The paper highlighted the potential of superfast membrane bioreactor (SFMBR), as novel process configuration for biological treatment. SFMBR was essentially based on extremely high rate system operation at sludge ages between 0.5 and 2.0 d. It also reflected an innovative concept relying on partial COD removal, which enabled optimal disposal and reuse of excess COD and sludge with energy recovery options, while generating an effluent suitable for reuse within a smaller possible footprint. Studies showed that SFMBR proved capable of securing complete removal of soluble biodegradable COD, even at extremely high concentrations of 1,000mg/l. It also generated much lower soluble microbial products, partly retained and accumulated in the reactor. Phylogenic analyses indicated that operating conditions affected the composition of the microbial community; results confirmed the existence of a functional relationship between variable process kinetics and changes in the microbial community structure. The paper also presented an overview of traditional MBR approach leading the SFMBR concept, which was initially interpreted as a possibility to sustain high biomass concentrations and operate at excessively high sludge age levels. While this potential has been extensively used in practice for effective removal of organic carbon and nitrogen, research efforts mainly focused on the mechanism of simultaneous nitrification and denitrification; they explored functional relationships between biomass and diffusion limitations and defined operation schemes that would provide nitrogen removal without an anoxic reactor.