A model for wastewater organic removal and fouling development in a SMBR pilot plant

The paper presents the setting up of a mathematical model for membrane bioreactor able to simulate physical-biological wastewater organic removal. The model is basically divided into two sub-models: the first sub-model is basically devoted for the simulation of the biological features and the second one for the physical processes. In particular regarding the biological aspects, the ASM concept has been employed. On the other hand, the physical processes have been modelled considering the deep-bed theory taking into account not only the effect of the physical membrane filtration but also the cake layer effect. This latter operates as a biological membrane leading to a further reduction of the effluent COD. The model was applied to a SMBR pilot plant characterized by hollow fibre membrane module in submerged configuration. The SMBR was fed by raw wastewater, only screened with a sieve of 2 mm, collected from the Palermo (IT) WWTP. The SMBR was characterized by an operating volume of 190 litres and it was equipped with an aeration system located on the bottom of the reactor. The whole experimentation was divided in two subsequent experimental phases: a former one where, the SMBR pilot plant started-up was carried out without inoculum of activated sludge, and a second one considering the inoculum. The pilot plant was in operation for a total period of 130 days. The model results are interesting and confirm the importance of cake deposition in the filtration process. The developed model can be employed as a useful tool in optimizing operation conditions as well as design parameters for SMBR systems.