The method employed in most membrane systems is stripping that employs a forced draft degasifier. This device uses a packed tower with counter current atmospheric airflow to strip the H2S out of the water. Note that this process will also remove any CO2 present while saturating the permeate with oxygen, thus exacerbating the inherent aggressive nature of this water. To effectively remove sulfide with this method, it must exist as H2S. Being pH dependent, this means that either acidification of the feed is done to achieve a permeate pH <6.0 or the permeate is acidified to this point to allow for >90 % removal.
Note that as the stripper concurrently strips the CO2 and does not affect the alkalinity, the pH of the water will increase as the water passes through the stripper. It is extremely important that the pH of the effluent remains <6.0. If the pH is allowed to rise, then the H2S will ionize to HS- which is soluble and will not air strip.
H2S(g)+ aq ---> H+(aq) + HS-(aq)
The off gas from the stripper will be odorous and should be run through a H2S scrubber as you may receive complaints.
It depends somewhat on the packing that is used as well as the liquid loading rate. If you are using 3.5-Inch Lanpac, at a water loading rate of 61 M3/M2-H, with an air flow rate of 0.5 M/S, then the differential pressure across the packing is 0.2 mbar/meter of packing for a total of 3 mbar.
