Dead-end and tangential ultrafiltration of natural salted water: Influence of operating parameters on specific energy consumption

The present study deals with the specific energetic consumption evaluation of dead-end and tangential ultrafiltration (UF) (100 kDa) of salted suspensions on polysulfone membrane in regards of backwash and aeration conditions. For TMP ranging from 0.2 to 0.8 bar, it was found that specific energy consumption during tangential UF was always higher than in dead-end mode. During dead-end UF at 0.4 bar with a backwash frequency equal to 15 min, the 30 s backwash duration allowed obtaining the highest net permeate flux (27 L h−1 m−2) and the lowest specific energy consumption (146 Wh m−3). Changing the backwash frequency to respectively 5 or 60 min did not induce lower energy consumption. The bubbling located at the bottom of fiber bundle accounted for more than 68% of the total specific energy consumption and enhanced the net permeate flux only in the presence of backwash. During the UF at 0.4 bar with 30 s and 15 min of backwash time and frequency respectively, the total energy consumption appeared lower (35 Wh m−3) without bubbling. Finally, the lowest specific energy consumption (16 Wh m−3) was obtained for dead-end UF at 0.4 bar without backwashing or bubbling; in these operating conditions, stabilized net permeate flux was equal to 16 L h−1 m−2.