Enhanced production and biodeinking application of β-glucosidase from Aspergillus niger S1 via submerged fermentation using office paper waste through conventional and statistical approaches

β-glucosidases are highly versatile catalysts with significant potential in various industries, including wastepaper deinking, which is a sustainable alternative due to its high effectiveness and minimal environmental impact. In this study, the optimal conditions for using submerged fermentation (SmF) to produce β-glucosidase from a newly isolated soil fungal species (Aspergillus niger S1) were improved. The main variables that influence the formation of β-glucosidase were examined, including temperature, pH, incubation period, nitrogen source, emulsifier concentration, and carbon source concentration. The production of β-glucosidase by the recently isolated Aspergillus niger S1 using office paper waste (OPW) as feedstock is encouraging because it reached its maximum production after just 3 days of incubation at pH 6.5 and 30 °C with office paper waste (15 g/L) serving as a carbon source at 1.5% (w/v), Tween 80 at 1.5% (v/v), and yeast extract as a nitrogen source. Using the CCD-based optimization approach, an enzyme yield of 3.35 U/mL β-galactosidase was achieved after 3 days of incubation at pH 6.0, with 1.5% (w/v) office paper waste and 1 g/L yeast extract. It was confirmed by the results that the β-glucosidase activity eliminated the ink particles and that this action improved the ash content, whiteness, and tensile strength. The findings showed that the investigated enzyme was a suitable green substitute for office paper waste deinking in the direction of sustainable waste management.