it is noted that if the procedure described hereinbelow is not performed addition of sulfuric acid h 2 so 4 for hydrolysis to the sludge result in immediate precipitation of gypsum caso 4 2h 2 o in the same fraction as the cellulose the gypsum rendered their selective isolation difficult cellulose fibers could not be isolated when an acid was used which produced water insoluble salts thus in order to achieve an effective separation of the cellulose fibers the process was carried out as follows 1 sludge cellulose source was collected and the total solids content was measured 2 based on the cellulose source used the material was optionally homogenized by ultrathorax homogenizer 3 an acid such as 0 5m hcl was gradually added until gas evolution ceased 4 the material was heated to 50 60 u00b0 c while stirring followed by centrifugation 5 the supernatant was removed and fresh acid was added to wash the solid fraction the cycle is repeated 3 times 6 following the 3 rd acid treatment the acid was removed by centrifugation and the material was washed 3 times in deionized water to obtain a suspension of cellulose fibers protocol for preparation of ncc cellulose whiskers from paper pulp waste 1 3 5 gr of cellulose obtained in accordance with.