عنوان مقاله [English]
MBBR is a combination of three systems: Activated sludge, Fixed film, and Fluidized bed. This system has been designed in a manner to include the advantages of the above systems but removing most of their disadvantages. The main characteristic of the system is the growth of a biofilm on the small packing that moves through the reactor. Because of the biofilm growth on the kaldnes packing, the internal special area of the MBBR is high and around 350 m2/m3. Evidenced by reports in the literature, MBBR has been successfully used for the treatment of different industrial effluents from dairy industries, food industries, slaughter houses, paper mills, refineries, and chemical plants. In this study, the operation of MBBR in treating the combined municipal and industrial wastewater (Parkand Abad Wastewater Treatment Plant, Mashhad, Iran) is studied. The results from the pilot study revealed that MBBR was capable of reducing COD levels to 43, 57, 76% at such low hydraulic retention times of 8, 12, 24 hrs, respectively. The system was also found to be capable of handling hydraulic shocks such that the system regained its stability over a short time after the shock and that the effluent COD fluctuation before and after the shock was as low as 70 mg/l.