Screening salt tolerant heterotrophic nitrifying bacteria from the collecting groove region in ion-type rare earth mines and its nitrogen removal characteristics

To screen the salt tolerant microorganism with high salinity and ammonia nitrogen mining and metallurgy wastewater, the samples were collected from the collecting groove region of ion-type rare earth mines in south of Jiangxi province, and the salt tolerant heterotrophic nitrifying bacteria were cultured and isolated by selective medium. Apart from that, the effect of carbon source, pH, and salinity on its nitrogen removal performance was investigated. The results show that a salt tolerant heterotrophic nitrifying bacterium X1 is isolated and identified as Enterobacter sp. X1 by 16 S rDNA analysis. The suitable condition for nitrogen removal is determined as follows: the sucrose is the carbon source, the pH value equal to 5, and the salinity less than or equal to 15 %. The removal rate of NH₄⁺-N of strain X1 could reach above 60 %. These results could provide a reference for the microbial treatment of wastewater with high salt and ammonia nitrogen.