This study estimated the ability of pressurization to collapse gas vesicles and thereby enhance the settleability of fresh water cyanobacteria. Settling velocities of Pseudanabaena galeata and Microcystis aeruginosa were measured at 11 different pressure values from 0 to 0.5 MPa. The morphological variations that occurred in the gas vacuoles according to the applied pressure were investigated using transmission electron microscopic images. The settleability of both cyanobacteria species statistically significantly (P = 0.000) increased with increasing pressure, whereas the gas vacuolated area of both species decreased significantly (P = 0.000) with the magnitude of the applied pressure. The removal ability of cyanobacteria cells from water layer increased with high pressure treatment. The maximum removal efficiency relative to the control culture observed of P. galeata and M. aeruginosa cells were 82% and 95%, respectively, at the maximum tested pressure value of 0.5 MPa.
- First received 16 December 2015.
- Accepted in revised form 12 April 2016.
- © IWA Publishing 2016