RESUMO
Simultaneous nitrification and denitrification (SND) was established under continuous aeration (6â¯mgO2â¯L-1) aiming at achieving a feasible and simple operational strategy for treating multi-electrolyte saline wastewaters. Two Structured Fixed-Bed Reactors (SFBR) were used to assess SND performance with (Saline Reactor, SR) and without (Control Reactor, CR) salinity interference. Salinity was gradually increased (from 1.7 to 9â¯atm) based on the composition of water supplied in arid regions of Brazil. At 1.7â¯atm, N-NH4+ oxidation and Total Nitrogen (TN) removal efficiencies of 95.9⯱â¯2.8 and 65.76⯱â¯7.5%, respectively, were obtained. At osmotic pressure (OP) of 9â¯atm, the system was severely affected by specific salt toxicity and OP. High chemical oxygen demand (COD) removal efficiency was achieved at all operational conditions (97.2⯱â¯1.6 to 78.5⯱â¯4.6%). Salinity did not affect microbial diversity, although it modified microbial structure. Halotolerant genera were identified (Prosthecobacter, Chlamydia, Microbacterium, and Paenibacillus).