MHC bioregeneration
Donnan dialysis coupled with bio-denitrification was used to regenerate
MHC. Before bioregeneration, MHC was saturated by
NO3--N in
repeated
coagulation processes. Then the bioregeneration was carried out at room
temperature and under anaerobic conditions in a Donnan dialysis setup.
The setup was made of Plexiglas (Beijing, China), divided into two
chambers by a JAM-I homogeneous anion exchange membrane. The spent MHC
was added into the desorption chamber. Sludge, 0.3 mol/L NaCl, and 12.9
mol/L ethanol (as carbon source) were added to the stripping chamber.
The solution pH in both chambers was adjusted to 7.0 ± 0.2. The solution
was stirred continuously at 400 rpm. Throughout the 30 h regeneration
process, samples were collected at regular intervals from both chambers
and filtered through 0.22 μm nylon membranes for analysis of residual
NO3--N. The sludge cultivation method
is in the SI.