Our Role in the Circular Economy
Robert White
Wastewater and the circular economy have become interconnected in the UK as part of efforts to address environmental sustainability, resource efficiency, and climate change. The circular economy (Return/Recycle/Re-use), as opposed to the traditional linear economy (Take/Make/Dispose), aims to keep resources in use for as long as possible, extract maximum value from them, and recover and regenerate products and materials at the end of their life cycle.
Wastewater management is a key area where the circular economy is largely, being applied effectively.
In the UK, wastewater management involves treating sewage and industrial water to remove contaminants before the water is returned to the environment.
There are a high number of exceptions where the process is not working effectively as the Sewage Treatment Works (STWs) have had repetitive problems with ‘Storm Overflows.’ This is where there is too much rainfall for the STWs to cope.
The other main area of concern is that phosphorus and nitrogen are prevalent in wastewater due to their use in agriculture and manufacturing. Resources are now dwindling yet their availability is critical for agricultural use. As contaminants in our wastewater, they are a threat to our eco-systems when re-introduced to our waterways. The water companies are now facing stringent limits to ensure our waterways are not suffocated.
So how is wastewater being processed for secondary use in the UK?
Nutrient recovery
Wastewater contains valuable nutrients, especially phosphorus and nitrogen, which can be recovered and used as fertilisers in agriculture. UK water companies are now exploring technologies to extract these nutrients from sewage sludge. Phosphorus is critical for food production, but it’s a limited resource. Wastewater treatment plants are looking to capture phosphorus before it reaches water bodies, where it could cause pollution. This technology is now available.
Water re-use and recycling
Wastewater can be treated to a high standard and reused for non-potable purposes such as irrigation, industrial processes, or even flushing toilets. This reduces demand for freshwater resources.
Energy recovery
One of the most prominent applications of the circular economy in wastewater treatment is the generation of renewable energy through anaerobic digestion. This process breaks down organic matter in wastewater (such as sewage sludge) to produce biogas, which can be used to generate electricity or heat.
Several UK wastewater treatment plants have become energy-neutral or energy-positive, meaning they generate more energy than they consume, thanks to biogas production.
Biosolids and wastewater for agriculture
After treatment, sewage sludge can be processed into biosolids, which are rich in organic matter and nutrients. These biosolids can be applied to agricultural land to improve soil health and reduce the need for synthetic fertilizers. In the UK, this practice is heavily regulated to ensure environmental safety.
Circular manufacturing and industrial symbiosis
Industries are increasingly collaborating with water utilities to reuse treated wastewater in their manufacturing processes. This is part of broader industrial symbiosis, where waste from one process (in this case, treated wastewater) becomes a resource for another.
Sludge as a resource
Wastewater treatment results in sludge, which contains organic materials that can be repurposed. Besides biogas, treated sludge (biosolids) can be used in construction materials, soil conditioners, or even for land reclamation projects.
Where is PWS helping with the wastewater circular economy?
Separating phosphorus and nitrogen from treated water
Our BNR (Biological Nutrient Removal) plants and solutions are able to remove Phosphorus and Nitrogen from treated water before the water is returned to our waterways. Solutions which tackle this as follows:
- NUTREM® –unique, compact and efficient advanced Biological Nutrient Removal system
offering industry-leading results -
CONVOX® – innovative system for converting existing activated sewage sludge treatment works to Biological Nutrient Removal
Water re-use and recycling
An example of PWS involvement here, has been the use of our PureSBR technology to irrigate golf club greens from the wastewater generated from the club house. Course irrigation is one of the biggest expenditures faced by golf clubs.
Pure SBR has also been used at remote leisure locations and venues where the people traffic volume fluctuates by season and the grounds require irrigations such as Audley End House in Essex.
- PureSBR – efficient, reliable and robust continuous flow system, particularly useful on isolated sites. Reactors can be built in phases as volume grows, producing grey water for re-use or exit to waterways
Sustainable solutions for STW upgrades
- De Hoxar Spiral Separator – complete, compact gravity settlement device replacing any number of settlement tanks and separating sludge from water within a compact space
- Filtration+ – plug and play filtration unit, providing an effective additional treatment step for the reduction of suspended solids in final effluent
Our R&D continues to find viable solutions for the whole wastewater circular economy and latest research has investigated solutions for storm overflows and biogas opportunities.
Challenges and Opportunities
Regulatory Barriers
In the UK, stringent regulations exist around the reuse of wastewater and sludge, especially in agriculture.
Public Perception
Public acceptance of recycled water (for direct potable use) is a challenge. Currently, water reuse in the UK is mainly non-potable, but as water scarcity becomes a more pressing issue, it may be necessary to explore direct reuse.
Investment Needs
Implementing circular economy practices in wastewater management requires significant investment in infrastructure and technology. The UK government and regulatory bodies are increasingly supporting these investments through funding and innovation programs. The Labour Government’s new ‘Special Measures Bill for the Water Industry’ tackles targets and responsibilities of the water companies. Read more here.
Climate Change
As the UK faces more extreme weather patterns due to climate change (e.g., droughts and flooding), the circular economy provides a way to create more resilient water and wastewater systems. By recovering resources and reusing water, the sector can hopefully mitigate the impact of these changes.
Get in touch if you would like more information…
Article by Robert White, Plantwork Systems Managing Director