories (**Table 1**).

**Figure 9.**

*Schematic diagram showing process steps for pyrolysis and other thermo-catalytic processing of plastic waste.*

This could be due to the cost structure of recycled plastics, the challenges of sorting mixed plastics, and the variability of the cost of virgin plastics. Many post-consumer plastics may have to be converted to other products, and they are recycling a limited number of times. The controlling factors for recycling plastics include the effectiveness of collection and segregation of mixed materials, collection and storage of recyclables, geographical location of recycling facilities concerning the processing markets, and volume of the recyclable materials collected for the region.

The incompatible nature of most plastics due to their inherent immiscibility at a molecular level is one of the significant challenges for producing high-quality resins. For example, a small quantity of PVC in PET recycling degrades the quality of the recycled material. Hence, mixing recycled plastics with virgin plastics could reduce some of the attributes of the virgin materials, and hence, the recycled plastics are mainly used for non-critical applications. Hence, post-consumer recycling involves multiple steps: collection, sorting, washing, size reduction, and separation to minimize contamination by incompatible plastics [7]. Plastic additives such as plasticizers, color, and flame retardants used in manufacturing some plastics complicate the recycling process and present risks to human health and ecology.

#### **8. Infrastructure development and access**

The successful implementation of the plastic circular economy will require sufficient infrastructure to process-collected material. Due to the current lack of processing capacity, there is a need to modify or modernize existing recycling infrastructure [75].

#### **8.1 Availability of suitable feedstock**

The effective implementation of a CE for plastics is dependent upon the availability of feedstock, adequate recycling infrastructure, and technologies that can

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

convert nonrecycled plastics to fuel or chemical feedstock. In 2016, only 16% of the inflow of polymers was collected for recycling, 40% were sent to landfills, and 25% incinerated. Recently, European countries have increased efforts to improve recycling rates. In 2018, 29.1 million tons of post-consumer plastic waste were collected in Europe. While less than a third of this was recycled, it represented a doubling of the quantity recycled and reduced plastic waste exports outside the European Union (EU) by 39% compared to what was recycled in 2006 [55].

The degree to which plastic recycling can be increased is limited by the availability of suitable feedstock. The ability to increase plastic recycling rates is inextricably linked to the collection rates, quality of the collected plastic, and the availability of recycling technologies to manage the post-use waste stream. Mechanical, or closed-loop processes are limited by the types of plastics that can be processed, resulting in sub-optimal yields. Plastic bottles are a highly desirable product for recyclers, but just about a third find their way into a recycling bin [76].

Chemical recycling enables the processing of mixed waste streams. However, just like mechanical recycling, advanced recycling facilities require a dependable flow of materials (feedstock) that fit the technology process [10]. Some chemical recyclers currently in operation rely on high-quality material, such as postconsumer bottles or recycled PET (rPET) polyethylene terephthalate flake as a feedstock to get a better quality of output. However, there is a concern in the recycling community that the new technologies are in danger of stripping the mechanical recycling industry of its much needed and increasingly scarce feedstock of high-quality post-consumer plastic waste. Because of the cost and challenge of sorting and separating, most chemical recyclers are not targeting low-quality waste but rather the same waste streams that would typically be used in mechanical recycling [10].
