Improvement of transport phenomena and COD removal through the design of manifolds in membrane aerated biofilm reactors for sewage treatment

The membrane aerated biofilm reactor (MABR) has demonstrated a huge potential in wastewater treatment plants (WWTPs) due to biofilm stratification and high oxygen transfer efficiency. However, an inappropriate design can negatively impact hydrodynamic and mass transfer, hampering the reactor performance. This work is intended to enhance these phenomena through a rational design of inlet flow distributors (IFD) using computational fluid dynamics (CFD) and mass-transfer simulations. Different IFDs are analyzed at macro and micromixing levels using the residence time distribution (RTD) test and CFD, respectively. It is found that the computed RTD curves agree with experimental data with an error <5 %. The conical wall distributor generates the most homogeneous velocity in the entire reaction zone (membrane zone). The maximum velocity ratio between the channeling and stagnant zones presents a diminution of ∼70 %, and an increment of ∼11.7 % on the chemical oxygen demand (COD) removal if compared against the MABR without IFD, during the sewage treatment. Results show an acceptable agreement of simulations and experimental data, indicating that this approach is satisfactory to conduct a rational design of this type of reactor.