Use of Denitrifying Sludge for the Removal of Acetaminophen in Water

Acetaminophen, more commonly known as paracetamol (APAP), is one of the most widely used analgesics and antipyretic drugs worldwide. Its presence in the environment poses a risk to the organisms it comes into contact with, which is why it has been classified as an emerging contaminant. Given its adverse effects and continuous discharge into water bodies, it is necessary to study efficient, environmentally sustainable processes for its complete removal. Denitrification is a biological process that has been studied for the biodegradation of recalcitrant compounds and certain pharmaceuticals such as 17β-estradiol and ampicillin, transforming them into harmless products such as N2 and HCO3−. In the present study, the biodegradation of 6 mg L−1 of APAP-C was evaluated through a denitrifying process. Batch experiments were conducted, achieving acetaminophen (APAP) removal efficiencies (EAPAP-C) of 83.3 ± 0.86% and nitrate removal efficiencies (EN-NO3−) of 100%. The substrates were predominantly converted into HCO3− and N2, with yields greater than 0.9, while intermediates such as NO2− were observed only transiently during the reaction. At the end of the experimental period, no secondary metabolites were detected, indicating that intermediates did not accumulate to quantifiable levels.