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The treatment of landfill leachate requires processes that efficiently remove the different contaminants present in this type of liquid waste. To treat this type of waste, a great diversity of biological processes has been used, which take advantage of the capacity to transform the different components of the liquid medium into biomass; however, these processes have limitations due to the intrinsic characteristics of the leachate. In recent years, the integration of biological processes with Advanced Oxidation Processes has been promoted, which would significantly reduce the toxic characteristics of these wastes to comply with the legal conditions to be discharged into the environment without causing damage. In this work, the authors present a review (2015 to 2021) concerning the biological treatment, and Advanced Oxidation Processes (based on ozone, electrochemical processes, and photocatalysis). These processes are analyzed in combination to describe the optimal conditions under which pollutant loads of landfill leachate are reduced. Finally, it is possible to identify that the treatment processes under study are technologies that can be coupled, registering higher efficiencies and lower generation of waste by-products or sludge. [ABSTRACT FROM AUTHOR]

Titanium Dioxide (TiO2) has been an object of different investigations in the recent years, principally to its applications in solar cells due to its interesting optic, electric and magnetic properties. In this work is presented the dielectric response study of activated carbon doped TiO2 in pressed pills in different Molar relations. The electric behavior of the composites is obtained by bringing the samples to a Nitrogen and Helium atmosphere and studying with complex impedance spectroscopy, in the 50Hz to 5 MHz frequency interval and from room temperature to 723 K. The experimental results showed that the Nitrogen atmosphere leads to an anionic doping, in which an nitrogen anion (A) gets into the TiO2 lattice, replacing an oxygen and forming TiO2-x Ax. [ABSTRACT FROM AUTHOR]

Microbiology cell-staining wastewater was treated by UV/TiO2 thin films photocatalysis. A simple method of applying gravity sedimentation over glass--type substrate was used for the preparation of the films. The use of Na4P2O7, microwaves, and ultrasounds were studied for decreasing the TiO2 grain sizes on the films. It was established that the best method for reducing grain size resulted from a combination of Na4P2O7 (0.01M) and microwave radiation (700 W, 20 min). The Films were characterized by several microscopic and spectroscopic methods. Anatase phase (gap energy of 3.2 eV) and grain sizes averaging 83 nm were achieved. Photocatalysis tests using TiO2--films showed 99.5 % of decolorization, 79 % TOC abatement, and total microbial inactivation after 14 h of treatment. No bacteria re-growth was found 48 h after the treatment was completed. [ABSTRACT FROM AUTHOR]

A predictive molecular adsorption model for organic compounds over TiO2-P25 particles was formulated. The model is an extension of a theoretical method of surface characterization called Protonic Distribution Affinity (PDA), which is obtained from potentiometric titration analysis, zero point charge (ZPC) of the material and adsorption isotherms of the Langmuir-Hinshelwood type. The chemical nature of the compound in the model was established by initial pH and molecular weigh. We found that, for the TiO2,-P25, the ZPC was 6.8. The model was validated using experimental data of dichloroacetic acid (DCA), 4-chlorophenol (4-CP) andphenol (PH) to different conditions. The model has high predictive capacity, numerical stability and sturdiness for obtaining the solutions. For available experimental data, the correlation coefficient was 0.97. [ABSTRACT FROM AUTHOR]