Applying the circular economy to the water sector

With sustainability and resilience top priorities for the water industry, sustainability consultant Robert Spencer suggests ways the UK water sector can reduce waste, energy and materials use on projects and across schemes by adopting circular economy approaches.

Water companies and the Environment Agency are committed to embedding circular economy principles across their schemes and operations. While objectives vary across organisations, the overriding issue is demonstrating the benefit to customers and communities. A circular economy approach can achieve this by drawing together an organisation’s overall strategy with an adherence to wider goals, such as the sustainable development goals (SDG), whole-life asset management approaches, security of supply for key materials, natural capital accounting, partnership building and whole-life cost efficiencies. These different factors can then be communicated to consumers through innovative customer and stakeholder engagement approaches to clearly illustrate the trade-offs between different spending priorities.

The circular economy approach is designed to keep materials at their highest value for as long as possible by repurposing and recycling them once they have reached the end of their operational lives. By adopting this approach, organisations in the sector help create a more sustainable materials flow across schemes and the industry; reducing supply risks and price volatility for water and other infrastructure owners and operators; and achieving cost savings.

There are challenges to adopting a more circular way of doing things, such as the long lifecycle of infrastructure assets and figuring out how to move, store and repurpose huge amounts of materials across schemes. But there are also steps that water companies and flood-risk authorities can take to start embedding circular economy principles into schemes and operations to help move themselves and the industry forward, these include the following –

Work with nature

Many water companies are working with natural processes and investing in longer-term, holistic strategies to manage upland catchments in ways that slow the flow of water and improve its quality. This can reduce the need for development of new hard or grey infrastructure assets with all the costs in funds, materials and maintenance that entails.  Working with nature can lead to significant water treatment efficiencies, reduce downstream flooding to communities and enhance the natural environment. We worked with United Utilities in the Swindale Valley on river and floodplain restoration works to help store flood water upstream and improve water quality (see article ‘Three ways to encourage more natural flood management’). As the river now flows more slowly it collects less sediment. As a result, less sediment needs removing at the water company’s intake, requiring less intensive water treatment and therefore energy.

Incentivising land owners and managers to use smaller quantities of pesticides and fertilisers can also improve water quality, reducing the need to treat it as intensively, saving energy and costs. Working with the water company Affinity Water we developed and trialled a Payment for Ecosystem Services (PES) scheme, incentivising landowners and land managers along the Bow Brook, a sub-catchment of the River Loddon in Berkshire and Hampshire, to reduce the use of metaldehyde on their land, reducing treatment costs in the long term.

View waste as an opportunity

Sludge has long been a problem for water companies, but, when viewed differently, offers new and exciting examples of the circular economy at work. The availability of sludge can be a means of securing a degree of energy independence. Thermal hydrolysis technology, which works like a huge pressure cooker, can be used to increase the product of methane from sludge. This methane can be used as a renewable energy source to power the treatment plant, making it almost cost neutral. The process would also reduce solids for disposal, requiring less transportation off site, cutting carbon emissions. With Ofwat looking to kick-start a bioresources market that will incentivise water companies to look for the most efficient approach to wastewater sludge transport, treatment, recycling and disposal, there is an opportunity to develop even more low-carbon energy generation from sites, with a strategy that aims to reduce customer water bills.

AECOM, alongside Kier and Murphy, is helping upgrade Thames Water’s Deephams Sewage Treatment Works (STW) in north London to improve the water quality of the River Lee. This includes using innovative solutions such as integrated fixed-film activated sludge (IFAS) technology, installed into existing sludge tanks, to reduce costs and environmental impact. The IFAS media increases the surface area where bacteria can form, intensifying the treatment processes so that more sewage can be treated by fewer tanks. This has made the process more efficient, enabling the new treatment plant to be built in two thirds of the original footprint.

Create storage and recycling hubs

For infrastructure owners and operators, shared storage and renewal hubs and upcycling and re-manufacturing facilities are needed to address the timing and sequencing challenges that come with re-purposing surplus materials within and between schemes. Government bodies could set up hubs strategically alongside approval of large schemes. This will require local authority and Environment Agency (EA) cooperation and an intelligent, software-enabled marketplace to match material needs with surplus and end of life stock, and to ensure hubs run efficiently and effectively.

Make materials last longer

It’s possible to reduce and potentially eliminate waste by keeping materials and components in use and within the value chain for longer— central to a circular economy. Yorkshire Water is reusing waste filter media, from redundant sludge filter beds which would otherwise be regarded as waste, at its Esholt Wastewater Treatment Works (WwTW) in West Yorkshire by processing the material into construction grade aggregate for sale to developers and re-use within its own construction activities. Yorkshire Water reports that through this initiative, 37,000 tonnes of the aggregate were used in the construction of two new railway stations on the Leeds to Bradford line. A further 50,000 tonnes was sold to local and regional contractors working on construction projects in the locality.

Esholt also produces all of its own energy on site through renewables and low-carbon energy generation mostly through sewage reuse. Investing and scaling up similar pathfinder projects, and learning from the outcomes of such schemes, will help develop the innovations and methods needed to move the industry towards a circular economy.

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Developing a measure of success

The water industry needs a way to measure its success in shifting to circular economy models. This could be a measure of the ratio between a project’s raw materials consumption and financial value to track decoupling of resource consumption from scheme budgets. The real challenge is creating a system capable of painting a UK-wide picture of performance.  The Major Infrastructure – Resource Optimisation Group (or MI-ROG) is already helping here. Founded by AECOM, Highways England, National Grid, Network Rail and International Synergies, MI-ROG members now include 15 infrastructure operators, including the Environment Agency and Tideway, who share best practice and resource strategies for sustainable infrastructure delivery. Providing a collaborative space to come up with agreed circular economy measures across infrastructure operators is one of MI-ROG’s major achievements and guidance is set out in its second white paper

For more info, see the white paper – Measuring circular economy performance