Development Of Solid State Fermentation System For Enzyme Production And Its Usage In A Pilot Scale Deinking Of Printed Waste Paper

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Date
2010-12
Authors
Lee, Chee Keong
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The present work deals with the development of solid state fermenter for enzymes production and the development of a pilot scale of enzymatic deinking system. The newly developed solid state fermenter, was named FERMSOSTAT®, which was used for the production of cellulases and xylanase using a local isolate; Aspergillus niger USM AI 1. Optimization of enzymes production was carried out and the optimum conditions obtained were 0.5 kg substrate (a combination of PKC and sugarcane baggase at 1:1 ratio); 70% (w/w) moisture content; incubated at 30°C; aeration at 4.0 L/heg fermented substrate for 5 min and mixing at 0.5 rpm for 5 min. Under the optimum SSF conditions, the CMCase, xylanase and FPase activities obtained were 62.6 U/g, 390.8 U/g and 3.4 U/g, respectively. This represents about 9.6, 7.8 and 3.4 folds increased in their respective enzymes activities after the optimization process. When comparative study on the enzymes production was performed using Trichoderma reesei, the CMCase, xylanase and FPase activities obtained were about 57.3 U/g, 563.0 U/g and 2.2 U/g, respectively. The enzymes produced were used in the deinking studies of mixed office waste paper (MOW) and old newspaper (ONP) using newly developed pilot scale enzymatic deinking system. Optimization of enzymatic deinking process was carried out and the optimum conditions obtained for MOW were pulping at 2% consistency for 60 min; enzymatic hydrolysis at 50°C, pH 5.5, 0.8 U of CMCase and 4.0 U of xylanase per gram of air dry weight of pulp and 60 min of hydrolysis time and flotation process at pH 8.0, 0.20% (w/w) of Tween 80 and 5 min of flotation time. Meanwhile, the optimum conditions obtained for the de inking of ONP were pulping at 3% consistency for 45 min; enzymatic hydrolysis at 50°C, pH 5.5, 0.4 U ofCMCase and 2.0 U ofxylanase per gram of air dry weight of pulp and 45 min of· hydrolysis time and flotation process at pH 8.0, 0.55% (w/w) of Tween 80 and 20 min of flotation time. The deinking efficiency obtained for MOW and ONP under their respective optimum conditions were about 6.0% and 6.3%, respectively. The deinking efficiency detected by chemical deinking of MOW and ONP were about 2.9% and 3.5%, respectively. Both enzymatic and chemical deinking processes not only significantly influence optical and mechanical properties of the deinked paper but also the pulp properties and the effluent generated. Enzymatic deinking of MOW showed improvement in brightness (4.7 units), tensile index (14.1%), burst index (3.4%), freeness (2.0%) and residual ink removal (44.5%) but decreased in opacity (2.6%) and tear index (9.6%). Meanwhile, enzymatic deinlcing of ONP showed improvement in brightness (2.5 units), tensile index (10.2%), burst index (3.8%), freeness (2.9%) and residual ink removal (51.15%) but decreased in opacity (0.4%) and tear index (3.9%). Unlike enzymatic deinking, chemical deinking of MOW demonstrated increased in the brightness (2.3 units), tensile index (1.1 %), burst index (1.2%), freeness (1.9%) and residual ink removal (31.1%) but loss in opacity (1.4%) and tear index (0.1%). Meanwhile, chemical de inking of ONP showed enhanced in brightness (1.4 units), tensile index (6.8%), burst index (3.0%), freeness (2.3%) and residual ink removal (49.8%) but decreased in opacity (0.1%) and tear index (1.1%). Biological oxygen demand (BODs) and chemical oxygen demand (COD) analysis indicated that, effluent produced from the enzymatic deinking process was lower compared to chemical deinking process. About 33.9% and 33.8% lower in COD values were obtained after enzymatic deinking ofONP and MOW compared to chemical deinking process, respectively. Meanwhile, BODs obtained from enzymatic deinking of MOW and ONP were 47.1% and 39.3% lower compared to chemical deinking process, respectively. This directly will reduce the wastewater treatment cost. In addition, based on the Malaysia Environmental Act 1974; no wastewater treatment was required on the effluent obtained from deinking of MOW, where the effluents obtained were within the pennitted value for safety discharged into the environment. The results obtained from this work suggested that the enzymatic deinking can be a highly potential alternative to the chemical method, which showed several problems and disadvantages compared to enzymatic deinking in the recycling of waste paper.
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Keywords
Solid State Fermentation System , Printed Waste Paper
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