Two ammonium-tolerant yeast strains were isolated from sludge samples contaminated with monosodium glutamate manufacturing wastewater and were identified as Candida haplophila and Rhodotorula glutinis. The tolerance of the two yeast isolates to ammonia and their chemical oxygen demand (COD) removal performances were evaluated under batch and bench-scale conditions. The mixture of the two isolates was found to grow well in an artificial medium containing 25% (NH,) 2 SO 4 and could effectively remove COD from monosodium glutamate wastewater even when the concentrations of NH 4 +

By enriching the culture medium, three dominant bacteria(X1, X2 and X3) were selected from the farmland sludge. The degradation effect of X1, X2, X3 and mixed bacterium(X123) under different initial ammonia nitrogen(NH3-N) concentration, pH and C/N were studied under laboratory, the effect of X123 was compared with purchased bacteria(S1, S2 and S3) and strains in published literature. The results showed that X123 had the best effect when the initial NH3-N concentration was 20 mg·L−1, pH was 7 and C/N was 10, the degradation rate was 96.4% after 2 days of culture. Comparing X123 with S1, S2 and S3, it was found that X123 had the best effect. Comparing X123 with the strains in published literature, it can be seen that the difference for the degradation of NH3-N was very small, and the growth conditions of the strain were almost same. It was shown that X123 can effectively degrade NH3-N from wastewater, which has potential of application for treatment of nitrogen polluted wastewater.