TY - JOUR
T1 - Impact of osmotic backwashing, particle size distribution and feed-side cross-flow velocity on flux in the forward osmosis membrane bioreactor (FO-MBR)
AU - Nawaz, Muhammad Saqib
AU - Parveen, Fozia
AU - Khan, Sher Jamal
AU - Hankins, Nicholas P.
N1 - Funding Information:
The authors acknowledge the financial support for this research work provided by the INSPIRE program, which is jointly funded by the Higher Education Commission (HEC) of Pakistan and the British Council (BC) (Project No. SP-192). The authors also acknowledge Hydration Technology Innovations (HTI) Albany, for providing cartridge FO membranes for this study. The authors are also very grateful to the Singapore Membrane Technology Center (SMTC), at Nanyang Technological University, for providing a fabricated hollow fiber membrane module for this study.
Funding Information:
The authors acknowledge the financial support for this research work provided by the INSPIRE program , which is jointly funded by the Higher Education Commission (HEC) of Pakistan and the British Council (BC) (Project No. SP-192 ). The authors also acknowledge Hydration Technology Innovations (HTI) Albany, for providing cartridge FO membranes for this study. The authors are also very grateful to the Singapore Membrane Technology Center (SMTC), at Nanyang Technological University, for providing a fabricated hollow fiber membrane module for this study.
Publisher Copyright:
© 2019 Elsevier Ltd
PY - 2019/10
Y1 - 2019/10
N2 - The application of the forward osmosis membrane bioreactor (FO-MBR) requires further investigation in the area of process optimization. In current study, different operational parameters for improving the overall efficiency of FO-MBR were studied and optimized in batch and semi-continuous experiments. The effect of osmotic backwashing, cross-flow velocity of the feed solution (activated sludge), and particle size were studied on the FO-MBR flux. All batch experiments were of 8 h duration, comprising 7 h filtration and 1 h osmotic backwash. It was found that osmotic backwashing was ineffective for complete flux recovery in a hollow fibre FO-MBR, due to severity of the fouling caused by the activated sludge feed in ‘active layer facing draw solution’ mode. A slightly better recovery was observed however with a single 60 min backwash as compared to 2 backwash cycles of 30 min each or 3 backwash cycles of 20 min each. A cross-flow velocity of 0.105 m/s proved optimum. Higher velocities caused a breakdown of flocs and reduced the mean particle size, the latter resulting in lower water flux. Similarly, lower cross flow velocities were not able to provide effective membrane scouring, resulting in lower water flux. The particle size decreased with operational time in the FO-MBR. It was also established that, above the optimum cross flow velocity, flux is inversely proportional to the difference between the initial and final particle size of sludge.
AB - The application of the forward osmosis membrane bioreactor (FO-MBR) requires further investigation in the area of process optimization. In current study, different operational parameters for improving the overall efficiency of FO-MBR were studied and optimized in batch and semi-continuous experiments. The effect of osmotic backwashing, cross-flow velocity of the feed solution (activated sludge), and particle size were studied on the FO-MBR flux. All batch experiments were of 8 h duration, comprising 7 h filtration and 1 h osmotic backwash. It was found that osmotic backwashing was ineffective for complete flux recovery in a hollow fibre FO-MBR, due to severity of the fouling caused by the activated sludge feed in ‘active layer facing draw solution’ mode. A slightly better recovery was observed however with a single 60 min backwash as compared to 2 backwash cycles of 30 min each or 3 backwash cycles of 20 min each. A cross-flow velocity of 0.105 m/s proved optimum. Higher velocities caused a breakdown of flocs and reduced the mean particle size, the latter resulting in lower water flux. Similarly, lower cross flow velocities were not able to provide effective membrane scouring, resulting in lower water flux. The particle size decreased with operational time in the FO-MBR. It was also established that, above the optimum cross flow velocity, flux is inversely proportional to the difference between the initial and final particle size of sludge.
KW - Cross-flow velocity
KW - Osmotic backwashing
KW - Particle size distribution
KW - Process optimization
UR - http://www.scopus.com/inward/record.url?scp=85066761040&partnerID=8YFLogxK
U2 - 10.1016/j.jwpe.2019.100861
DO - 10.1016/j.jwpe.2019.100861
M3 - Article
AN - SCOPUS:85066761040
SN - 2214-7144
VL - 31
JO - Journal of Water Process Engineering
JF - Journal of Water Process Engineering
M1 - 100861
ER -