The primary source of the discharge of phenols into the environment is industrial activity, such as the production of pharmaceuticals, plastics, and pesticides, being the majority discharged into surface water sources, reaching concentrations around 0.001 to 0.400 mg/L. These compounds are considered a priority contaminant due to their toxicity to aquatic life and effects on human health. The presence of phenols even at low concentrations generates flavour and odour in drinking water. Due to the molecular stability and solubility of phenols in water, their removal by conventional water treatment methods is inefficient. However, adsorption with granular activated carbon (GAC), after conventional filtration with sand and anthracite, is an efficient technique for the reduction of organic compounds such as phenols. This paper studied the effect of applying double filtration to the reduction of phenols present in the filtered water of a conventional drinking water treatment plant, using two types of GAC (vegetable and mineral) and three GAC:Sand configurations (100:00; 00:100; 50:50). The configurations with GAC showed an efficient reduction of turbidity, organic matter indicator variables (UV254 absorbance and total organic carbon) and phenols, the mineral GAC being the most efficient GAC.

La Atrazina es uno de los herbicidas de mayor aplicación en el mundo, ingresa a los cuerpos de agua superficial por escorrentía, aplicación directa o dispersión aérea. Los métodos de tratamiento convencional de agua no remueven eficientemente este tipo de contaminantes, mientras que la adsorción con Carbón Activado Granular (CAG), es una técnica apropiada para la remoción de compuestos orgánicos del agua. En este trabajo, se evaluó la reducción de Atrazina de un agua dopada con dos concentraciones Atrazina, durante el proceso de tratamiento convencional (coagulación, floculación, sedimentación y filtración con arena y antracita) seguido de una doble filtración con dos medios adsorbentes granulares (CAG de origen Vegetal y Mineral), la cual permitió obtener una eficiente reducción de UV254 (86%) y Atrazina (99%).

The type of hazards and hazardous events in watersheds, depend on land uses around them. Atrazine is an organic pollutant widely applied as a pesticide and it is a potential chemical hazard present in water sources, which cause water pollution and negative effects on aquatic life and human health, due to its high solubility and persistence in soil. However, for developing countries, monitoring and quantification of atrazine can be complex and costly; thus, to contribute to establishing strategies for risk assessment in water supply watersheds, it was evaluated the potential use of an easy, rapid and low-cost technique such as ultraviolet (UV) absorbance to identify the presence of atrazine. It was conformed distilled and surface water samples doped with Atrazine, and there were correlated with the UV typical spectrum indicator of organic material presence (wavelength λ: 200 - 300 nm). The optimal λ range was 203 - 223 nm to identify this substance at levels possible to be found in surface sources, being UV223 more adequate than UV254, which is more used to identify the presence of natural organic matter, which shows that UV223 is a complementary tool to chemical risk assessment for atrazine in drinking water supply systems.