· mill. Bleached and unbleached pulp mills will have different amounts of biosludge, the amount is normally in the range of 5 – 10 kg DS/ADT. The Södra Cell Värö mill in Sweden initially installed a system with a capacity to treat ton DS of secondary sludge per day in 2002 (Figure 5). Figure 5. Södra Cell Värö hydrolysis plant (2002)