October 23, 2023 –Paper is often seen as a green alternative to plastic, but the industry that produces it uses enormous quantities of water.
Companies in the pulp and paper sector say they are adopting new technologies to reduce the amount of water they need, but as our climate changes, are they moving fast enough?
One of the world’s largest pulp mills recently began operations in Uruguay, the UPM Paso de Los Toros facility in the centre of the country.
This came just as the nation was suffering its worst ever drought, sparking debate about its water use.
Uruguay’s capital, Montevideo, even ran out of fresh drinking water this year, after record low levels of rainfall.
For several months, the authorities had to take supplies from a river estuary where sea water mixes with fresh water, making tap water slightly salty.
Protestors, banging empty plastic bottles, came out on the streets, complaining that wood-pulping mills, and the forestry sector that supplies them, were using huge quantities of water.
“It’s true that there’s been a drought, but this crisis is caused by our economic model,” said Isabel Figari, one of the protestors. “Today, pulp mills have water, and we the people don’t.”
Uruguay’s pulp mills turn eucalyptus and pine wood into cellulose, which is then exported to be made into paper abroad.
The new facility in Paso de los Toros is run by Finnish company UPM. When working at full capacity it will produce 2.1 million tonnes of cellulose per year, doubling Uruguay’s total output.
This should see the country move from the world’s 12th to 11th largest producer, overtaking Chile.
The US is by far the biggest producer, followed by Brazil.
In UPM’s new mill the wood is chipped, then boiled with sodium hydroxide and sodium sulphide at high pressure. This dissolves the lignin in the wood leaving cellulose fibres.
The cellulose is then bleached using chlorine dioxide and hydrogen peroxide. The process needs a lot of water.
The mill takes 129 million litres of water a day from the local river, the Rio Negro. The waste water is then treated and pumped back into the river.
UPM runs another pulp mill, Fray Bentos, in south-west Uruguay. The company points out that both its facilities are several hundred kilometres from Montevideo, in areas where there is no water scarcity, so cannot be responsible for water shortages in the capital.
To reduce the amount of water it uses, the firm says it is applying the latest recycling technology. For example, when the wood chips are boiled in the Paso de Los Toros mill, the water vapour is condensed and used again.
After the cellulose is pulped, the water is extracted and then used in the subsequent bleaching process. Overall, the water is recycled 100 times before it is treated and is discharged into river.
“This is an area of continuous work and development,” says Marcos Battegazzore, vice president of UPM’s operations in Uruguay. “We have reduced the amount of water we take from the Uruguay River at Fray Bentos by almost 25%, and have also incorporated these water-saving technologies into our new plant in Paso de Los Toros.
“As technology develops there will be more possibilities to improve recycling levels within mills.”