
Water Science & Technology Vol 42 No 1-2 pp 179185 © IWA Publishing 2000
Ammonium removal from primary and secondary effluents using a
bioregenerated ion-exchange process
O Lahav* and M Green**
*
Faculty of Agricultural Engineering, Technion Israel Institute of
Technology, Haifa 32000, Israel
**
Faculty of Agricultural Engineering, Technion Israel Institute of
Technology, Haifa 32000, Israel
ABSTRACT
A new process for ammonia removal from sewage effluents is presented.
The process uses an ion exchange material, zeolite, both as the separator
of NH4+ from the wastewater and also as the carrier
for a nitrifying biomass. The process is carried out in a single reactor
operating in two modes: an adsorption mode in which the zeolite column acts
as a typical ion exchanger and a bioregeneration mode in which the bacteria
attached to the zeolite oxidizes the NH4+ to
NO3. The separation between carbonaceous
removal and NH4+ removal enables the exclusive
selection of nitrifiers at high concentrations attached to the zeolite,
thus achieving high bioregeneration rates. This paper summarizes three
years of research on the process and focuses on the operation with actual
secondary and primary effluents. Process operation showed: (1) no bed clogging occurred due to suspended solids accumulation; (2) residual BOD
from the adsorption phase resulted in only minimal heterotroph competition
and thus, no fall in the rate of bioregeneration; (3) only a small
deterioration in exchange efficiency due to zeolite biofilm coverage as
compared to the ion exchange efficiency of "virgin" zeolite.
Results show that both secondary and primary effluents can be successfully
treated by the process.
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