Sanitary landfill leachate (SLL) is a mixture of highly toxic and recalcitrant pollutants that threatens the water quality of the Yucatán Peninsula karst aquifer, one of the most extensive aquifers on the planet. To reduce the adverse environmental impacts of this wastewater, a triple-stage Fenton process (FP) was applied in an old SLL. Removal efficiencies were evaluated in terms of physicochemical variables, metal(oid)s concentrations, mass spectrometric identification of organic compounds and Daphnia magna acute toxicity test. The triple-stage FP achieved an 88% chemical oxygen demand (COD) removal, representing an improvement of 13% compared to FP performed in a single stage. Further, metal(oid)s such as aluminum, arsenic, chromium, nickel and zinc as well as organic compounds were substantially reduced. With respect to acute toxicity, the treatment produced a 64% reduction. Thus, this treatment system seems to be an effective option to reduce the dangerous level of SLL.

The objective of this investigation was to identify and quantify the presence of Bisphenol-A (BPA) in raw and treated leachates with the Fenton-adsorption process. BPA is used as a monomer to produce epoxy resins and it is a compound classified as endocrine disruptor. For this reason, it is important to quantify its presence in effluents that will be disposed to the environment to avoid damage to human health and other organisms. The Fenton-adsorption process consisted in the implementation of an advanced oxidation using H2O2 and FeSO4 applied to the raw leachate and subsequently the application of the adsorption process through a column packed with activated carbon. The quantification of BPA was carried out by gas chromatography coupled to mass spectrometry, using liquid-liquid and liquid-solid extraction methods. A recovery percentage study was carried out to validate the extraction methods. Finally, it was found that the leached evaluated contained >12 mg L-1 and at the end of the treatment its concentration was <0.0174 mg L-1.

Although septic tanks is the most common wastewater treatment device used in the State of Yucatan, Mexico, it is a deficient purification process and therefore further treatment is needed. This work presents the results from a pilot-scale rotating biological contactor (RBC) process used to treat septic tank effluent. The RBC was operated with three organic loading rates (5.2, 15.9 and 17.2 g BOD5/m²·d) and two rotation velocities (15 and 30 rpm). COD, BOD5, TKN and NH3-N removal efficiencies were measured and a factorial analysis was carried out to determine the best operating conditions. The organic loading rate was shown to be the variable that had the greatest effect on the process, with lower loads and better efficiency (roughly 90% for COD and BOD5). Rotation velocity was significant for the removal nitrogenous matter. The most efficient combination was found to be 5.2 g DBO5/m²·d at 30 rpm, which is equivalent to a tangential velocity of 16.49 m/min.

La fosa séptica es el dispositivo de tratamiento de aguas residuales más utilizado en el estado de Yucatán, México; sin embargo, es un proceso deficiente de depuración y por tanto es necesario proporcionarle un tratamiento posterior. Se presentan los resultados de un proceso tipo contactor biológico rotatorio (CBR) a escala piloto para el tratamiento de efluentes de fosas sépticas. El reactor CBR fue operado con tres cargas orgánicas (5.2, 15.9 y 17.2 g DBO5/m²·d) y dos velocidades de rotación (15 y 30 rpm). Se midieron las eficiencias de remoción de DQO, DBO5, NKT y N-NH3, y se determinó mediante un análisis factorial cuáles eran las mejores condiciones de operación. Se demostró que la variable que más afecta al proceso es la carga orgánica aplicada; a menor carga, mayor eficiencia (casi 90% para DQO y DBO5). La velocidad de rotación resultó significativa para la remoción de materia nitrogenada. La combinación más eficiente para la remoción de materia orgánica fue con 5.2 g DBO5/m²·d y con una velocidad de rotación de 30 rpm, que equivale a una velocidad tangencial de 16.49 m/min.