Water management

From reducing fresh water intake and optimizing internal water cycles to managing complex wastewater treatment, Valmet’s comprehensive water management concepts are designed to meet the diverse needs of paper and board producers across varying water consumption scenarios. 

Effective water management is crucial in papermaking, as detrimental substances in the water can significantly impact production. These substances can reduce the effectiveness of additives, affect optical and strength properties, and cause issues with sizing, odor, drainage, and drying. For example, high salt concentrations can corrode machine parts and diminish the effectiveness of additives, ultimately affecting the paper’s strength. With advanced technologies and deep expertise, our concepts enable you to achieve reliable water quality, minimize environmental impact, and enhance overall process efficiency. 

Examples of Valmet's water management concepts

Here, you can learn about three different water management concepts designed for large and fast board production processes. These concepts are based on the amount of fresh water the production line uses. To ensure the paper machine operates optimally, certain basic conditions must be met:

• Directing all fresh water to the paper machine
• Using the counter-current principle for all process water, ensuring water flows opposite to the product flow for maximum efficiency
• Moving all makeup water from clean to dirty, using cleaner water first
• Maintaining stable process conditions, avoiding variations in temperature or pH levels
• Discharging wastewater from the pulp mill, keeping it separate from paper machine processes
• Maintaining separate water loops for different departments to prevent cross-contamination and ensure efficient water use
• Efficiently washing pulp before it reaches the paper machine, using pulp presses

All our concepts include fresh water and effluent water treatment plants and sludge handling. The main difference between these concepts is the increase in hydraulic capacity of the wastewater treatment plant (WWTP) as fresh water consumption decreases. The less fresh water used in the mill, the more water must be recirculated back into production after various wastewater treatment stages at the WWTP to maintain water quality balance. 

Current standard level with low fresh water consumption (5 - 7 m³/t)

Nowadays, typical fresh water consumption of a paper machine with best available water technologies is around 5-7 m³ per produced paper tonne. Preconditions have been taken care of and the machine runs smoothly. There is still potential to reduce fresh water consumption further.

OCC liner fluting line with fresh water consumption of 5-7 m³/t (effluent water 3.5-5.5 m³/t)

Minor fresh water consumption (3 – 5 m³/t)

When using less fresh water, process water needs to be treated more effectively to remove contaminants before it can be reused or discharged. Otherwise, high concentrations of contaminants can negatively affect the cleanliness and operation of the paper machine. Therefore, we need technologies to keep the water clean and prevent operational risks.

Ultrafiltration and dissolved air flotation are the key technologies in paper machine's internal water treatment. Dissolved air flotation for press section waters removes fines and pitch improving runnability. Valmet Ultrafiltration W removes solids, colloids, microstickies and bacteria from the paper machine’s clear filtrate. Ultrafiltration permeate can be used in paper machine’s showers instead of fresh water. When fresh water consumption is below 5 m³ per tonne of produced paper, pulp presses must be used in stock preparation.

OCC liner fluting line with fresh water consumption of 3-5 m³/t (effluent water 2.0-3.5 m³/t)

Minimal fresh water consumption (<3 m³/t)

When water consumption is very low, risks increase and more water treatment is needed. For example, if water treatment is not properly managed, increased salt concentration (conductivity), especially chloride ions, can lead to retention issues and machine corrosion. Therefore, advanced treatment of biologically treated water is required when fresh water consumption is below 3 m³ per tonne of produced paper.

With the combination of dissolved air flotation, membrane technology, and activated carbon filtration in advanced treatment, we can polish biologically treated water to fresh water quality, thus eliminating corrosion problems.

OCC liner fluting line with fresh water consumption below 3 m³/t

Enhance the water efficiency of your board and paper making lines with Valmet’s services, even with minor investments. Our technological solutions in fiber process equipment and rolls offer effective options to reduce water consumption, boost production efficiency, and lower costs.

Benchmarking provides a comprehensive view of your water efficiency. We can help you developing your roadmap, knowing where you are, what you can improve and how much, and the actions needed to achieve these improvements.