Modelling the biological processes of MBR treatment plants

The paper proposes the use of a new mathematical model to simulate the biological processes taking place in membrane bioreactors (MBR) treatment plants. The model adopts the easy-to use matricial formulation of traditional activated sludge models (ASM). It couples the death-regeneration hypothesis of ASM 1 with the storage approach of ASM 3 in order to take into account the alternation of nutrients abundance and shortage periods, which are characteristic of treatment plants operating with low food/biomass ratio, as typically MBRs are. Moreover, it considers the production and the consumption of soluble microbial products, which play a fundamental role in biological membrane fouling. Model's parameters are either measured through respirometric tests, or obtained through calibration on a pilot-scale plant, and successive validation on a full-scale plant. The model is limited to the biological phases, and therefore it can be coupled with any detailed model of the separation phase, resulting in very versatile practical uses.