Water plays a critical role in paper production, making responsible water use and treatment central to our sustainability commitments.

The Coronel Suárez mill in Argentina has operated an aerobic water treatment system since 2007. With recent investments in more efficient papermaking technologies and shifts in recycled fibre quality, the existing system was approaching its treatment capacity.

To strengthen performance and prepare for future demand, the mill completed a major upgrade in 2025 with the installation of an internal circulation anaerobic treatment system and new heat exchangers.

Integrated upstream of the existing aerobic basin, digester and settler, the anaerobic stage significantly reduces the organic load, lowering the Chemical Oxygen Demand (COD) entering the aerobic system by 75% compared with previous levels. This enhanced process stability allows the aerobic bacteria to operate more efficiently while also reducing surplus sludge generation.

The new heat exchangers further optimise performance by reducing water consumption and stabilising the temperature of the water before it enters the anaerobic reactor. This contributes to the proper functioning of the reactor and improves overall operational efficiency.

All system components were engineered to meet current operating conditions and accommodate future increases in production, including higher flow rates and greater organic loads.

As a result of these improvements, the Coronel Suárez mill achieved a 73% reduction in COD between 2024 and 2025, equivalent to approximately 106 tonnes of COD removed.

These upgrades mark a significant step forward in our long-term strategy to enhance water stewardship and reduce the environmental footprint of our operations.