Recycling products Recycling products Biogas: approx. 4 million m³ per year via 3 km pipeline to the paper mill, where it is used to replace natural gas. Dry sulphur: approx. 25 tonnes per year. Sulphur is used as an anti-fungal crop protection agent in grape growing. Calcium: approx. 1000 tonnes per year. The calcium released during the water softening process is sold as chalk fertiliser for agriculture, following dewatering. Following filtration and disinfection, the return water is returned back to the paper mill, for reuse. IWE uses a small proportion of this water itself, to replace groundwater. With the installation of the sludge drying machine, we hope not only to satisfy all the environmental requirements but also to convert sludge into a valuable raw material for the cement industry. Bacterial granules: approx. 250 tonnes per year of excess slow-growing bacteria are delivered each year to purification plants that have lost their bacteria as a result of disruptions to the purification process or to start up new plants.