Waste Management Case Study: Viridor, Rochester Plastic Recycling Facility

“Proof is in the pudding, and Expel worked. I am really impressed”.

Mark Gibson – Maintenance Supervisor – Viridor.

About the customer

Viridor is the largest UK-owned recycling, renewable energy and waste management company. 

Viridor announced that all its recyclable plastic waste would be reprocessed in the UK from 2020 as part of its recycling investment programme. Viridor’s full range of services includes recycling and waste advice and auditing; advanced materials recycling; glass and plastics reprocessing; composting; mechanical and biological treatment; anaerobic digestion; waste to energy; transport; collection; landfill disposal; and habitat restoration and management.

Project Background

The Rochester Plastic Recycling Facilities site runs approximately 16 optical sorting machines. These machines are critical to the site as they are needed to separate the non-recyclable plastics or plastics that are not PET. Compressed air is vital to the functionality of optical sorters. The performance of these machines is compromised if liquid water, oil emulsion fluids or solid particulates enter the compressed air lines – a problem known all too well to Maintenance Supervisor Mark Gibson. Exposure to compressed air contaminants damages the valves on optical sorting machines. The only way to rectify the problem is to replace the valves creating an unnecessary cost and impediment to the site’s overall efficiency.  

Furthermore, Viridor as a company are keen to make their sites as sustainable as possible and always looking for ways to reduce environmental impact. After learning about the Expel compressed air filter, Maintenance Supervisor Mark Gibson quickly realised how Expel could boost the site’s productivity and reduce the environmental impact of compressed air usage.

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Why did Rochester PRF Site choose Expel?

The site had refrigerant dryers and conventional compressed air filters installed to solve the problem of moisture and solid particulates in compressed air lines. However, these solutions did not eliminate the issues, exemplified by the large number of valves damaged by liquid water and needing constant replacement.

After installing Expel, the maintenance team noticed its effectiveness quickly. The maintenance team found they no longer had to replace moisture-damaged valves. So why has Expel succeeded where other solutions have failed? – The answer is simple. Expel has a unique patent-protected design that allows it to continually remove 99.999% of all liquid water, oil emulsion fluids and solid particulates down to 1 micron from compressed air lines. In contrast, traditional compressed air filters contain disposable internal elements that become less and less effective. Unlike Expel, they can never guarantee that these harmful contaminants will not reach critical machinery like optical sorting machines.

Refrigerant dryers were also proving problematic for this site because when the compressed air leaves the dryer, it has to travel a long distance before it reaches the optical sorting machines. Exposure to temperature changes causes the compressed air to fall below the dryer dewpoint, causing moisture. Expel can still operate in low temperatures, making it a far more reliable solution for the site.

These outstanding results were not unnoticed by Mark Gibson’s team and have attracted attention from other sites. For example, Maintenance Supervisor Andrzej Slimak from the Crayford Material Recycling Facility site was so impressed with these results that he asked us to visit his sites urgently to eradicate the moisture problem from compressed air lines as soon as possible. This site has since ordered units, and we are excited to hear about the results in due course!

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"Two months since installing Expel and I’ve not had to change one solenoid valve"

Mark Gibson – Maintenance Supervisor – Viridor.


Reduced Downtime

Reduced Maintenance

Increased Sustainability

Reduced Costs


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