Enzymatic Hydrolysis of Old Corrugated Cardboard (OCC) Fines from Recycled Linerboard Mill Waste Rejects

During the manufacture of linerboard from recycled OCC (old corrugated cartons) , a significant fraction of the fibers are broken into small fine particles. These fines are rejected into the solid waste stream placing a cost for landfilling and posing environmental problems. The fines rejects are composed primarily of cellulose which can be hydrolyzed into sugars for possible fermentation into biofuels or other products. These fines have some advantages such as low cost and without any necessity of complex pretreatment processes characteristic to reduce lignocellulosic biomass. The enzymatic hydrolysis of reject fines from a recycled OCC mill was studied for producing sugars and the methods of reducing costs were considered. Three commercially available enzyme mixtures were tested. Cellulase from Trichoderma Reesei was found to be the most effective at loading levels of  5 – 100 FPU (/g of oven dry mass). The maximum hydrolysis yield was 45% sugar (g/g-OD fines) with 50 FPU. Since the fines rejects contain fillers (upto 30% by mass) , the enzyme loading was lowered by using surfactants to cover the mineral surfaces. Reductions of the enzyme dosage were observed to obtain high hydrolysis yield using non-ionic surfactants (Tween 80 , CTAB) or different pH buffer. As a result , Tween 80 reduced enzyme requirement to 30 FPU and Combination Tween 80 and pH 4 sodium acetate buffer increased efficiency of low enzyme dosage.