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Fast and efficient sludge recovery

The Geotube® method has proved to be unbeatable for the processing of sludge from pulp mills, for example.

In the treatment of process sludge, the TenCate Geotube® method is positively ingenious: simple and effective. At a chemi-thermomechanical pulp (CTMP) mill in Rockhammar, Sweden, these large black tubes constructed of specially engineered textile were so effective in the treatment of the sludge accumulated at the bottom of the largest process water basin that there was talk of additional work with the client. Sito was the main contractor for the project.

“During the project, all the contaminant concentrations in the plant’s effluent remained within the permitted limits,” adds project manager Vesa Isokauppila with satisfaction.

BillerudKorsnäs AB is a leading manufacturer of renewable packaging materials. One of the company’s eight production plants is located in Rockhammar. The mill produces over 90,000 tonnes of CTMP pulps a year.

The production of pulp and paper unavoidably generates large amounts of sludge, which is passed on to the mills’ wastewater treatment systems.  “Over time, it tends to accumulate at the bottom of the process water basins. From there, is should naturally be processed and removed sooner rather than later. Geotube technology is an ideal method for this,” says Vesa Isokauppila.

The sludge is pumped into the geotube made of a special textile several times, and the filtered clean water can be led back into the process or the terrain. In the full geotube, the sludge continues to dry until it can be utilized in applications such as construction or as a fuel, depending on its properties.

“In Rockhammar, the primary plan is to use the dried sludge next summer to coat the industrial plant’s own landfill,” Vesa Isokauppila continues.

The processing of the large sludge basin at Rockhammar took about three months. The plant continued to operate during the project as normal.

Work will continue on the second, smaller basin.

Photo: Geotube® field –  the first layer near completion.

Text: Dakota Lavento