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 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.
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