Effective bioremediation of pulp and paper mill wastewater using Bacillus cereus as a possible kraft lignin-degrading bacterium

•LiP, MnP, and laccase-producing B. cereus was discovered from mill sludge.•Observation of 89% KL degradation and 40% color reduction within 3 days.•SEM-EDS and FTIR analysis revealed interactions between bacterial cells and KL.•Treated effluent exposure reduced the phytotoxicity of T. foenum-graecum L. The effective degradation of KL from paper mill effluent is an important for environmental safety. This research is primarily concerned with the identification of KL-degrading Bacillus cereus from activated sludge and their possible use for the degradation of Kraft lignin (KL). This strain was involved in the production of lignin peroxidase-LiP (3.20 U/mL), manganese peroxidase-MnP (20.36 U/mL), and laccase (21.35 U/mL) enzymes, which were responsible for high KL degradation (89%) and decolorization (40%) at 1000 mg/L KL in 3 days. The SEM-EDS, UV–Vis, FTIR, and GC–MS analysis were used to analyze the bacterial cell and KL interactions to trace the KL degradation process. The significant reduction of pollutants (KL-72.5%, color-62.0%, COD-45.05%) and reduction in toxicity (80%) of bacterial-treated effluent indicated that B. cereus has the potential to be used in the degradation of pollutants from paper mill effluents.