Chromatographic procedures such as solid phase extraction and high performance liquid chromatography coupled with a fluorescence
detector (SPE-HPLC-FLD), were carried out to determine the concentrations of the surfactant nonylphenol ethoxylate (9 ethylene
oxide units,NP9EO) and its biodegradation product, 4-nonylphenol (NP), in samples collected from the wastewater treatment system
at the University Hospital (HUSM) of the Federal University of Santa Maria. The results showed a high concentration of NP9EO
in all the collected samples (0.075 – 4.12 mg L−1) and an almost complete absence of NP. In addition, electrocoagulation (EC) of
NP9EO was carried out in aqueous solution and in the HUSM effluent. A NP9EO removal rate of 95 % was achieved from the
aqueous solution, following a pseudo-first-order kinetics. Through LC-MS measurements in aqueous solutions, it was possible to
determine the formation of short-chain nonylphenol ethoxylate (NPEO), such as nonyl-phenoxy acetic acid (NP1EC), after 30 min
of EC. In the case of the HUSM wastewater, the NP9EO removal was 89 %, and the chemical oxygen demand (COD) abatement was
26 %. A respirometric test was conducted to measure the increase of biodegradability during the EC and the aqueous samples were
found to be less readily biodegradable before the 30-min period of electrocoagulation than after it had been completed.
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