Evaluation of the pH of solid residues generated in the cellulose industry adequate to the sludge hygienization for use in agriculture

This paper looks into the possibility of using solid residues generated in the cellulose production process to hygienize sewage sludge for fertilization. During the cellulose fabrication process, dregs, grits and vegetable biomass ashes are generated. Seven experiments were conducted in the Hydraulic Research Institute´s laboratory at UFRGS, in order to determine the pH values of the three residues in analysis-ashes, dregs, grits and the combinations of sludge/ash, sludge/grits and sludge/dregs- at the beginning (IT) and at the end (after two hours-FT). The preparation of the dregs, grits and ash solutions consisted of the weighing of 20 g of each residue and its dissolution in 80 ml of water, thus obtaining the solutions of grits, dregs and ashes. The pH values of the samples were analyzed using bench pH-meter. The ashes, grits, the mixture sludge/ash and sludge/grits displayed an accentuated basic character due to their pH values which were ≥12. The dregs and the mixture sludge/dregs presented a less accentuated basic character than the ashes and the grits, with a pH equal to 9. The results show that the ashes and the grits can be used in the hygienization of sewage sludge.