On‐site pilot‐scale advanced oxidation pretreatment of hospital wastewater: assessment of pharmaceuticals, pathogens, antibiotic resistance genes and acute ecotoxicity

BACKGROUND Hospital premises generate wastewater containing a wide spectrum of contaminants, such as pharmaceutically active compounds ( PhACs ), antibiotic resistance genes ( ARGs ) and pathogenic microorganisms, whilst plenty of them are classified under the antibiotic resistant bacteria ( ΑRΒ ) category. These contaminants are of great concern, as they could have serious repercussions to the environment and public health. In the current study, a pilot‐scale unit based on Advanced Oxidation Processes ( AOPs ), was installed and operated on hospital's premises, in order to treat a highly contaminated stream of real hospital wastewater (HWW), evaluating: UV/H 2 O 2 , UV/TiO 2 ‐A, UV/TiO 2 ‐B, UV/H 2 O 2 + TiO 2 ‐A and UV/H 2 O 2 + TiO 2 ‐B at contact times of 6 and 11 h. RESULTS According to the results, 93 pharmaceuticals, parent compounds and metabolites, were detected and quantified using LC‐QTOF‐MS in the HWW produced in a building housing specific medical services. Their concentrations ranged between a few μg L −1 and several hundreds μg L −1 , while the concentrations of pathogens ranged from 10 3 to 10 6 CFUs 100 mL −1 . The removal rates of the sum of pharmaceuticals after 6 h of treatment were 44.6% and 40.4% for UV/H 2 O 2 and UV/TiO 2, respectively. Acute toxicity to Daphnia magna decreased after treatment; at 25% (v/v) HWW, the UV/H 2 O 2 effluent after 6 h caused 0% immobilization. In contrast, TiO₂‐based treatments remained toxic at 6 h, but toxicity was decreased after 11 h, with immobilization to 40–60% at 50% (v/v) HWW. Regarding the examined bacteria Enterococci, Escherichia coli, Klebsiella sp., and Staphylococcus sp. , both treatment processes achieved almost complete elimination. In contrast, although a decrease in the concentrations of ARGs was observed, they exhibited complex behaviour and remained in remarkable concentrations in the effluents. CONCLUSION: The results demonstrated that the applied processes have the potential to be implemented in the future for on‐site pre‐treatment of heavily contaminated HWW.