Exploring the Circular Economy: Insights from Dr. Bob Stear of Severn Trent

Welcome to the latest edition of our blog series, where we delve into pioneering ideas and discussions in the water sector. Today, we bring you fascinating insights from a recent conversation between Piers Clark and Dr. Bob Stear, Chief Engineer at Severn Trent, a leading UK water company. This discussion was part of the Exec Exchange podcast, where leaders share stories to inspire, inform, and educate their peers globally. In this episode, the focus was on the circular economy—what works and what doesn’t.

Meet Dr. Bob Stear

Dr. Bob Stear’s journey in civil engineering started on the south coast before propelling him across diverse roles at Severn Trent. From sewage treatment process scientist to Chief Engineer, Bob’s career has been driven by a desire to solve complex problems in innovative ways. His commitment to innovation is evident in Severn Trent’s adoption of circular economy principles.

Understanding the Circular Economy in Water Treatment

For Severn Trent, the circular economy is about getting the maximum value out of wastewater—over 2.5 billion liters a day. It’s a strategic shift from linear processes to biorefineries, with a focus on low-carbon, low-tech, nature-based solutions. Bob and his team have sought ways to recycle every byproduct of the sewage stream, turning potential waste into valuable resources.

1. Heat Energy:

Although heat networks haven’t taken off in the UK, they hold vast potential. The sector has attempted to leverage heat, but challenges remain.

2. Nutrients:

Severn Trent has made strides in recovering nutrients like nitrogen and phosphorus from wastewater. Innovative processes now allow for the chemical removal of ammonia and phosphorus, which traditionally would have been lost, thus contributing to both a circular economy and reduced greenhouse gas emissions.

3. Phosphorus Recovery:

By removing large amounts of phosphorus that historically ended up in the sea, Severn Trent is taking significant steps toward environmental sustainability.

4. Grit and Screenings:

Severn Trent recycles approximately 6,500 tons of grit annually. While screenings still predominantly end up in landfills, new pyrolysis processes are being piloted to better handle this waste.

5. Cellulose Recovery:

An intriguing aspect of Severn Trent’s strategy is recovering cellulose from toilet paper. They hope to transform it into biofuel, yet face regulatory and technical challenges along the way.

The Role of Innovation

Innovation isn’t without its hurdles, especially in areas like end-of-waste status regulations. Yet, perseverance in exploring various solutions underscores Bob’s belief in driving progress through “falling forward.”

Net Zero Ambitions and the Future

Severn Trent has committed to achieving net zero by 2030. They plan to invest significantly in reducing nitrous oxide emissions, which account for their largest greenhouse gas emissions. Innovations like the catalytic ActiLayer converter show promise in addressing these emissions economically.

Conclusion

Dr. Bob Stear’s insightful commentary highlights the ambitious scope of Severn Trent’s endeavors within the circular economy. From transforming heat energy and nutrients to exploring cellulose extraction for biofuels, their approaches offer valuable lessons for the water industry worldwide.

In closing, Piers Clark reminds listeners of the challenges and opportunities within the circular economy. If you are passionate about this subject and wish to share your own experiences and insights, reach out to join the conversation.

Stay tuned for more discussions and updates that highlight the transformative potential of the water sector.