Sharply monitored and circular water as the ultimate goal.
The companies on the Chemelot site take in surface water and also discharge wastewater. Circle Waste Water Services treats wastewater from all plants at Chemelot, complying with strict Dutch and European legislation. For Chemelot, the requirements are set out in the December 2020 water permit issued by the Limburg Water Board and the July 2018 nature permit issued by the Province of Limburg. These permits take into account the ecology of the (Border) Maas and downstream drinking water extraction.
We consider water quality very important and therefore do our utmost to comply with permit standards and continuously reduce discharges. In doing so, we continuously monitor the quality of the treated water. We also take targeted reduction measures and investigate the possibilities of a circular water system, in which discharges are reduced to (almost) zero.
How does our water purification system work?
At Chemelot, Circle Wastewater Services collects wastewater from more than 60 plants, including rainwater and domestic water. Factories make efforts to prevent substances from entering wastewater. From the factories, wastewater goes through the sewer system at Chemelot to the treatment plant, the Integral Wastewater Treatment Plant (IAZI) in Stein.
Our purification system treats water in 5 steps:
- Collection – by gravity to one central plant,
- Pre-purification -sinkable and floating particles (such as sand and microplastics) are removed.
- Biological purification – bacteria break down contaminants.
- Sedimentation – sludge sinks to the bottom, the treated water is discharged.
- Monitoring – 24/7 quality control of treated water.
The IAZI provides a very large reduction in the amount of substances ultimately discharged. The capacity of the IAZI corresponds to the capacity of a wastewater treatment plant to treat wastewater from about 1 million inhabitants.
What’s left in the purified water?
The permit lists more than 600 substances that could and should be in wastewater. Strict standards have been set for these substances and other substances are not allowed in either. In practice, far fewer substances are discharged. The substances that are discharged are, for example, salts that are not removed in biological wastewater treatment. For these substances, the concentration remains below the permitted concentration.
What about microplastics, PFAS and “substances of very high concern”?
Microplastics
Chemelot has been monitoring microplastics in discharged wastewater since 2021. Initial measurements showed that this was about 3,000 kg/yr. In 2023, measures were taken that reduced the amount of discharged microplastics by 66%. Research by the Department of Public Works shows that approximately 200,000 kg of microplastics from across the border enter the Netherlands via the Meuse River. Chemelot’s wastewater adds about 0.5% to this and the aim is to reduce this further.
PFAS
PFAS or products containing PFAS are not produced at Chemelot. Extinguishing agents containing PFAS have been used in the past, but these have largely been replaced and we are working on phasing them out completely.
Other substances
Some substances have received extra attention in the media.
- Pyrazole: In 2015, there was a period when pyrazole was insufficiently degraded and was found in unexpectedly high concentrations in the Meuse. At that time, there was no separate standard for pyrazole. Since then, a strict standard has been included in the permit, measures have been taken to meet it, and we have installed (the only one in the world) an on-line analyzer to optimally monitor this substance.
- Melamine: In 2016, the presence of Melamine in the water received more attention due to concerns from the drinking water company. A strict standard is now included in the permit for Melamine as well, and measures have been taken to meet it and an on-line analyzer has been installed.
- AMPA: the drinking water companies were unable to sufficiently remove the amount of AMPA present in the Meuse in their treatment plants. Because of Chemelot’s large contribution to AMPA in the Meuse, measures were taken to stop using the substance leading to AMPA and replace it with other substances.
- Vanadium: the permit includes a standard reduction for vanadium. A new invention has recently come on the market that is environmentally superior (less energy consumption, waste and water consumption), than the technique developed in recent years for reduction of vanadium at the plant. This new invention is now being investigated further.
- Cyanide: under normal circumstances, cyanide degrades very well in the IAZI. During major maintenance of the IAZI (every 15 years), cyanide degradation has not been optimal on a few occasions, causing concentrations just above the permit standard.
Sustainable water use
Chemelot uses approximately 45 million m³ of surface water annually, not drinking water. Within the Circular Water for Chemelot program, we are investigating reuse of treated wastewater so that we need to take in less water.
Chemelot is striving to achieve circular water management with the goal of reusing 100% treated wastewater for process and cooling water, so that structural discharge to the Meuse River decreases to (almost) zero.
At the same time, we will continue to work on a phased reduction of specific substances in the coming years in line with permit conditions.