Recycling : A lasting partnership brings innovative waste sorting to Firminy
The Firminy sorting centre, first built in 2000 and fully modernised in 2023, is now operated by TrivalLoire — Suez's dedicated subsidiary — under a public service delegation for Saint-Étienne Métropole. Serving a catchment area of nearly 670,000 inhabitants, the plant processes around 45,000 tonnes of packaging waste each year at a throughput of 15 t/h, drawing on the advanced technologies of French intelligent sorting specialist Pellenc ST — a trusted partner at the site since 2002.
"At Firminy, we have been working with Pellenc ST since 2002," notes Yves Defour, Director of the sorting centre. When local authorities committed €33 million to modernise the facility in 2023, re-equipping it with Pellenc ST technology was, by his account, a natural choice.
A pioneering approach to material separation
The rebuilt site is designed to recover 13 material fractions — five fibrous materials, four plastic categories (clear PET, PE-PP, flexible plastics and rigid French Development Stream), food cartons, aluminium, small aluminium and steel. Working across two shifts, it relies on 13 Mistral+ CONNECT™ units.
Ahead of the optical sorting stages, two fully automated grapple cranes handle material in the reception hall, saving space, improving fuel efficiency and reducing accident risks. Conventional mechanical sorting then prepares the hollow-body and flat-body streams for further separation.
The real step change lies in the six machines dedicated to 3D sorting, where Firminy's key innovation — the CNS BRAIN™ artificial intelligence module — comes into play. Developed by Pellenc ST's R&D teams, this deep-learning neural network has been trained on millions of images to identify unique object characteristics such as shape, size and subtle visual differences. Combined with NIR/VIS sensors, it can handle highly complex sorting operations and, according to the manufacturer, deliver up to a 2% improvement in the purity of sorted materials.
Intelligent recovery, high returns
At Firminy, the three Mistral+ CONNECT™ units assigned to clear PET recovery carry the CNS BRAIN™ PET module, while the two units handling the PE-PP mix are fitted with a specialised version.
"The CNS BRAIN™ PET optimises the capture of clear PET bottles," confirms Defour.
"We trained the AI on thousands of bottle images, including dirty bottles or those with labels that obstruct material identification, ensuring they can still be accurately recognised," adds Romain Galia, Pellenc ST After-Sales Technician. The same principle applies to PE-PP recovery, where the neural network sharpens the separation of rigid and flexible products for measurable gains in output purity.
A notable feature is how lightly the upgrade sits on existing infrastructure. "Without the need for additional cameras, this option can be implemented simply through software updates, with no extra installation work or production line stoppages. Energy-efficient and straightforward to deploy across an existing machine fleet, these lightweight upgrades require no specialised maintenance," explains Galia.
The module supports a broad range of applications, from PE purification and fibrous material sorting to wood grading and PE/PP differentiation — and the commercial case is quick to make. "By improving capture rates and output stream purity, we can deliver ROI to operators within three to six months."
An enduring alliance
Elsewhere on the line, seven Mistral+ CONNECT™ units on the 2D sorting stage are equipped with TURBOSORTER™, which stabilises lightweight objects on the conveyor. Three of these also carry the TOP SPEED™ option, lifting sorting performance to 4.5 m/sec against the standard 3 m/sec.
"The combination of all these technologies improves yield, performance, and purity across every category of recoverable material," highlights Defour. That includes grade 2.05/2.06 white paper varieties, sorted separately at the request of local authorities.
More than two decades on, the collaboration shows no sign of slowing. By analysing data from the Mistral+ CONNECT™ units through the SMART&SHARE™ SaaS application, Suez and Pellenc ST continue to identify fresh optimisation opportunities — sustaining a shared commitment to innovation, efficiency and the advancement of the circular economy.
