Background and Objectives: Aerobic sludge granulation is an advanced phenomenonin which its mechanisms have not been understood. Granulation can be a promising and novel biological wastewater treatment technology to eliminate organic and inorganic materials in future. High salinity is a parameter which leads to plasmolisatian and reduction of the cell activity. This could be a problem for biological treatment of the saline wastewater. Aerobic granule was formed and investigated during this study.
Materials and Methods: This study is an intervention study on the treatment of wastewater with 500-10000 mg/L concentration of NaCl by sequencing batch reactor. Asynthesized wastewater including nutrient required for microorganism's growth was prepared. Input and output pH and EC were measured. Range of pH and DO varied between 7-8, and 2-5 mg/L, respectively. SEM technology was used to identify graduals properties.
Results: In terms of color, granules divided into two groups of light brown and black. Granule ranged in 3-7mm with the sediment velocity of 0.9-1.35 m/s and density of 32-60 g/L.Properties of granules were varied. Filamentous bacteria and fungi were dominant in some granules. However non filamentous bacteria were dominant in others. EDX analysis indicated the presence of Ca and PO₄.
Conclusion: Granules with non filamentous bacterial were compact and settled faster. Presence of different concentrations of salinity leaded to plasmolysis of the bacterial cells and increased concentrations of EPS  in the system as a result  of which granulation accelerated.