چكيده به لاتين
Water and wastewater treatment is one of the most important problems, especially in the arid region of the Middle East. Among the technologies used for water and wastewater treatment, membrane technologies are of particular importance. Meanwhile, Membrane Bioreactor (MBR) is one of the leading processes in the field of industrial and urban wastewater treatment, in which the organic load of the wastewater is consumed by microorganisms and finally filtered by the membrane to produce high-quality water, suitable for agricultural uses. On the other hand, the Forward Osmosis (FO) process is a new approach that allows to reduce water salinity by using osmotic pressure with low energy consumption. By combining MBR and FO technology, it is possible to introduce the Osmotic Membrane Bioreactor (OMBR) process, in which wastewater treatment and desalination are simultaneously possible at the same time. In this process, a membrane with a selective layer is placed inside the bioreactor, through which the treated water moves into the draw solution. In this way, both the effluent is treated with minimum energy and the draw solution, which can be sea water or concentrated RO flow, is diluted and treated with less energy thorugh forward osmosis. In general, the osmotic membrane bioreactor is introduced as the pre-treatment of the reverse osmosis unit, in which the configuration of the membrane can altered as one of the followings: the active layer facing the bioreactor (AL-FS) and the active layer facing the draw solution (AL-DS). Considering the microbial nature of the bioreactor, the AL-FS orientation is usually used, where there is less fouling, but in contrast, the concentration polarization of the salt inside the porous medium of the support layer causes a decrease in the osmotic pressure as the driving force. In this research, by using pure and modified antimicrobial silver nanoparticles, the anti-niofouling property was added to the support membrane, and in a new step, the selective layer was synthesized on the inner wall of the membrane. In this approach, it was possible to use the maximum osmotic pressure as the driving force and membrane fouling was decreased. In the osmotic membrane bioreactor process, the membranes were able to remove COD by more than 98%. Also, in further investigation, the amount of removal of nitrate and phosphate reached more than 98 and 96%, respectively. In studies of osmotic membrane bioreactor, the focus has always been on wastewater treatment, while in this research, reducing the salinity of the draw solution was also considered. In this way, a new parameter as Specific Performance Index (SPI) was introduced, which showed the ability of the membrane bioreactor process to reduce salinity. This parameter showed that the PES/Ag.Thl-PVP membrane with SPI of 778.2 g.l-1.m-2.h-1can transfer 1 m3/h flow from TDS equal to 58000 mg/l to mg/l with 50 m2 area. l will reach 20000 and this means reducing energy consumption in reverse osmosis from 61 bar pressure and 14.32 kWh/m3 energy consumption to 17.8 bar pressure and as a result, 4.18 kWh/m3 energy consumption.
