Alkaline enzyme assisted deinking of mixed office waste paper with cellulose

The enzymatic deinking process was developed in two stages, the first one was the enzyme pretreatment and the second one the subsequent flotation deinking, both conducted at pH = 5.5 and temperature = 55°C. Other process parameters were: enzyme concentration = 1545.96 FPU, air flow rate of 0.5L/min, and Na₂SiO₃ concentration of 48.65 Be. The optimal deinking conditions were: Enzyme dosage of 0.15%, enzymatic action time of 20 min, flotation consistency of 0.5%, whereby the 70% of essays reached ISO brightness over 70%, with a maximum value of 80% and an average yield of 90%.