Holmen Paper’s paper mill produces 750,000 tonnes of paper a year. It takes 15 m³ of water to produce a single tonne of paper, which means that 11,250,000 m³ of water needs to be processed each year.
On top of this, the mill also produces drinking water for its entire workforce and purifies its own waste water. Another challenge facing the company was the need for efficient processes and use of space.
The raw water coming into the mill contains both eels and fish. Our Meva Rotoscreen screen with a slot width of five millimetres was the solution of choice for removing these from the water.
Meva Rotoscreen screens are also used to separate fibre from waste water after the paper-making process.
The mill’s own waste water treatment plant also features a Meva filter. The water that has been passed through this filter contains low levels of phosphorus, nitrogen and COD.
In addition, 400 m³ of raw water is filtered through twelve DynaSand filters every hour to prepare it for use in the paper production process, with polyaluminium chloride used as a flocculant. Ten percent of the treated water is used as drinking water. This is filtered twice – first through DynaSand filters and then through two DynaSand Carbon filters.
The table below shows the values for inflowing raw water sourced from the Motala Ström river system in Norrköping. The chart also includes data for the process water and for the drinking water in the paper mill.
Inflowing raw water
Turbidity: 4.8 FNU
Colour: 30 mg/I Pt
Process water after DynaSand filtration
Turbidity: 0.4 NTU
Drinking water after DynaSand Carbon filtration
Turbidity: 0.1 FNU
Colour: < 5 mg/I Pt
Aluminium: 0.04 mg/l
CODMn: 2.5 mg/l
Iron (Fe): < 0.05 mg/l
Manganese (Mn): < 0.05 mg/l