ملیحه امینی

The objective of this paper is to remove phosphorus removal from a dairy wastewater in a batch system with simultaneous aerobic and anaerobic process. The system consists of a granular sequencing batch reactor (SBR) working under alternating aerobic/anaerobic conditions. In order to analyze the process, four significant variables viz. MLSS, COD/N ratio, aeration time and cycling time and four dependent parameters as the process responses were studied. The experiments were designed using a central composite design (CCD) and the data was processed under response surface methodology (RSM). The optimal removal percentage of PO43- obtained 98.34% at SVI, MLSS, and MLVSS of 44.03 ml/g, 5645.97 mg/l and 4435.99 mg/l, respectively. High-magnification SEM showed the morphological diversity of the microorganisms that inhabited the SCNP (Simultaneous carbon, nitrogen and phosphorous removal) in batch conditions, which included spherical, rod and long filamentous-shaped bacteria microorganisms. This study showed a successful high phosphorus removal from dairy wastewater with microbial granules cultivated under the alternating aerobic–anaerobic conditions in batch regime.