When Less is More

Sofidel Soffass celebrates its PPI Award for Water Efficiency, but the work goes on.
GRAEME RODDEN

Soffass Cartiera mill in Porcari, Italy.

One of the main guiding principles of Sofidel is: less is more.

Through the use of modern technology and proper control, the company has shown it can lessen its environmental footprint and reduce waste while producing a high quality product.

Its Soffass Cartiera mill in Porcari, Italy, can be considered a flagship of the company, producing 120,000 metric tons/yr of tissue on three machines. It is also integrated with a large converting facility on site.

In 2017, Soffass earned the PPI Award for Water Efficiency. In a EUR 2.5 million (US$2.9 million) project, water consumption was cut to 3.9. m3/tonne. It previously had a consumption of 6 m3/tonne.

Fresh water consumption and how to reduce it is one of the hot point issues the industry faces. As a group, the Sofidel mills have an average water consumption of 7.1 m3/tonne, still well below industry averages for tissue mills using a virgin pulp furnish.

In its submission for the award, Sofidel noted that the mill is located “in the heart of an important industrial district where there is a high concentration of paper production and processing facilities.” Therefore, water demand on the local acquifers and rivers (Pescia, Serchio, and Arno) is high. Often, deep wells need to support water supply shortages.

Sofidel recognized the risk from the time it acquired the mill in the early 1980s and has always made water management a priority, working to be as efficient as possible in its tissue making processes.

Water consumption has always been below limits set by local authorities, but the new water treatment system has pushed the envelope even further.
As noted, the mill has three tissue machines. There are three clarifiers, one for each machine. The primary treated effluent then flows into a settling basin. The settled liquid flows to a 500-m3 chest in which a pump was installed to feed the new system. This is the connection between the old and the new, noted Assistant Production Manager Michele Antonio Navazio.

The “new” is a compact, three-sequence process that starts with an aerobic process that “drastically” reduces the amount of organic pollutants. This occurs in a 600-m3 basin. There are two turbo blowers that feed air into the tank to promote the development of the biomass.
The cleaned water then flows to the heart of the system, the ultra filtration process, two 45-m3 chests, which contain two four boxes each, in which up to 48 ultra filtration membrane modules can be installed, designed for maximum efficiency.

The membranes have a very small pore diameter. The effluent passes through the membranes, which act as a filter. Solids with a diameter as low as 0.1 micrometer can be collected. The remaining pollutants are dissolved and flow into the third stage and final stage.

Here, the final effluent is cleaned of any saline content by a reverse osmosis system. This produces water that is very demineralized. “We can send it back to the process instead of using well water,” Navazio says. “The recovered water is like fresh water.”

Since the system started up in 2014, the mill has saved more than 250,000 m3/yr of fresh water.

Strict control of the process is needed. Besides the tanks and blowers and other brick and mortar pieces, a large number of sensors were installed to keep track of all aspects of the process. “When you close up systems, there is a build-up in the circuits,” Navazio explains. “We need to keep strict control of all process variables.”

TREAT THEM NICELY
Prime among these is the bacteria in the aerobic stage. “We must watch the level of the bacteria,” Navazio adds. “If there are too many, they start to eat each other; too few, they don’t work efficiently. Also, different families of bacteria could generate.”

To ensure all goes smoothly, one of the process engineers in the plant, Raissa Lena, is also a biologist. “We are very kind to our bacteria,” Navazio says with a smile.

But it is important not to underestimate the importance of the system’s sensors, which are very sensitive. “From a process point of view, we need to have an idea at all times how the process is running, because we need to be able to act as quickly as possible to any upset. We are almost closed loop as far as water is concerned,” Navazio adds.

Besides the bacteria, strict control of water pH must be maintained. For example, using TCF or ECF pulp in the furnish could affect water pH. Water temperature is a key parameter as well. Continual fine-tuning of the system has occurred since it went online.

Solar panels help produce some energy for the mill.

The idea for the system came from Sofidel personnel, although its technology supplier developed the process. “They come twice a year for maintenance of the membranes,” Navazio says. “Otherwise, our operators know how to troubleshoot. They also do the cleaning and we can optimize the system ourselves. Our automation technician, Manual Berrettoni, can improve the control logic thanks to feedback from the lead operators.”

Training was not especially difficult and start-up was not an issue. But, Navazio adds, ensuring the proper chemical dose and establishing the right cleaning schedule was “picky.” But, because the mill has such low water consumption, “we can rapidly see if something goes wrong,” Navazio says.
Besides the reduction in fresh water use, the mill also saved money as it must pay a flat fee for the water it uses and a tax on the volume of water it discharges into the sewer system. Besides production and quality, water use is also discussed at a daily meeting.

With water being reused as much as technically possible, has the mill looked at the sludge that is taken from the settling basin after the clarifiers? Currently it is landfilled. Navazio says the mill is thinking about it, but Sofidel needs to look at the investment involved to see if it is feasible.

SUSTAINABILITY AT THE CORE
Founded in 1966 by Emi Stefani (chairman of Sofidel Group) and Giuseppe Lazzareschi, Sofidel has always believed strongly in making sustainability a core value in its corporate philosophy. This belief in sustainability is tied to the economic and social aspects of its operations as well as natural resources.

As noted, the mill in Porcari was purchased in the early 1980s. The company’s first mill was located in nearby Villa Basilica. Today, the Sofidel Group has 19 companies under its wing, operating in 13 countries, and produces more than one million metric tons/year of tissue.

It is all set to officially open its greenfield mill in Circleville, Ohio, in late 2018 and will add to its US capacity with a new mill to be built in Oklahoma with start-up scheduled for 2020.

Porcari became a hotbed of tissue production (Sofidel is by no means the only producer in the area, although it operates four mills in the region.) thanks to some farsighted vision by a mayor of Porcari, Vincenzo Da Massa Carrara, in the 1960s. The region has also become home to many suppliers to the industry. With access to the highway system and ports relatively nearby, abundant water and a favorable business climate, Navazio says the development of the region for tissue production is a “great and efficient marriage of all components.”

Following the acquisition of the Soffass mill, new tissue machines were added: PM 1 in 1982 and PM 2 in 1987. Each can now produce about 26,000 metric tons/year.

Inside the paper machine control room.

In the early 1990s, Sofidel went big, purchasing a Valmet Periformer unit that produces about 66,000 metric tons/yr. The machine was the dream of founder Giuseppe Lazzareschi. Sadly, he passed just before startup in September 1994. His son, Luigi, is now CEO of Sofidel.

The Soffass mill uses a 100 percent virgin pulp furnish, all from certified sources. It uses both softwood and hardwood pulp with the mix depending on the product being made. Softwood pulp comes mostly from the Nordic region of Europe, while hardwood comes mostly from South America with a bit from Spain. South American pulp arrives in the nearby ports of Livorno or Genoa and is trucked to the mill. Most of the European pulp arrives by train. Sofidel’s procurement policies are quite strict when it comes to provenance.

The mill produces all tissue products: bathroom, facial, napkin, and towel. Basis weights range from 14.5 to 35 g/m2. About 98 percent of the tissue stays onsite to be converted. The rest is sold as parent reels. Both private label and brand products are produced.

Its biggest market is domestic, with the UK and Germany also being good customers. It has moved a little into the US recently, but when Circleville starts up, this will stop. Sofidel is also building a mill in Poland, and when it opens, plans are for it to feed some of the German market. The company’s philosophy is to sell its products within 400 km (250 miles) of its mills.

PM 1 is a swing machine producing all four tissue varieties. PM 2 is dedicated to bathroom tissue. Both are crescent formers. PM 1 has a 4-ply rewinder as does PM 3.

Originally designed for bathroom tissue, PM 3 is now devoted to kitchen towel. Most of Sofidel’s European brands, particularly its leading Regina label, are made on PM 3. Regina was also developed at the onsite lab.

The twin wire PM 3 can run one-ply tissue. There is no mix tank before the machine because of the two-layer headbox. Hardwood and softwood pulps are always separated until the headbox.

Other than the new treatment system, some recent work at the mill can be seen as part of the ongoing sustainability philosophy. These are energy related. On PM 2, a new system in the forming area extracts energy from the water jet in the headbox.

Inverters were installed on the biggest drives in all four pulpers in the mill. They meter energy in the pulper so none is wasted.

Finally, an automatic reel change system was put on PM 3 to increase efficiency. In an order of milliseconds, it cuts the edge, applies glue and then threads rapidly. It eliminates manual changes and Navazio says considerable production gains have been realized.

In the future, less will continue to be more. It has joined the WWF Climate Savers project and plans to:
• reduce its direct emissions of CO2 per tonne of paper by 23 percent compared with 2009 levels;
• limit by 13 percent indirect emissions of CO2 caused by third parties within the value chain compared with 2010 values;
• cover 8 percent of annual fuel consumption from renewable resources.