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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.