14 March 2025
Agrivert takes pride in reviewing its projects with customers to ensure they achieve their intended goals. With this in mind, we revisited the refurbishment and expansion of the Derby AD plant one year after its completion to assess the impact of the upgrades.
The project aimed to upgrade the front-end system by incorporating a reception and pre-treatment system similar to Agrivert’s tried-and-tested design used in other STGP food waste AD plants. Additionally, the plant was expanded with two new digesters and a system allowing the co-feeding of silages.
The refurbishment was designed to convert the plant to a conventional configuration to align it with the rest of STGP’s food waste plants and significantly improve capacity, energy generation, and overall resilience and reliability.
Operational Performance: Increased Processing and Energy Output
A key objective of the refurbishment was to increase the plant’s food waste processing capacity. Since the optimisation, the facility has successfully met its throughput target of 50,000 tonnes annually. This enhancement has enabled the plant to handle larger volumes of food waste, improving its ability to meet customer needs and maximising its renewable energy potential.
Energy production has also seen a marked improvement. Before the project, fluctuations in feedstock impacted gas output. With the newly optimised processes and additional digesters, the plant now generates 6 MWh of green gas annually—enough to heat approximately 6,000 homes each year.’
Andrew Simm, STGP Operations Director, confirmed these successes:
"The project has been tremendously successful. The ergonomic design has enabled more efficient use of staff on-site and created a better working environment. Within months of completing the project, the plant was consistently producing close to our maximum capacity for gas export to the grid. The two new tanks and silage feed system have allowed for more consistent gas production, enabling us to balance peaks and troughs in the food waste supply and maximise gas output. We are delighted to report that we have had very few snagging issues, and we regard the project as a huge success."
Technological Enhancements: Optimising Efficiency and Compliance
The refurbishment incorporated several technological advancements to improve processing efficiency:
- Front-End System Upgrade: The introduction of a bunker-fed automated hammermill feed system has significantly improved throughput and reliability, ensuring smoother processing of incoming waste.
- Pasteurisation Process: A new pasteurisation system has been installed to heat substrates to 72°C, ensuring full compliance with Animal By-Products regulations while improving biosecurity.
Additional Digesters: The addition of two cast in-situ digesters has optimised hydraulic retention time, stabilising gas output and ensuring a consistent energy yield throughout the year.
Community and Agricultural Benefits
The upgraded plant is not only a technical success but also a valuable asset to the Derby community. The refurbishment has supported local employment opportunities and strengthened ties with the area by providing an advanced food waste recycling facility.
Additionally, the plant produces around 60,000 cubic metres of nutrient-rich liquid bio-fertiliser annually, which is distributed to local farmlands, supporting sustainable agricultural practices and closing the nutrient loop.
A Year of Success and Future Collaboration
One year after the optimisation project, the Derby AD plant stands as a testament to the value of strategic investment in waste-to-energy technology. With improved processing capacity, enhanced operational reliability, and increased energy output, the plant is playing a vital role in the UK’s circular economy.
Agrivert is delighted with the positive feedback from STGP and looks forward to continuing its partnership to drive further innovation in anaerobic digestion and renewable energy.