Green ecofriendly bio-deinking of mixed office waste paper using various enzymes from Rhizopus microsporus AH3: efficiency and characteristics

Mixed office waste paper (MOWP) is a low cost, high quality and easily collected fiber source for the papermaking industry. Unfortunately, limits in the application of traditional deinking are related to the negative environmental impacts of using chemicals during the deinking process. Hence, enzymatic deinking has received growing attention in the last decade. This study investigates the effect of using the effective enzymes produced from Rhizopus microspores AH3 which is grown on watermelon peel waste (WPW) extract, as a bio-deinking method in the deinking of MOWP, which is difficult to recycle because of their ink type and printing process. The methodology involves preparation of samples, impregnation with water, enzymatic treatment, washing, papermaking, evaluation of the produced paper sheets. The evaluation includes determination of the optical and mechanical properties as well as topographic investigation via scanning electron microscope of produced paper sheets. The results showed that there is an improvement in both optical and mechanical properties of all paper sheets produced in this study. The best enhancement was for medium B30 which was extracted by boiling of WPW for 30 min. This treatment gave high enhancement because of the effect of the produced enzymes from Rhizopus microspores AH3, where cellulase, xylanase, lignin peroxidase, poly phenol oxidase and laccase were 1.62, 1.49, 1.38, 1.2 and 1.5 U/ml, respectively. Moreover, the tensile strain (maximum load) increased by about 77% as well as the brightness percentage achieved about 86.78% and the deinking ability was increased approximately 16%.