Major Aquafin project: 5 HUBER Belt Dryers BT for the thermal treatment of more than 120,000 tonnes of sewage sludge per year
HUBER SE will supply a total of five HUBER Belt Dryer BT units to the Belgian company Aquafin for the two sites in Roeselare and Beringen. The plants for drying and thermal utilisation of sewage sludge will treat a minimum capacity of 32,500 tonnes of dry substance or 120,446 tonnes of original substance with a dry residue (DR) content of 27% per year.
In addition to the HUBER belt dryers, the scope of supply includes the entire wet sludge logistics, cooling water supply, exhaust air treatment for the dryer and bunker exhaust air as well as the treatment and storage of the dry sludge. The total order for HUBER SE for approx. 40 million euros was placed in mid-2023.
Project constellation
The project is carried out by a team of three companies:
- Contractor: Stadsbader Group
- Technology partner for sludge drying: HUBER SE
- Engineering and study: Sweco
For the end customer Aquafin, this combines the strengths of a healthy construction company, a specialised technology partner in drying technology and an experienced engineering company with specific experience in the fields of hydraulic engineering, civil engineering, hydrology and (geo)stability.
The collaboration between the Stadsbader Group, HUBER and Sweco guarantees high-quality project execution thanks to local roots on the one hand and process and technical expertise on the other.
After submitting the approval documents at the end of 2023, the environmental permit for the Beringen site was granted after just over six months. The permit for the plant in Roeselare is also expected this year. This means that the engineering phase for this major project is as good as complete and the first work can start on site this year.
20 years, 82 plants and 1.8 million tonnes of sludge per year
In the last 20 years, HUBER Belt Dryers have processed 1.8 million tonnes of sludge per year in 82 plants worldwide. With the appointment of HUBER as technology partner, the project partners can draw on decades of practical experience in the supply, installation and commissioning of sludge drying plants. HUBER has already gained regional experience with its drying technology in the Benelux region: one of the largest belt drying plants, probably the largest in the world, is currently being built at the customer HVC in Alkmaar.
Aquafin – current sludge chain
Aquafin is a Belgian company that was founded in 1990 by the Flemish government and is responsible for the inter-municipal infrastructure and treatment of domestic wastewater. Every year, it produces around 350,000 tonnes of dewatered sludge with an average dry residue of 27%. The disposal of this sludge is currently organised via three disposal routes: One third of the sludge is dried using residual heat and fossil fuels and then utilised externally in the cement industry (co-incineration). One third is dewatered and processed under autothermal conditions in the sewage sludge recycling plant in Bruges. The remaining third is also dewatered and thermally recycled together with industrial waste by an external company.
Aquafin – new sludge chain
From 2026, Aquafin will initially dry up to a third of the dewatered sludge using HUBER Belt Dryer technology as part of its climate and energy targets. This will be done using residual heat that would otherwise be lost.
For this purpose, two largely analogue drying plants will be built in Roeselare and Beringen. The sewage sludge delivered by lorry from around 40 different sewage treatment plants is fed directly into the HUBER Belt Dryers by a crane system from the bunker via a downstream moving floor and thick sludge pumps.
In the Beringen plant, a total of 84,446 tonnes of dewatered sewage sludge per year are dried from 27 % to 90 % DR at an inlet temperature of 110 °C. Three HUBER Belt Dryers BT 28 are used for this purpose. In the Roeselare plant, two HUBER Belt Dryers BT 22 are used to dry 36,000 t/a of dewatered sewage sludge from 27 % to 90 % DR at an inlet temperature of 90 °C.
The bunker and dryer exhaust air are treated separately, with the dryer exhaust air undergoing a 4-stage cleaning process – with scrubbers, biofilters and downstream activated carbon filters. After drying, the sewage sludge is fed into a pellet press by screw conveyors and a bucket conveyor. The cooled pellets are then stored in dry material silos before being transported to Ghent.
Construction of a mono-incineration plant in Ghent
Aquafin will build a mono-incineration plant on the site of the steel company ArcelorMittal in the port of Ghent by 2026, in which the sewage sludge dried in Beringen and Roeselare will be utilised. ArcelorMittal will purchase 100% of the steam generated by the sludge treatment plant.
For the steel company, this is an additional source of energy for its internal steam network, further reducing the use of fossil fuels. The direct purchasing of the entire steam production in combination with the focus on raw material recovery (phosphorus) gives the overall project considerable ecological added value. This new plant will be designed, built, financed and maintained until 2046 by the BESIX Indaver consortium.
A prime example of sustainable resource management
With its belt drying technology, HUBER is making a significant contribution to Aquafin's goal of no longer using fossil fuels by 2030 and becoming a climate-neutral company in the long term. In addition, waste heat is utilised directly at the point of origin and the dried sewage sludge is transported to the utilisation site as an energy source. The large-scale Aquafin project is therefore a transferable example of sustainable resource management.
