Use of ion exchange for removal of Ammonium: A biological regeneration of zeolite

Nitrogen in the Ammonia form can have deleterious effects in water resources. Ion Exchange
by zeolite and biological Nitrification processes are two proposed methods for removing
Nitrogen compounds from wastewater and effluents. The main objective of this research was
to investigate the efficiency of nitrifying bacteria for regenerating Clinoptilolite zeolite.
In this research, the Semnan Clinoptilolite zeolite was supplied in mesh 30. Then the capacity
of zeolite in ammonium removal was determined in column system.
To cultivate of nitrifying bacteria a sludge sample was taken from a domestic wastewater
treatment plant and added to a 15 l aeration tank. Ammonium and other nutrients were added
in the reactor daily over a month period and the effect of nitrate anion and MLVSS on
nitrification process have been determined. After saturation of zeolite with ammonium,
biological regeneration was done by contact of zeolite and nitrifying bacteria in column
system. In this stage slurry of nitrifying bacteria is pumped up flow through the zeolite column
and recycled to the aeration tank. The effluent containing the displaced ammonium is oxidized
to nitrate by the nitrifying bacteria. Then the nitrified brine is clarified in a sedimentation tank
and stored for reuses.
The results showed that the cation exchange capacity was 10.06 (in breakthrough point) and
18.38 mg NH4+ g-1 zeolite as total capacity. The results indicated that nitrification accelerated
by increasing in MLVSS concentration and concentration of nitrate remains in solution. The
results obtained from bioregeneration tests of zeolite showed that the efficiency was 87.7 to
99.8% in period of 3.5 to 5.5 hours.
Based on the results, since regeneration is achieved in high concentration of nitrate, the use
of nitrifying sludge in several cycles is possible and the use of system can be appreciated to
an alternative economical method for removing NH4+ from effluent.