VIII Congreso Internacional de Investigación REDU
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Publicado el 25 de abril de 2022 | http://doi.org/10.5867/Medwave.2022.S1.CI42
Electrocoagulación como tratamiento alternativo de agua potable para la remoción de calcio y manganeso en el municipio de San Cristóbal, Paute-Ecuador
Electrocoagulation as an alternative drinking water treatment for calcium and manganese removal in the municipality of San Cristóbal, Paute-Ecuador
Jonathan Israel Méndez Ruiz , María Beatriz Barcia Carreño, Cristian Alfonso Salas Vazquez, Priscila Estefania Valverde Armas
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Tema
Ciencias de los recursos naturales
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Palabras clave
Contaminants, greener process, groundwater, hard water, sludge
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Introducción
Only 37.2% of the rural population of the municipality of San Cristobal in the canton of Paute-Azuay received drinking water according to INEN in 2010. It has 2794 inhabitants, and this is expected to grow to 3406 by 2041. Water analysis results published by the local authorities of Paute reported a high concentration of hardness, e.g. 442±32 mg/L of CaCO3 and manganese 0.97 mg/L in the groundwater catchment source. These results far exceed the concentrations required by the World Health Organization (WHO) for drinking water as hardness and Mn can affect the water distribution systems and the people health. The WHO recommends the concentration of Ca2+ to be 200 mg/L and the level of Mn to be <0.4 mg/L.
Objetivos
To test the electrocoagulation process as an alternative water treatment to evaluate the removal of Ca2+ and Mn in water to design the reactor, considering technical, environmental, and socioeconomic criteria.
Método
The electrocoagulation process was performed under galvanostatic conditions in a single compartment electrochemical cell using a two-electrode setting (carbon steel) and filled with 150 mL of water coming from the sedimentation stage of the treatment plant. The experiments were performed under different current densities, pH, operating and sedimentation times using batch process. Ca2+ concentration rate was measured by EDTA titrimetric method. To enhance the removal of contaminants Ca(OH)2 was added. Unstable parameters rate such as total dissolved solids, electrical conductivity, and pH were measured to assess their influence in the process. In addition, chemical oxygen demand (COD) was measured to evaluate if additional chemicals are generated during the process. To estimate the amount of sludge generated, sedimentable solids were measured in the Imhoff cone. These results are inputs in reactor design.
Principales Resultados
Experimental results showed that higher efficiencies are achieved in basic water (pH~8), using an applied current density of 9.56 mA/cm2 and operating time of 60 min. Under these conditions, the efficiency of Ca2+ removal was 59.3%. It was observed that the sedimentation process did not strongly influence the efficiency of the process.
The addition of 100 μL of Ca(OH)2 at 20% increases the removal efficiency to 85% for Ca2+ and 97% for Mn. The electrical energy demand was 1.13 kWh/m3 and the dosage of Ca(OH)2 was 0.13 Kg/m3. No alteration in the COD concentration was registered and the generation of sludge was 2.2 times lower than the amount generated using a conventional flocculation process.
The diameter of the electrocoagulation reactor is 9 times of the electrode diameter, while the height of the reactor is 2 times the height of the electrode. The electrode separation distance must not be longer than 0.35 times the diameter of the reactor.
Conclusiones
Electrocoagulation is a more sustainable process since it produces the coagulant in-situ with low production of sludge mostly biodegradable. In this study the removal of Ca2+ and Mn was optimized obtaining efficiencies >85% where the addition of Ca(OH)2 enhances the electrocoagulation process. The low energy consumption in the electrocoagulation reduces the operational costs of this treatment alternative.
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