Modelling of moving bed biofilm reactor (MBBR) efficiency on hospital wastewater (HW) treatment: a comprehensive analysis on BOD and COD removal

Performance of moving bed biofilm reactor system for a real hospital wastewater (HW) was experimented, modelled, and optimized using response surface methodology. Prior to conducting laboratory tests, design of the experiments was evaluated to minimize any prediction error. Statistical analyses demonstrated the models’ validity and adequacy for anticipation of the removal of BOD and COD by the process. The models predictions (with desirability of 0.98) were found to be in very good agreement with confirmative experiments results. The results indicated that under convenient operating conditions of the studied variables (packing rate 70%, HRT 24 h, and MLSS 3000 mg/L), the removal efficiencies for BOD and COD were 97.8 and 95.6%, respectively. Moreover, kinetics of the biological process showed that removal of organic matters for the tested wastewater adheres to modified Stover–Kincannon model with a correlation coefficient of 0.998. Ratio of BOD to COD of 0.6 (optimal range for biological treatment normally is >0.5) suggests acceptable efficiency of the reactor for decomposing organic load. A high overall efficiency of the process and fulfilling the related standards make this system an appropriate option for treating HDW.