Abstract:

This research aims to obtain bacterial that can effectively degrade wastewater containing ammonia nitrogen. 6 strains with degrading ammonia nitrogen ability were enriched and isolated from high ammonia nitrogen wastewater using plate isolation and streak purification techniques. These strains were subsequently inoculated into chicken manure wastewater with high ammonia nitrogen content. After 48 hours of cultivation, the ammonia nitrogen concentration was measured every 8 hours using the Nessler's reagent method to select the best ammonia nitrogen degradation strain. It’s showed that all the 6 strains could effectively reduce the ammonia nitrogen concentration in wastewater with an initial concentration of 3.19 mg/mL. The degradation process followed the Boltzmann curve model. After 48 hours treatment by strain N-1 to N-6, the ammonia nitrogen concentrations decreased to 2.48 mg/mL, 2.47 mg/mL, 2.49 mg/mL, 2.55 mg/mL, 2.37 mg/mL and 2.53 mg/mL, respectively. The average degradation efficiency was 14.79, 15.21, 14.38, 13.33, 17.08 and 13.54 mg/(L·h), indicating that the strain N-5 exhibited the highest degradation efficiency. Moreover, it had 99.13% similarity to strain Streptomyces griseorubiginosus by the method of 16S rDNA gene sequencing, so it was named Streptomyces griseorubiginosus N-5. The strain N-5 obtained in this study possessed the characteristics of high tolerance to high concentrations of ammonia nitrogen and strong degradation capability. It holds great application prospects for treating livestock wastewater.

Key words: ammonia degradation, screening, degradation rate, Streptomyces griseorubiginosus