A novel Forward osmosis membrane pretreatment of seawater for thermal desalination processes
- 標題
- A novel Forward osmosis membrane pretreatment of seawater for thermal desalination processes
- 作者
- Ali Altaee, Abdelnasser Mabroukb, Karim Bourounic
- 文件屬性
- 國外期刊
- 知識分類
- 礦物質分離
- 出版年
- 2013
- 刊名
- Desalination
- 關鍵字
- FO membrane softening; Seawater pretreatment; Thermal desalination; Scale removal
- 點閱數
- 2549
摘要
The present work introduced a novel conceptual design of integrating Forward Osmosis (FO) membrane with the Multi Stage Flashing (MSF) or Multi Effect Distillation (MED) thermal desalination processes. A simple mathematical model was developed here to estimate the performance of the FO membrane system. A previously developed program, VDS, for estimating the performance of thermal processes was updated to include the FO system. The verified VDS program [1] was applied to simulate the performance of the FO–MSF/MED hybrid system at different recovery rates varied from 16% to 32%. Brine reject from the thermal desalination processes was recycled and used as a draw solution to reduce the cost of FO membrane pretreatment. Seawater was used as the donor solution in the FO membrane. The simulation results showed that the FO pretreatment, successfully, reduced the concentration of multivalent ions in the feed solution to the MSF and MED. It was found that the concentrations of Ca2 +, Mg2 +, and SO42 − ions, which are responsible for scale problem in MSF, decreased with increasing the recovery rate of FO membrane. In case of FO–MED hybrid system, the thickness of the CaCO3 scale layer was calculated at different FO recovery rates. The estimated thickness of CaCO3 scale layer was 74 μm, 43 μm, and 39 μm for 0%, 20%, and 32% FO recovery rate respectively. It was also found that the thickness of CaCO3 scale layer decreased in the direction from effect 1 to effect 6 due to temperature drop. Finally, the study demonstrated the feasible application of FO membrane in the pretreatment of seawater to reduce the concentration of multivalent ions which are responsible for the scale problem in the thermal desalination processes.