Smurfit Kappa Nanterre mill's efforts to purify water have earned it satisfied customers and a decrease in complaints
July 2007
By Martin Koepenick
With a view of Chatou Island, where Renoir and Manet painted some of Impressionism's most revered masterpieces, Smurfit Kappa Nanterre makes fluting (105-140 g/m2 at 800 mm) from 100% recycled old corrugated containers (OCC). Located not far from the center of Paris, a challenge for any manufacturing site, it has become the first in France to try a new water purification system, manufacturing chlorine dioxide (ClO2) on-site, reducing the need for biocides, running cleaner and with fewer breaks.
Touring the massive industrial site of more than 16 ha with over 100 years of history, mill director Marc Olivier Girard speaks with conviction about the firm's commitment to being profitable for shareholders, and contributing positively to the local community and environment.
"The river Seine continues to become cleaner, based upon efforts by the authorities in Paris, local communities and private companies. There's a swimming pool near the Eiffel Tower, using water from the river, and in our case, we purify to make better paper more efficiently," says Girard.
Process engineer Valerie Raimbeault, who's been in charge of finding alternatives to traditional biocides, says that the settling unit, which used to be green with algae, is now totally clear.
The way the compact ClO2 unit works is to manufacture on-site by combining sodium chlorate and sulfuric acid. The unit runs automatically, meeting targets set by the mill.
There are two feed points at this time. "We want to reduce breaks and run clean. So, we measure on-line, adjusting the chlorine dioxide dosage in the water accordingly," explains Raimbeault. "We maintain a target level, making the biggest adjustments from summer to winter," she adds.
"We run more efficiently with regard to the pH, because ClO2 has the same efficiency for all pH, which is not the case for pH sensitive hypochlorite," says Girard. "Life is now easier for us in terms of routine operation and running cleaner."
Cleaning away the algae
According to Girard, the mill's primary problem with water from the Seine is suspended solids. He points out that there is much less plastic and debris in the Seine than many rivers, and the toughest days are after thunderstorms. "We have decreased water consumption tenfold over the past 20 years, so that helps in terms of energy savings and processing, as well," notes the mill director.
River water is first fed into a static settler, basically a big pond. After that the water is channeled into a sand filter. "Sometimes we have to clean the sand. The system works like a filter for a swimming pool, counter washing the sand," explains Raimbeault.
Some water is diverted to cool motors and other parts of the process. There is no mechanical treatment, but some biocide treatment. The chlorine dioxide dosages are applied just after filtration (before the settler) and just after the sand filtration.
By improving the quality of incoming water and reducing the addition of biocides, Smurfit Kappa Nanterre can now focus on addressing suspended solids in its process water, originating primarily from calcium carbonate, which is released from the OCC during pulping and processing.
Chlorine dioxide is a selective oxidizing biocide that affects essential cell mechanisms that are fundamental for life for bacteria and algae. Because of this microorganisms cannot become resistant.
ClO2 also oxidizes metals such as iron and manganese from the river, sulfides, humic acids and phenolic compounds. Because ClO2 is more selective than most oxidants in attacking organic compounds, AOx and trihalomethanes are not formed. Substitution reactions do not occur.
Looking ahead
While ClO2 is employed for feed water and cooling water, Girard would like to consider broader application of the technology. "Process water, wastewater, whitewater and cooling towers could all improve with this technology. In our case broadening the scope is largely one of mill logistics and cost efficiencies."
According to process engineer, Eka Chemicals, Bruno Bolduc, the firm's Purate generator is designed to handle incoming water, cooling water, and whitewater, depending on mill needs and issues. Some mills have already eliminated or minimized traditional biocides for all of these applications. "We will try to help Nanterre gain even more than it does now from the generator, including process water treatment, if it makes good economic sense," he says.
"Even though we sell all of our products within the Smurfit Group, these internal customers are very demanding," points out Girard. "Various measures to produce consistent quality, including our efforts to purify water, have earned us satisfied customers, and a decrease in complaints," he says proudly.
"The combination of efforts, ranging from all recycled furnish, including 40% household waste, much lower application of biocides, barging instead of trucking only, contributing to the local park, are all examples of our commitment to the local community and the Paris region," notes Girard.
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The small-scale reactor unit uses chlorate-based chemistry. Sodium chlorate is reduced with hydrogen peroxide by sulfuric acid to produce chlorine dioxide. The fast reaction speeds of this chemistry are one advantage. In addition, the absence of harmful by-products, such as chlorine and chloride are notable. The small-scale generator enables a ClO2 supply ranging from 0.5 kg/hour up to 100 kg/hour.
The equipment is housed in a cabinet that measures 200 cm high x 160 cm wide x 60 cm deep.
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