Experimental study on the processes and mechanism of enhanced denitrification by addition zeolite in wastewater treatment

Aim to enhance nitrogen removal from wastewater, addition zeolite to aeration tank was preformed. The result showed that addition of zeolite could improve the nitrification/denitrification efficiencies by comparing two phase experiment of 25 mg/L with blank and 25 mg/L with 50 mg/L, and the population of nitrifying bacteria in activated sludge increased obviously. When 25 mg/L zeolite was added into aeration tank, NH₄⁺-N and TN removal increased 10%-13% and 13% respectively, endogenous respiration rate of nitrification increased about 138%, and the population of nitrification bacteria increased about 2.2 folds. But the nitrogen removal and endogenous respiration rate of 50 mg/L enhanced indistinct comparing with 25 mg/L. These results indicated that NH₄⁺ ion-exchange and accumulation to the interior/outer surfaces of zeolite, co-existence of aerobic and anoxic micro-environments were responsible for the enhanced denitrifying function.