Enzymatic deinking for recycling of office waste paper

Office waste paper constitutes an excellent low cost and high quality fibre source for the papermaking industry. Limitations in the application of conventional deinking to such paper are related to negative environmental impacts chemicals can cause, hence enzymatic deinking is receiving growing attention. This study is focused on the investigation of the effect of cellulases application on the deinking of office waste paper. The methodology involved: preparation of samples, impregnation, repulping, enzymatic treatment, flotation, papermaking, and finally evaluation of optical properties. Five preparations, working under acidic and neutral conditions, were tested (Cellusoft CR, Cellusoft AP, Novozymes 342, Cellusoft L, Accelerase 1500). The added amount of each enzyme preparation corresponded to 150 FPU/100 g paper. It was observed that the deinking experiments using enzymes achieved generally better results in comparison with those in which the enzymes were previously deactivated. Despite the positive effect of activated enzymes as compared to deactivated, the application of enzymes appeared disadvantageous compared with the conventional deinking in terms of specks surface of the deinked paper sheets. Apart from the type of enzyme preparation itself, another critical factor affecting the effectiveness of the enzymatic treatment was the addition of nitric acid used to achieve acidic conditions for the optimum enzyme function. To this end, further study have to be performed on enzyme preparations functioning under alkaline conditions as well as on other paper types while the effect of enzyme amount to the deinking and the subsequent impacts on mechanical strength of produced papers may be also investigated.