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Different groups of emerging pollutants (EPs) were identified (drugs, pesticides, hormones, illicit drugs, and fire retardant), and the removal of four antibiotics was determined (sulfamethoxazole 62.2–94.4%, ciprofloxacin 71–83.1%, norfloxacin 82–89%, and ofloxacin 78–97.9%) in a municipal wastewater treatment plant (WWTP) in Acapulco, Gro. Mexico. The compounds were extracted from influent and effluent samples by solid phase extraction (SPE). The identification of non-target EPs was performed by liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS). The antibiotic quantification was performed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Most of the non-target compounds were detected only in the influent samples. Antibiotics levofloxacin and nalidixic acid, the anticonvulsants carbamazepine and oxycarbamazepine, the local anesthetic lidocaine, and the pesticide tridemorph were the main EPs not removed by the WWTP. In this study, it was shown that the Aguas Blancas WWTP does not manage to remove 100% of the various EPs identified in the effluent, although the elimination degree is high in most cases, despite being one of the model plants in Mexico.

A specific analytical method for soaps in the environment has been developed. Three main steps are involved in the process: (i) removal of fatty materials (lipids) other than soaps; (ii} derivatization of soaps with either bromomethyl-methoxy-coumarin or p-bromo phenacyl bromide to get a suitable response by ultraviolet; and (iii) separation of different carbon-chain fatty soaps by highperformance liquid chromatography, followed by either ultraviolet or fluorometry detection. The method has been applied successfully to anaerobically digested sludges produced in several waste water treatment plants. Substantial amounts of soaps have been found in sludges entering and leaving the anaerobic digestor. After conducting a mass balance, 70% soap biodegradation was found in the above digestor.

This paper presents the analysis of the variation of haloacetic acids (HAAs) for different pipe materials in a distribution system. The work involved an experimental study on a simulated distribution system assembled in the Hydraulic Laboratory of the Engineering Institute at the National Autonomous University of Mexico (Instituto de Ingeniería UNAM). Two different scenarios were investigated based on different pipe materials, variation of temperature and initial chlorine concentrations (4.0 and 4.5 mg/L). Feed water with varying amounts of organic content was dosed with varying amounts of chlorine concentration. Water samples were collected from different locations in the distribution system and analyzed for physicochemical properties and HAAs determination. The results of this research demonstrated that the concentration of HAAs in the different segments of the distribution systems varied depending on pipe material, initial chlorine concentration, pH, residence time and the presence of natural organic matter.

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The main objective of this study was to determine the occurrence of polycyclic aromatic hydrocarbons (PAHs) in surface water samples collected from different points along the stream that flows through the Campus of the Federal University of Santa Maria, RS-Brazil. Before reaching the campus, the water in the stream is already contaminated by wastewater discharged from the surrounding, and once inside the Campus, additional wastewater from a Gas Station situated close to the University hospital. A bench scale photodegradation experiment was conducted of the occurring traces of anthracene, phenanthrene and naphthalene, with the aid of a stirred tank reactor and polymer-supported TiO as a catalyst. To prevent loss of the low soluble analytes, it was necessary to add 5% and 10% acetonitrile, as an organic modifier of the synthetic aqueous solutions and real samples, respectively. An experimental design was employed and the best conditions for the photocatalysis of the aqueous solutions and real samples were pH 9 and pH 7, and 35°C and 30°C, respectively. Under optimized conditions, the analytes were completely degraded after 60 min of irradiation. The subproducts of the photocatalysis were identified through gas chromatography/mass spectrometry, and fragmentation routes were proposed. The mean concentrations of PAHs in the polluted surface water and hospital wastewater were relatively high: 3.9 ± 1.7 and 21.5 ± 2.8 µg L, respectively. A preliminary risk assessment revealed that the presence of anthracene requires particular attention. The risk posed by the occurrence of PAHs in the surface water and hospital wastewater samples confirms the need for an efficient treatment system.

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