Scotland on the Way to Net Zero: Water Treatment Technology Advancement to Boost the Progress

wastewater treatment in scotland net zero
The Nigg wastewater treatment plant (WWTP) services around a quarter of a million people from Aberdeen and the surrounding area. Source: Scottish Water

Scottish Water Services, a water treatment and distribution company, is finding itself ahead of its own plans. The company’s initial plan was to reach net zero carbon emissions by 2040. However, with the current pace of its technological development, it may happen even sooner. A wastewater treatment station in Nigg is the first to utilize biogas in energy production, which brings a drastic “carbon footprint” decrease.

Circular Economy in Water Treatment

The Nigg wastewater treatment plant (WWTP) services around a quarter of a million people from Aberdeen and the surrounding area. As of now, the Nigg plant produces 80 to 90 percent of the electricity it needs via two Combined Heat and Power engines. Due to this, the plant will no longer rely on external energy sources in the long run. There is a positive tendency already: the plant has halved its carbon emission since 2019.

Creating a circular economy within a site is the key to fast transition to net zero emission operation. By 2040 Scottish Water has committed to reaching this goal — 5 years ahead of the Scottish Government’s plan for carbon neutrality.

«When you consider the quantity of wastewater that we are treating on a daily basis, being able to turn that into something with a tangible use and creating a circular economy is a key strand of our route map towards net zero,» — Simon Wrigglesworth, director of Scottish Water Services Grampian.

Value to the Waste: Getting the Most of It

The new energy production technology now allows the Nigg WWTP to treat additional water sludge on site, increasing the biogas production by 25 to 30 per cent. Biogas is a mixture of gasses rich in methane, widely used as fuel. This is how the wastewater treatment plant generates its own electricity and moves away from external energy sources.

«We are determined to do all we can to make our sites as green as possible as we focus on reaching our target of net zero emissions by 2040, and recognising the value we can generate from waste is absolutely vital to that,» — Simon Wrigglesworth, director of Scottish Water Services Grampian.

On the Way to Net Zero

Last year the United Kingdom released the world’s first sector-wide plan to deliver net zero carbon emissions by 2030. Portugal, namely the Águas de Portugal water utility group joined the so-called “2030 club” and now aims to become carbon neutral within a decade.

Scotland is taking its own way to energy neutrality. To reach net zero emissions by 2040, Scottish Water has published a route map as part of a strategic plan entitled ‘A Sustainable Future Together’. The plan focuses on five key ideas, among which are becoming energy-efficient and investing in renewable power technologies. 

As of today, the Scottish Water run WWTP in Nigg treats about 983 megalitres of water daily, generating nitrous oxide (N₂O) and methane. By 2040 the company aims to optimize its water treatment facilities and dramatically reduce nitrous oxide production. By using the biogas produced as part of the treatment process as fuel for the new boiler, as well as recovering and reusing heat from the two CHP engines, Scottish Water said it had halved the amount of oil used in the boiler. The optimization will allow the company to cut the harmful emissions (about 1300 tons of carbon dioxide per year) but also lead to a cost saving of over £250,000 per annum.