Disinfection of hospital-derived antibiotic-resistant bacteria at source using peracetic acid

Abstract

This work evaluated the removal of hospital-derived antibiotic-resistant bacteria (ARB) from source, using peracetic acid (PAA). Four pilot experiments, two using raw hospital wastewater and two using municipal wastewater, were conducted using three PAA concentrations at different contact times. These contact times were selected in order to mimic the retention time of wastewater in a pipe running from a hospital to a wastewater treatment plant (WWTP) with high and low flows. In order to confirm the PAA dose delivered in the pilot experiments, comparable PAA treatments were made in parallel in batch experiments on the untreated wastewater. PAA degradation was swift in the pilot and batch experiments, and no adverse effects were envisioned for the WWTP from the residual PAA. The numbers of multi-resistant and ciprofloxacin-resistant bacteria were higher in the hospital wastewater compared to the municipal WW, as the hospital was the point source of ARB. The estimated cost of 0.06 € is needed to remove 99.9% ciprofloxacin-resistant bacteria using 50 mg/L PAA and 20 min contact time. Similarity on the removal of ciprofloxacin-resistant bacteria from the pilot experiment and batch experiments performed in the laboratory was observed, and it increased based on increasing contact time and PAA concentration. The method appears to be an ideal technology to minimise the risk ARB poses to sewage workers when new centralised super hospitals are being constructed in Denmark and utilise an unbranched direct wastewater pipe from the hospital to the WWTP.