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Electrocoagulation intensified by uv radiation to remove cod, cot and tds in wastewater of the textile industry using graphite electrodes
Contextualization: The textile industry makes use of large quantities of water and various chemicals that are part of the different stages of the cloth processing, including painting and finishing. As a result of the use of these chemicals, wastewater from the textile industry has high concentrations of chemical oxygen demand (COD), total organic carbon (TOC), total dissolved solids (TDS) and low biodegradability.
Knowledge gap: Currently, the different industries in Colombia have failures in the final disposal of wastewater, since it has been identified that some industries do not comply the regulations that establish the maximum permissible values of some pollutants in their discharges. Specifically, the textile industry consumes large volumes of water and contributes considerably to the pollutant loads in the water bodies, which is why searching for alternatives to improve the treatment of this type of effluent is a matter of particular interest. On the other hand, current techniques for the treatment of these waters require the use of different chemical inputs, so the evaluation of electrocoagulation with graphite electrodes and UV radiation represents an alternative that allows reducing the consumption of inputs and reducing the concentration of pollutants present in these effluents.
Purpose: This research aims to evaluate the electrocoagulation process in water treatment, using graphite electrodes and intensified by UV radiation, to determine the percentage of removal of COD, TOC, and TDS in the wastewater of the textile industry.
Methodology: Experimental research was carried out to evaluate the technique of electrocoagulation, intensified by radiation from a submersible UV lamp. For methodological development, some physical and chemical parameters were measured before and after each test. A factorial-type experimental design was carried out, with two factors in three levels 32), specifically 9 trials; all of which were performed in triplicate for a total of 27 experiments. The factors or variables selected were the initial pH of the wastewater (6, 7 and 8) and the electric current intensity applied (0.5 A, 1 A, and 1.5 A). The response variables selected were the percentage of removal of COD, TOC, and TDS. After all the trials, the results were evaluated by analysis of variance to determine the effect or influence of each factor on each of the response variables.
Results and conclusions: The tests determined that the most favorable experimental conditions for the electrocoagulation process were pH 8 at a electric current intensity of 0.5 amperes. The process has high efficiency in the percentage of removal of COD, TOC, and TDS for each of the tests, which is consistent with the use of inert electrodes that have greater chemical resistance than other electrodes, which facilitates the oxidation and reduction process in conjunction. Besides, the use of UV radiation intensifies the process by giving rise to the formation of ozone and OH* radicals in water, specially having an alkaline pH. These factors combined allow that higher values can be achieved in the removal of various contaminants present in the wastewater of the textile industry.