Nonylphenol polyethoxylate in hospital wastewater: a study of the subproducts of electrocoagulation.

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.

Ciprofloxacin in hospital effluent: degradation by ozone and photoprocesses.

There are several papers in the literature that have recorded satisfactory results for the degradation of different pharmaceuticals in aqueous solutions by means of oxidation processes; however, only a few of them relied on real samples in carrying out their investigations. This study examines the results of the performance of photo-induced oxidation, heterogeneous photocatalysis, ozonation and peroxone in degrading the fluoroquinolone antimicrobial ciprofloxacin (CIP) in a hospital effluent. The real samples were collected from the treatment system of the University Hospital of Santa Maria (HUSM). Liquid chromatography with fluorescence detection (LC-FLD) was used to monitor the decrease of the CIP concentration. As expected, photo-induced oxidation was much slower than the other processes in bringing about total CIP degradation. Both heterogeneous photocatalysis and peroxone led to almost complete CIP degradation after 60 min treatment. Ozonation showed the best performance: total degradation after 30 min treatment. This was an unexpected result in view of the greater capacity of the other two processes to generate hydroxyl radicals. However, this finding supports a result in the literature that has tended to be overlooked. The by-products formed during the application of the processes were found to be very similar. Moreover, on the basis of the data obtained from the literature, there is some evidence to suggest that the by-products are derived from the oxidation of the piperazine group.

Photo-degradation of the antimicrobial ciprofloxacin at high pH: identification and biodegradability assessment of the primary by-products.

Photo-treatment for the removal of pharmaceuticals in effluents is a topic currently under discussion. In some countries effluents from hospitals are directly emitted into open ditches without any further treatment and with very little dilution. Under such circumstances photo-degradation in the environment can occur. However, photo-degradation does not necessarily end up with the complete mineralization of a chemical. Therefore, photo-product biodegradability and toxicity against environmental bacteria is of interest. Hospital effluents have often a pH around 9. Therefore, photo-oxidation (150W medium-pressure Hg-lamp, batch reactor) of ciprofloxacin (CIP) was studied at pH 9. The primary elimination of CIP was monitored and structures of photo-products were assessed by liquid chromatography ion trap mass spectrometry (LC-MS/MS). Five compounds were identified as probable products of photo-defluorination, -decarboxylation and loss of the piperazine moiety. These photo-products were not biodegradable in the Closed Bottle test - OECD 301D. They did not affect Vibrio fisheri in the applied concentrations.

Influence of variables of the combined coagulation-Fenton-sedimentation process in the treatment of trifluraline effluent.

The effluent stream from the industrial production of the herbicide trifluraline (amination water) was submitted to a combined treatment of a physical-chemical process (coagulation) with an advanced oxidation process (Fenton). The recovering of the residual sludge was performed. The combined coagulation-Fenton-sedimentation process proved to be very suitable for wastewater color reduction (91.6%), promoting considerable abatement of the organic load (63.4% COD reduction). According to the fractionary factorial design, the main effects of pH (A) and Fenton sludge (B) variables were considered statistical fluctuations of the process (and not decisive), while the main effects of Fe(3+) (C), Fe(2+) (D) and H(2)O(2) (E), as well as the interactions between variables A and B, A and E, C and D and C and E were considered significant. The obtained results suggest that the combined process can be advantageous for the treatment of recalcitrant industrial effluents, such as the amination water from the trifluraline production.