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

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Bioreactor Design

Background:

• Wastewater treatment often requires advanced methods for nutrient removal.
• Anaerobic digestion, like the Up-flow Anaerobic Sludge Blanket Reactor (UASB), partially treats sewage but leaves residual nutrients.
• Efficient removal of ammonium-nitrogen (NH4-N) and phosphate-phosphorus (PO4-P) is crucial for preventing eutrophication.

Purpose of the Study:

• To evaluate the efficacy of a plug flow multimedia reactor (PFMMR) for removing NH4-N and PO4-P from UASB-treated sewage effluent.
• To investigate the treatment performance over a 105-day period using plastic carriers and activated carbon as media.
• To assess the applicability of kinetic models (Stover-Kincannon, Grau, Monod) for nutrient removal in the PFMMR.

Main Methods:

• Utilized a plug flow multimedia reactor (PFMMR) with plastic carriers and activated carbon.
• Treated effluent from an Up-flow Anaerobic Sludge Blanket Reactor (UASB) over 105 days.
• Applied Stover-Kincannon, Grau, and Monod models to determine kinetic coefficients for NH4-N, COD, and PO4-P removal.
• Characterized biomass growth using Fourier Transform Infra-Red (FTIR), Dynamic Light Scattering (DLS), and Scanning Electron Microscopy (SEM).

Main Results:

• Achieved high removal efficiencies: 91.2% for NH4-N and 31.0% for PO4-P.
• Identified strong positive correlations between UASB and PFMMR COD effluents and between sewage and UASB NH4-N.
• The Monod model proved most suitable for assessing nutrient concentrations, with low Umax and high Kd values indicating efficient removal.

Conclusions:

• The PFMMR system effectively removes COD, NH4-N, and PO4-P from anaerobically treated sewage.
• The Monod model accurately describes the kinetics of nutrient removal in the PFMMR.
• Biomass characterization confirmed successful cultivation on the multimedia, supporting the reactor's performance.