Design Engineering Recycling Technology

Designing for recycling in manufacturing industries

The future environmental impact of materials used in manufacturing can be determined at the design stage of a product. Currently, around 80% of electronics are being sent to landfills1 and according to the United Nations, 20-50 million metric tons of e-waste are discarded every year2. Ideally, manufacturers should strive for producing products that require less ‘end-of-pipe’ treatment whilst keeping in mind that the products still achieve their purpose, are feasible to manufacture, are safe and reliable and lastly they are competitively priced. Archiving all these goals can be steep, which is why some manufacturers do not prioritise designing for recycling. Designing for recycling can be costly and time consuming as it often requires capital for research and development and there are several can be risks due to the number of unknowns1.

Entire processes can be redesigned for example rethinking entry materials, additional or alternative products of the process or alternative technologies for specific processes. An example of this is in the paper manufacturing industry, recycled paper can be used to substitute for virgin tree pulp but it has shorter fibres which produces weaker paper which is not good to look at. The recycled pulp and the virgin pulp can be combined to produce recycled paper products that meet the strength and aesthetic requirements. This concept is known as source reduction as it makes use of less virgin materials3.

Packaging is a major aspect of designing for recycling. Plastics form the bulk of most packaging materials and are a growing part of the waste stream. When designing the types of plastics used for packaging, the properties should also be considered in terms of recyclability and biodegradability. Thermoplastics are easier to recycle than thermosets and elastomers. Thermoplastics become soft when heated and they can be moulded or shaped with pressure when cooled which also allows for reversible transformation. On the other hand, thermosets can be softened and moulded and set once hardened. Elastomers are rubber-like plastics which are not recyclable4. There have been some chemical engineering innovations that separate and reprocess plastics by machine without significant material breakdown which enables reuse of several plastic products3.

Another approach to designing for recycling is through systems thinking. This means rethinking the re-use of materials by other industries. It also includes use of methods such as life cycle assessments (LCA) which assess the environmental impact of a product from raw material extraction to material processing. Efficient distribution systems for products can also be used and codes can be identification of materials that are difficult to recognise5.

A lot of work still needs to be done especially for the treatment of class III renewable materials which are not technically and economically feasible to recycle such as fertilisers, detergents and lubricants. The main challenge arising from most of these materials is in the separation into recyclable components as things tend to naturally mix than to unmix (second law of thermodynamics) 4. There is potential for manufacturers to explore upfront additional chemical and physical separation techniques during the design phase which can be used in the later stages of a product’s lifecycle. This might result in simplification of designs such as using less raw materials which can be separated with more ease into reusable components.

Cited Works

  1. Design for recycling Residus 
  2. Earth 911
  3. Chemical Engineering Paper Recycling Recycle and Reuse
  4. Design for recycling Dartmouth
  5. Design for the environment

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