Pollution has been increasingly affecting soil, air, and water. Nitrogen compounds and antibiotics belonging to the group of emerging organic compounds (EOCs) have been detected as one of the contaminants most frequently present in water. The denitrifying process is an alternative to remove simultaneously nitrogenous (NO3-) and carbonaceous matter. The objective of this work was to evaluate in batch assays the ability of a stabilized denitrifying sludge without prior exposure to antibiotics to eliminate and mineralize tetracycline (TET) and ciprofloxacin (CIP) as the only source of electrons. Consumption efficiencies (E, %), products yield (Y, mg C or N produced/mg C or N consumed), and specific consumption (qTET, qCIP, and qNO3) and production (qHCO3, qN2) rates (q, mg C or N/ g SSV h) were used as response variables for evaluating denitrification with 20 mg antibiotic-C/l. Within 24 h of culture, total elimination of CIP (E = 100%) and partial elimination of TET (E = 69%) were achieved. Antibiotic losses due to adsorption and chemical reaction were not significant. Both antibiotics were completely mineralized to HCO3- whereas NO3- was completely reduced to N2 (YHCO3 and YN2 close to 1). The denitrifying process using TET was slower than that using CIP, as qTET, qHCO3, and qN2 values were 57-73% lower than those obtained in the assays with CIP. Denitrifying sludge showed the ability for using both antibiotics as the only source of electrons to perform the denitrifying process without the accumulation of carbonated or nitrogenous intermediates.

https://zoom.us/j/99261302467?pwd=TTBVbTUxaUdHSzNuQlFuOVF2NDVZUT09