• Tamsin Lacourte

Kerbside sorted recycling vs Co-mingled recycling: Which is best?

In the UK, a staggering 500,000 tonnes of recycling was sent to landfill in 2018 because of contamination. According to Recycle Now, contamination can lead to entire lorries full of recycling being redirected to landfill or incinerators. That’s half a million of carefully sorted waste that is dumped because the wrong item was put in or because containers were not rinsed properly. An entirely avoidable situation…

In 2018, half a million of recycling was wasted because of contamination

While incorrect knowledge of what is accepted for recycling is a big challenge in improving recycling rates, there are a number of systemic issues that complicates recycling. One of them is the two different recycling collection systems: kerbside sorted recycling and co-mingled recycling. Kerbside sorting consists of separating materials into different bins and are emptied in different containers in the collection lorry. Co-mingled recycling, on the other hand, requires that all dry recycling are placed in a single bin and collected together in the lorry, before being sorted at a recycling facility.

According to a Huffington Post analysis, councils that conducted co-mingled recycling schemes reported higher levels of contamination than councils that offered kerbside sorting. For example, the London Borough of Newham reported contamination rates as high as 18.5%. In this council, glass is not accepted in dry recycling and, as a result, is a common contaminant of recycling loads. Paper recycling specialists DS Smith found that co-mingled recycling doubles the rate of contamination.

The success of kerbside sorting lies on the ability for waste collection crews to verify the quality of the recycling. When everything is placed together, it is difficult to detect whether there is a contaminant unless the bin is overflowing with wrongfully disposed items. Additionally, mixing materials can wet any paper and cardboard in the bin. Wet paper and card decompose more rapidly and causes fibres to shorten, making it harder to recycle. When moisture contents of paper and card are too high, they are not accepted for recycling and are sent to landfills or incinerators.

In comparison, a plastic bag in a glass bin is obvious. Some councils use kerbside sorting to their advantage by imposing stringent verification processes. Bath and North East Somerset Council, with contamination rates of approximately 1%, boast about their contamination policy that requires crew to leave behind non-recyclable items with a note explaining why. Strategies like this require time and effort but correlate with lower contamination rates since residents have a chance to learn from their mistakes and perform better the next time.

So why do councils continue to offer co-mingled recycling? It all boils down to space and costs. Not all households and flat complexes can accommodate multiple bins. Additionally, separate recycling streams require more lorries and crew. However, some argue that sending recycling to sorting facilities costs even more. These facilities charge on average £35 per tonne of recycling. The jury is still out but one thing is for certain, the recycling industry needs to be optimised, and fast, if we are to meet the UK's ambitious target of achieving recycling rates of 65% by 2035.