Performance, Kinetics and Correlation Study of a Plug Flow Multimedia Reactor Treating Conventional UASB Effluent

The present study aimed to remove nutrients from anaerobically treated effluents using a plug flow multimedia reactor (PFMMR). An Up-flow Anaerobic Sludge Blanket Reactor (UASB) was used for sewage treatment. This study was conducted for 105 days to investigate the removal of NH₄–N and PO₄–P from the UASB effluent treating sewage through denitrification using a plastic carrier and activated carbon as a medium in the PFMMR. The results indicated that the removal efficiencies of NH₄–N and PO₄–P reached 91.2% and 31.0%, respectively. Correlation analysis revealed that the most robust positive correlations were between UASB and PFMMR COD effluents (0.614) and between sewage and UASB NH₄-N (0.657), signifying consistent treatment behaviors for these parameters. The “Stover–Kincannon” Grau and Monod models were used to assess the kinetic coefficients for the removal of NH₄–N, COD, and PO₄–P in the PFMMR. The results revealed that the Monod model was the most appropriate and applicable for assessing nutrient concentrations. The PFMMR system was able to remove COD, NH₄–N, and PO₄–P with high removal efficiency, as shown by the low U_max and high K_d values. In addition, the specific growth of biomass cultivation on the multimedia was characterized by Fourier Transform Infra-red (FTIR), Dynamic light scattering (DLS), and Scanning Electron Microscopy (SEM) methods.