Water matters. Every year millions of cubic meters of water pass through SCA’s paper mills around the world. Paper production requires a lot of water and SCA has established ambitious water targets to use it as intelligently and sustainably as possible – especially in water-stressed countries like Mexico, where water really matters.
By using globally acknowledged methods from the World Resources Institute in combination with internal assessments, SCA has identified nine sites in six geographic areas of water shortage. The Sahagún tissue paper mill in Mexico is located in one such water-stressed area.
“Our mill in Sahagún is situated next to Mexico City’s metropolitan area, where water is scarce and therefore expensive,” says Roberto Deleón, plant manager at Sahagún.
Sahagún, inaugurated in the beginning of 2011, is the newest of all SCA plants worldwide. It was a turnkey project and came with a standard water-handling system, and several measures have been taken to reduce the amount of freshwater it uses.
“Once we had stabilized production, the idea was to optimize efficiency and the use of water,” Deleón says. “Initially we used 25 cubic meters of water per ton of produced tissue.”
Water plays an important role in nearly every step of the paper manufacturing process. SCA uses about 210 million cubic meters of water annually at its plants around the world. Water is used to transport fiber during the paper production process and as cooling water, with the breakdown between the two being 60–40. The cooling water has little or no impact on SCA’s water footprint. It’s the process water, the main part of the other 60 percent, that has been the focal point for the environmental department at SCA for many years. This water is being treated before emitted.
New techniques
“Our main target is to reduce both the amount of water we use by employing new and more environmentally sound techniques, and to make sure the effluent is cleaned and treated in a sustainable way,” says Patrik Isaksson, vice president for environmental affairs at SCA.
If environmental concerns weren’t enough, the cost of water would be sufficient incentive to reduce the amount of water used. For each reduction of one cubic meter of water per ton of paper produced, the annual savings amount to nearly 60,000 dollars.
“We were using a considerable amount of water in the deinking plant, where the recycled paper we use is made into pulp,” Deleón says. “By closing one design loop we could reuse water from the second stage of the papermaking process for pulp making.”
Through this action, and by closing the loop in the vacuum systems in the plant, Deleón and his colleagues managed to reduce water consumption from 25 to 18 cubic meters per ton of paper produced. A third action – closing the loop on the sealing system for all pumps in pulp production as well as in the paper machine – further reduced consumption to 15.7 cubic meters per ton.
“Our final target is 10 cubic meters per ton in 2016,” Deleón says. “To reach that we have to start dealing with circulation rates and ionic charges, which technically is more challenging, but we will get there one step at a time.”
Reduced water consumption
By the end of 2012, Sahagún had reduced its water consumtion by 15 percent. The plant has its own water treatment plant, using a biological system to reduce the organic content in the effluent water. This means that the Sahagún plant already meets the challenging new water targets set up by SCA, which say that all pulp and paper mills should be provided with mechanical and biological treatment of wastewater by 2015. Of the Group’s 40 pulp and paper mills, 38 have installed and 1 is in the process of installing biological effluent treatment plants.
(SCA Sahagún Tissue)