Closed Loop & Open Loop Systems

Many cases of recycling only help postpone permanent waste generation. This happens if an original material gradually loses its quality while being recycled and cannot return to the same manufacturing process. It has to be reprocessed to lower-grade products, which are not necessarily recyclable. 

This way of recycling, when a material lives a few lives but becomes less and less usable or pure or safe along its way to the landfill, is often termed “downcycling”. In terms of sustainability, it means being “less bad”, but still not good enough.

Click on the image to enlarge

Open Loop System

Open-loop recycling basically means that a material is not recycled indefinitely and is eventually excluded from the utilization loop and becomes waste. In the diagram opposite, natural resources are extracted from the environment and transformed into a product via the manufacturing process.

After its use, the product may be discarded as one of the outputs:

(a) Whole product that is not needed anymore;

(b) Whole product that became obsolete (although still functional);

(c) Non-functional or old product because of its limited lifetime;

(d) Recyclable / reusable parts or scrapped materials; and

(e) Non-recyclable refuse.

Those outputs enter one of the post-use channels – reuse, recycle, and garbage disposal, the latter contributing to the landfill. Reuse channel is usually limited, just postponing garbage disposal. Recycling loop results in producing another material, which is typically of lower grade and purity than the original material. It may be transformed further into a different product, which after use creates similar outputs. In the long run, a small part of the original resource may be stuck in the loop, but the majority of it becomes disposed of.

Click on the image to enlarge

Closed Loop System

Closed-loop recycling is a more sustainable concept, which means that recycling of a material can be done indefinitely without degradation of properties. In this case, conversion of the used product back to raw material allows for the repeated manufacturing of the same product over and over again.

A few things to consider:

  • The recycled materials should provide the same quality of the product (no deterioration). For example, almost all recycled aluminium from soda cans is suitable to produce the same cans.
  • There should be no accumulation of contaminants or toxins in the multiple recycling loops, which can make the secondary product less safe.
  • The recycled material can also feed manufacturing process for a different product or industry, which may require a different type of recycling.

(Source: Images and text source: Recycling: open-loop versus closed-loop thinking, Penn State University, Mark Fedkin)

Knowledge Centre

In this section there is a small number of documents and images. There are several videos in the Circular Economy YouTube Channel Closed Loop playlist.