LAUSR

Abstract The wastewater containing the azo dye is a global environmental challenge among researchers. In this study, an effort has been made to use a modified carrier (i.e., low-density polyethylene-polypropylene (LDPE-PP)) to remove the Congo red (CR) dye from synthetic wastewater in a moving bed biofilm reactor (MBBR). The effect of CR dye concentration (25 to 300 mg/L), hydraulic retention time (HRT) (12 to 96 h) under the batch mode, and inlet loading rate (ILR) (40 to 320 mg/L.day) under the continuous mode were examined. The highest removal efficiency (RE) and elimination capacity (EC) of CR dye were obtained as 99.2% and 214.4 mg/L.day, respectively. Three models, namely first-order, Grau second-order, and modified Stover-Kincannon (S-K) were applied to study the kinetic aspects. The highest correlation coefficient ( R 2 ) was obtained for the modified S-K model, and the saturation constant ( K B ) and maximum substrate removal rate ( U m a x ) were estimated as 0.67 g/L.day and 0.71 g/L.day, respectively. The proposed kinetic equations can predict the effluent concentration and estimate the bioreactor volume to scale up the process.