A mobile plant-based approach to wastewater treatment which can be targeted at specific sites as required is being trialled by Scottish Water for the first time - the mobile reed beds can be easily moved between sites as needed.

Transportable reed beds were put in place at the firm’s Moscow Wastewater Treatment Works in East Ayrshire at the end of 2025 as part of the pilot, which aims to provide an additional level of nature-based filtration and treatment at smaller, remote treatment works as and when required.

Now, data gathered over the course of the last eight months shows that the reed beds – which have been grown in 20-yard roll-on roll-off skips that can be easily transported – are helping produce a cleaner final effluent and meeting the targets set at the start of the trial, with the potential to be rolled out more widely.

Reed beds are an established, environmentally-friendly way of filtering out contaminants such as phosphorus, nitrates, and organic biodegradable substances from wastewater effluent that are already employed at a number of Scottish Water sites in traditionally planted reed beds.

Operations team leader for the treatment works, Connor McCafferty, said:

“This portable reed bed is the first of its kind in Scotland. The flow comes into the reed bed after it has been through primary and secondary treatment processes already and filters through the stones where the reeds will essentially eat up any organic and biological matter that is left in the effluent at this point.

“This allows us to add an extra layer of filtration and treatment to the wastewater effluent that we deal with from the surrounding area, with the added benefit that the reed beds can easily be moved from site to site and scaled up or down as needed.”

He added:

“We’re seeing all our sites struggling with low flows, especially with climate change and how dry our summers are becoming, so the effluent that is coming to the site can be very highly concentrated when there is less surface water entering the sewer system. Equally when we’ve got heavy rain flushes, we’ve got a lot of organic matter that has settled in the sewers over time being flushed into the site.

“These reed beds are helping us to deal with those variations in wastewater flows, by improving the quality of the final effluent at the end of the treatment process and ensuring we are maintaining compliance.”

Reed beds help to reduce levels of organic matter by physically filtering it out, while also creating an oxygen rich environment that supports aerobic bacteria which consume and break down organic pollutants.

Research and development project manager at Scottish Water Cormac Halley commented:

“This approach is not only cost-effective and low carbon but also represents a first for Scotland.

“The operational team needed a solution that could be quickly set up with low energy consumption and the mobile reed beds have provided that. This is a good example of how the research and innovation team can work with operational teams across the business to come up with effective, environmentally friendly solutions and it is great to see how well the reeds are growing and thriving.

“The advantage of this unit is that it can be easily scaled up or moved to another site as needed, providing more flexibility and a lower carbon approach compared to building more concrete based structures to house treatment processes.”