Simultaneous ammonia and Cr (VI) removal by Pseudomonas aeruginosa LX in wastewater

Abstract Inorganic nitrogen and Cr (VI) often co-exist in wastewater and have been a major threat to ecological equilibrium and public health. In this work, we successfully isolated Pseudomonas aeruginosa LX from activated sludge, which was capable of simultaneously degrading ammonia and reducing Cr (VI). Single factor experiments showed that strain LX exhibited efficient ability to remove inorganic nitrogen and it possessed efficient nitrogen removal ability in presence of multiple nitrogen sources. A possible pathway of ammonia removal for strain LX was proposed and was as follows: NH4+-N → NH2OH → NO2--N → NO3--N → NO2--N → NO → N2O → N2. Moreover, more than 80% of 100 mg L-1 NH4+-N could be removed at 30 mg L-1 Cr (VI) and properly increasing ammonia concentration could promote the reduction of Cr (VI). Additionally, immobilized strain LX could degrade ammonia and reduce Cr (VI) to Cr (Ⅲ) well in sequencing batch reactor (SBR). Therefore, strain LX was a suitable candidate to simultaneously remove Cr (VI) and ammonia nitrogen.