Self-forming dynamic membrane bioreactors (SFD MBR) for wastewater treatment: Principles and applications

Early scientific studies on membrane bioreactors (MBR) date back to the late 1980s. Since then, this technology has undoubdetly represented an important innovation in the field of biological wastewater treatment processes. However, 30 years of MBR application have shown some drawbacks of this technology. The main shortcomings of conventional MBR are the higher installation costs with respect to CAS, and higher management requirements, especially related to the need to contrast membrane fouling, that stands as the main weaknessof MBR operation. A possible strategy to cope with the above-mentioned drawbacks of MBR entails the adoption of filtration materials that are less expensive and simpler to handle, and require lower energy for process operation with respect to the commonly adopted polymeric membranes. A novel approach in this sense is represented by the development of "dynamic membranes" (DM). DM consists of "temporary" filtering layers composed of the solid particles born by the filtered solution, which tend to accumulate on a supporting surface made of relatively coarse material, and having pore size in the loose microfiltration range (tens of ?m). The present chapter provides an overview of the SFD MBR technology, illustrating the principles, the most relevant applications described in the technical literature, and the main factors influencing the process.