Sewage Sludge Processing at Arcelor Mittal

The installation is intended to process the biomass that remains after the purification of domestic waste water. This biomass, created by the growth of the micro-organisms that do the purifying work, contains a wealth of energy and raw materials. Aquafin already produces fully green energy on this basis, in the form of biogas, and right now at one Antwerp location also biomethane, for injection into the natural gas network. The new installation, which should be operational in 2026, will be able to make even more use of the biomass delivered to it. As this is a mono-processor, the sludge will not be diluted with other substances, enabling maximum recovery of energy and raw materials.

Using a European tender procedure with competition-oriented dialogue, Aquafin went in search of a partner for the design, construction, financing and maintenance of the mono-processor. The DBFMO contract was recently awarded to the Besix-Indaver consortium, which is setting up a Special Purpose Vehicle (SPV) for this purpose.

Pierre Sironval, Deputy CEO of Besix Group: “Besix is particularly proud to have been selected for the design, construction, financing, operations and long-term maintenance of this state-of-the-art mono-combustion sludge treatment plant. The installation is exemplary in terms of circularity and net environmental impact. Besix has built up a global portfolio of different industrial projects of similar or greater size that take advantage of the diversity of expertise available in the Group: project financing, design, engineering, environmental considerations, construction, operations and maintenance. We look forward to developing the project together with our partner Indaver, a top player in many different types of waste processing installations. We will be joining forces to deliver a groundbreaking installation to our customer Aquafin, whom I would like to thank for their trust in awarding us this future-oriented project.”

“Indaver has long been a pacesetter in the transition to a circular economy”, says Indaver CEO Paul De Bruycker. “The circular economy will succeed only if everyone in the chain assumes their role and responsibilities. By closing high-quality material cycles, we can use raw materials again and again and contribute to the circular economy. Waste is no longer an unwanted end product, but a stream from which we create value. In close cooperation with our partner Besix and with all stakeholders, we will also be maximising the value of Aquafin’s water treatment sludge by recovering phosphorus in the longer term.”

On the Arcelor Mittal site

The location of the new installation has been determined for some time. ArcelorMittal is giving Aquafin a building right on the site and will purchase, 100% of the steam produced by the sludge processor. For the steel company, this is an additional energy source for their internal steam network, further reducing the use of fossil fuels. The direct uptake of the entire steam production combined with the focus on raw material recovery makes this installation an example for Europe.

“In determining the ideal location, the ecological arguments were decisive for us,” says Jan Goossens, CEO Aquafin. “We took as our starting point a model in which we could see, for each potential location, the CO₂-impact of all sludge transportation in Flanders. It is important that the sludge transporters drive as few kilometres as possible through Flanders to get their cargo to its final destination. Also essential were the possibilities to make optimal use of the energy produced at and around potential sites, with a view to an optimal solution for Flanders as a whole. The initiatives for carbon capture that are in the pipeline in the port of Ghent further strengthened ArcelorMittal’s position.”

“Arcelor Mittal Belgium has a passion for energy efficiency and circularity”, says Manfred Van Vlierberghe, CEO ArcelorMittal Belgium. “We continue to invest and launch new projects to fulfil our pioneering role in energy and climate transition. By using the high-pressure steam from Aquafin’s sludge processing process in our steel production process, we are making our energy consumption even greener. In this way we give an additional impetus towards the concrete implementation of our sustainability strategy for an increasingly energy-efficient company, while heading towards climate neutrality in 2050.”

Sustainable recovery of phosphorus

In a follow-up phase, Aquafin is planning to start up full-scale phosphorus recovery, representing some 2,000 tonnes of pure phosporus a year. By opting for mono-processing, phosphorus can be recovered more efficiently from biomass. Phosphorus is an essential building block for life, being among other things an important component of our DNA, our cell walls and our bones. We ingest it via our food, and it is also a basic component in mineral fertilisers for agriculture and horticulture. Phosphate ores are, however, a finite resource, and with only limited supplies naturally present in Europe. Via our food, phosphorus finds its way into domestic waste water, from where Aquafin will recover it with this new sludge processor.

The sludge mono-processor will carry out the end treatment of two-thirds of all Flemish sludge from domestic waste water. Aquafin is leading this extensive DBFMO project with tight reins to ensure that the far-reaching ecological objectives can be achieved.
The project is fully in line with Aquafin’s ambition to cease using fossil fuels by 2030 and to evolve towards climate-neutral business operations in the long term.