D Domestic wastewater is one of the major sources of water pollution in indonesia; therefore, an effective treatment technology is required to reduce organic matter concentrations before wastewater is discharged into the environment. this study aimed to evaluate the performance of a moving bed biofilm reactor (mbbr) using kaldnes k5 carrier media and to analyze substrate removal kinetics under hydraulic retention times (hrts) of 8, 6, and 4 hours. the study consisted of influent wastewater characterization, reactor preparation, microbial seeding, acclimatization, continuous operation of a 1000 l mbbr system, and kinetic analysis using first-order, second-order kinetic models, monod kinetic models, and stover–kincannon kinetic models. the optimum hydraulic retention time was obtained at 4 hours, resulting the lowest effluent concentrations of 54.14 mg/l for chemical oxygen demand (cod), 25.53 mg/l for biochemical oxygen demand (bod), and 22.00 mg/l for total suspended solids (tss), with corresponding removal efficiencies of 85%, 88.89%, and 91.06%, respectively. the treatment performance demonstrated that the effluent concentrations of bod and cod complied with the effluent quality standards specified in appendix 1a no. 2 of the regulation of the minister of environment/environmental control agency of the republic of indonesia no. 11 of 2025 which regulates wastewater quality standards, wastewater treatment technology standards, and domestic wastewater. substrate utilization kinetics were evaluated using first-order, second-order kinetic models, monod , and stover–kincannon kinetic models. among these models, the second-order kinetic model provided the best fit to the experimental data, with utilization rate constants (k) of 1.56 day⁻¹ for cod and 1.16 day⁻² for bod.