Research
| Title： | Microalgal dewatering using a polyamide thin film composite forward osmosis membrane and fouling mitigation |
|---|---|
| First author： | Ye, Jing; Zhou, Quan; Zhang, Xuezhi; Hu, Qiang |
| Journal： | ALGAL RESEARCH-BIOMASS BIOFUELS AND BIOPRODUCTS |
| Years： | 2018 |
| DOI： | 10.1016/j.algal.2018.02.003 |
| Abstract： | In this study, the dewatering of Scenedesmus acuminatus suspensions using a polyamide thin film composite (TFC) forward osmosis (FO) membrane with enhanced surface shearing was investigated. The influence of the draw solution (DS) concentration and microalgal properties were studied, and a fouling mitigation method using mechanical shearing was developed. S. acuminatus suspension dewatering by the same FO membrane was repeated 8 times to test the membrane's recoverability and durability. The results showed that the membrane flux and the concentration of magnesium chloride DS presented a non-linear relationship. In addition, membrane flux did not increase once the DS concentration increased to 2 mol L-1, when serious fouling occurred. However, the membrane flux was significantly improved by mechanical shearing across the membrane surface. At shear rate of 4 (1000 rpm), a 2 mol L-1 MgCl2 solution resulted in an average flux as high as 25.9 L m(-2) h(-1) during the dewatering of a 1.0 g L-1 microalgal suspension. Microalgal cells and algogenic organic matter (AOM) were tested to determine the membrane fouling mechanism. The results showed that the microalgal cells and AOM resulted in 15.4% and 9.4% water flux loss in 1 h, respectively, whereas the combination of microalgal cells and AOM resulted in 24.7% water flux loss. After dewatering for 8 h, microalgal suspensions were concentrated 20 times, and the average membrane flux was 23.3 L m(-2) h(-1). In addition, most of the membrane fouling was reversible by simple hydraulic flushing; the pure water flux remained more than 97% of original pure water flux after 8 repeated dewatering processes, which demonstrated the potential application of FO in microalgal dewatering. |
