Abstract:
Freshwater algal blooms negatively impact the operations of water treatment plants when they are present in the
source water. In the present study, an application of a low-cost submerged microfiltration membrane bioreactor
for the removal of microalgae from a source water reservoir of a water treatment plant was evaluated. The
experiments were conducted in different phases to systematically evaluate how different fouling control methods
such as air scouring and water backwashing in combination with vibration technique can enhance the flux and
removal efficiency of microalgae in a submerged flat sheet microfiltration membrane bioreactor. Combining
backwashing with air scouring (Phase 3) positively enhanced the flux by reducing the TMP, but it did not
improve the permeate quality in terms of microalgae and turbidity removal. The results of Phase 4 studies
confirmed that vibration had a profound effect on microalgae removal compared to backwashing technique
while reducing the TMP from 105 to 103 kPa. The average turbidity removal was increased from 76.75% to 82%
when vibration is applied. Combining all fouling control methods such as air scouring, backwashing and vibration methods did not appear to be effective for the removal of microalgae and turbidity (Phase 5). In order to
signify the energy input on membrane fouling control, flux in each phase was assessed with respect to total power
input. In overall, air scouring at a rate of 7 L/min with 50 Hz of vibration appeared to be an optimum condition
in controlling fouling without any frequent backwashing.
