Purely important water

Living next to a mill you would notice fast, if the mills emissions such as the sulphur emissions into air were not monitored.
"Equally important are waters surrounding the mills. All waters next to mills and their fish stock are monitored," says Metsä Fibre's Kemi mill's production manager Tomi Seppä. Seppä is not able to say which of the mill's environmental efficiency is more important: water or air. "Both are equally important."

The waters surrounding the mills are really kept clean. A concrete example of this is that the if you are using the sauna of the Äänekoski mill guest house and want to have a dip in the lake, it's the same lake to where the mill's process waters are released after cleaning.
"It is from the upstream of the same lake where the Finland capitol area will gets its drinking water. As you might guess, the purity of drinking water is analysed and monitored by third parties," says Metsä Board's director of sustainability and energy Soili Hietanen.

Water is a purely vital for pulp and paperboard manufacturing, because water is needed at every stage of production. Hietanen says that, for example, in the manufacturing of paperboard, process water keeps logs fresh, it helps to separate wood fibres for the paperboard production process, and it carries these fibres to different stages of the production process. "Water is also needed for cleaning, cooling, and in smaller quantities for steam generation production."

Not using but recycling process water

Since water is used as efficiently as possible, the mills could speak rather about recycling the water than using it: one litre of water goes around the mill up to 15 times.
"Water is recycled if the process allows it. The pulp mill's washing water is recycled upstream: from the brown mass container to a cleaner pulp container. Similarly, water is recycled in bleaching and drying," says Seppä.

Recycling water has had a major impact on Metsä Fibre's water balance sheet: between 2007 and 2015 the amount of wastewater has decreased by 40%. Also, Metsä Board has systematically reduced its water consumption, in 2010–2015 Metsä Board's water use has decreased by 16%.
"For example, in 2015, Metsä Board used 105 million cubic meters of water, of which 99% was surface water from rivers and lakes. Water is used effectively, the efficiency reduces the amount of waste water and energy savings, which in turn have a positive impact on the climate," Hietanen says.

Below the strict emission levels

At the mills, use of water is monitored on how much water comes to the wastewater treatment plant, and the follow-up is done on a daily basis: If a morning meeting noted that the wastewater levels are high, it is researched immediately. The next morning, it's analysed has the situation improved. The reasons for the high wastewater level can be from a number of things, explains Seppä.

The water is purified by biological treatment plants, which removes about 98% of the load of the water. After the water treatment plant, there are still some small amounts of residues, for example phosphorus (P), a combination of organic chlorine compounds (AOX) or microbial depleting substances (COD).

Exact boundaries are set to emissions in the mill's environmental permit, but they must also meet the EU-level BAT-values. At all Metsä Group's mills, the emissions are well below the BAT maximum levels.
This is worth remembering, because globally there are areas with no BAT values and no strict environmental figures – this is the case, for example, in North America.