The introduction of cleaner technologies through the reuse of wastewater for energy recovery can improve the environmental performance of leather industries. The polluting effects of wastewater from tanneries can be minimized by treatment of tannery effluent prior to discharge to the environment. The biological treatment method is cost effective and environmentally friendly than physicochemical treatment method. Anaerobic digestion of tannery wastes is an attractive method to recover energy from tannery wastewater. The anaerobic digestion of tannery wastewater produces biogas, a valuable energy resource which consist of Primarily methane (CH4) & carbon dioxide (CO2). The objective of this study was to develop a laboratory scale anaerobic sequential batch reactor (ASBR) which utilizes composite tannery wastewater at mesophilic (37℃±2) system to generate biogas and enhance the production of methane and biogas production by using nanoparticles of Iron oxide (Fe3O4) MNPs as a catalyst. For this purpose, 1L glass bottle bio digesters were used. Four different concentrations of Fe3O4 MNPs (20ppm,50ppm, 75ppm and 100ppm) and one control (without MNPs) totally five biodigester was prepared. The HRT hydrolysis/acidification was 3 days and the OLR was wide-ranging between 0.85 to 1.095 kg COD/m3-day throughout the study. It was observed that 75mg/L recorded maximum specific methane yield (0.33L/g COD) and followed by 50mg/L (0.31L/g COD). The highest volume of biogas also recorded at 75mg/l of iron oxide (Fe3O4) MNPs which was (1620ml) and content of methane (70.1%) followed by 50mg/l NPs which was biogas volume (1520ml) methane content 60.7%). The removal efficiency of total solid and volatile solid of all digesters was in the range of 56.2-75.5% and 65.1-84.5 %, respectively. The remaining recorded better performance than the control (With out NPs). The results of this experiment proved that treatment of ASBR that utilizes composite tannery wastewater with iron oxide (Fe3O4) MNPs advances the quality, quantity of biogas and the removal efficiency of COD, TS, VS under mesophilic temperature e (37℃) condition.