The pollution effect on the denitrifying capacity of methanogenic sludges

The denitrification process has been studied for biodegradation of some emerging contaminants (ECs). For this, anaerobic sludges from different Wastewater Treatment Plants (WTP) have been used; however, the biodegradation capacity can differ due to the contact they have had with various pollutants, given their origin. This work aims to evaluate the kinetic and metabolic capacity of two denitrifying sludges from different WTPs to biodegrade CH₃COO^--C and NO₃^--N. Denitrifying tests were carried out in batches with CH₃COO^--C (30 mg L^-1) in a CN^-1 relationship of 1.8 with sludge from a WTP of an educational center (WTP-A) and CH₃COO^--C (50 mg L^-1) to a CN^-1 of 1.4 with another from the WTP of Atotonilco de Tula, Hidalgo, México (WTP-B). The results showed that the biodegradation rate of CH₃COO^--C and NO₃^--N with the WTP-B sludge was 35 and 75% greater, respectively, compared to the WTP-A sludge. Therefore, we suggest that the consumption difference of substrate is attributable to the sludges of WTP, which have been exposed to a high concentration of a great variety of pollutants.