Regular plastic has a life-cycle. It is extracted and refined first, and then manufactured into products, used, at last becomes waste. This is the end of first life. But what is waste to some markets is a resource to others, creating a number of alternative channels down which the plastic continues to flow. In-house plastic scrap is the off-cuts, bits and ends left in a material production facility or manufacturing plant when the usable material or product is shipped out. Almost 100% of in-house plastic scrap is recycled, meaning that it goes back into the primary production loop.
To reuse it, it must be collected (not always easy), identified, separated, decontaminated, chopped and processed and more. Despite these difficulties, plastic recycling can be economic, both in cash and energy terms. In the Hague, there are quite few plastic manufacture companies. In this paper, we put our perspective not only in the hague, we also looking for manufacturing process in the other city of Netherland, like Rotterdam, Utrecht and region, with a focus on household plastics.
At the moment, there are different ways of collecting the plastics. In The Hague plastics, cans and carton drink packaging are collected together in households. Civilians are asked to collect these three together and dispose them in special containers, spread throughout the city. Most of these plastics are recycled, but unfortunately it is not competetive enough with newly produced plastics.
Wildenberg Recycling B.V. has introduced a unique way of collecting plastics and making sure they are high quality and so be able to compete with newly produced plastics. Starting at company-level, they've organized a competition for companies to encourage them to sort their plastics better. The better the plastics are sorted at the source, the higher the quality is to resell it to factories. Every year one company is awarded a trophy for being the best 'plastic recycler'. More information can be found at http://wisselbeker.nl/.
Plastic is a non-biodegradable material which currently is used in everyday product. Due to its properties related to its long duration and as it does not break down naturally, plastic waste is the cause of many environmental negative impacts. The use of biodegradable polymers is growing, which is a good development. This paper, however, will focus on the reuse of those non-biodegradable plastics that are already in the loop and explore possibilities on how to keep them in the recycling process.
The following figure depicts the processes related to recycling plastic and which will be described below:
After the collection process, the first stepconsists of sorting of the different types of plastic by their properties, such as their type of resin or colour. Once this distinction has been made, the following classification is based on the label located at the products’ button which usually refers to resin identification code (RIC). As a result, different batches of plastic products are formed thanks to specific machines able to scan all the products in a considerable speed and allocate then at the beginning of the following process: shredding. Besides, it is essential to take into account that at the same type the possible contamination that the plastics could have is eliminated.
Getting the different plastics in tiny chunks or pieces separated into different categories is the goal pursued in this stage and whose efficacy will influence the rest of the processes. In addition to the shredding process, a process of cleaning is needed so that dirty and remaining contamination is definitely removed. In order to do it, specific detergents are using depending of the type of plastic is being processed. At the end of this stage, the clean plastic is dry.
At this point the melting process takes place, giving two possible alternatives: melting down the pieces of plastic and moulding them into new shapes or melting down and processing the plastic into granules. Both alternatives imply using different maximum temperatures depending on the type of plastic concerning their specific properties. Finally, the plastic pieces suffer a compression stage where their size is decreased to reach a tiny pellet size known as nurdle.
Once all these processes described have been completed the new plastic material achieved can be given different purposes. However, it is important to remark that in the majority of the cases the recycled plastic is hardly used to the original functions it used to have. Instead, the last form of pellet allows manufacturing companies to redesign and made a wide variety of different products using the recycle plastic in combination with virgin ones.
The most common types of recycle plastics: Polyethylene Terephthalate, High Density Polyethylene, Polyvinyl Chloride, Low Density Polyethylene. One recent use of recycling plastic has taken place recently in The Netherlands and is complete novel application. The Dutch construction firm VolkerWesselsis has developed a plastic road surfacing, which is in a future would be able to compete with the current and typical asphalt.
Furthermore, 90 of the 850 pedestrian and cyclists’ bridges in Rotterdam have been replaced with newfangled plastic bridges and the replacement plans of the old ones are oriented in this line.
After processing these collections, they become recycled material and ready to be refabricated. It can be used to make almost all kinds of plastic products, like bottles and chairs, depends on the type of plastic. For PE, it can become pipes and plastic bags. For PVC, it is good to make things like window frames. Nowadays, the refabricating factories are already there. With the development of technology, they can be better in the future. So, after processing recycled material, we don’t need to worry too much about refabricating. However, it is important to develop the design of new products to make the collection and recycle process easier. Design of products can help the sustainable plastic loop in many different ways.
Firstly, the products should be made by single type of plastic and be well signed, which can help people to divide different plastics and put them into right place of refabricating. If the product is made of different material, it should be able to disassemble.
Secondly, all plastic should be healthy, so that it can be used to make all type of products regardless of the usage. Thirdly, the design is not only about material. In the design process, designers can guide users to develop sustainable life. For example, they can design the products to be good in quality and easily repaired, so that people can use it for a longer time.
Regarding the processes involved in plastic recycle and the circularity economic studied in this course these are the challenges to overcome:
- Take out all the contamination due to: additives, non-polymer impurities and degradation.
- Monitor of plastics contamination across the different stages and by the contribution from the players across the plastics value chain
- Make all the appropriate considerations when designing their products and packaging with a view to later recovery.
- Establish partnerships to increase recycling education, and access to more recycling bins in public areas
- Implement technical assistance to communities to increase recycling and standardized education
In conclusion, our approach for the subject “Engineering for sustainable development” will be focus on the design part, the smaller loops in the circularity economy, the different ways of collecting plastic and making people and young generations aware of the importance of recycling this resource.