Caracterización del contenido en nutrientes y metales pesados en lodos provenientes de la Planta de Tratamiento de Aguas Residuales de Ambato (PTAR)

Abstract

Sustainable soil management is a priority for food production and environmental protection; therefore, sewage sludge becomes an agricultural management strategy to improve soil properties. This is the reason why, the centrifuge sludge and solidified sludge from the PTAR-Ambato were characterized based on their physicochemical characteristics (moisture content, organic matter and pH), heavy metal content (Cr, Pb, Cd, As, Co, Ni, Al) and nutrients (N, P, K, Ca, Mg, S, Fe, Cu, Zn, Mn). Through the maximum and minimum limits analysis, established in the current environmental regulations, the use of residual sludge in agriculture was measured. Indeed, the high content of nutrients (percentage) N, P and K with 3.05, 2.15 and 0.77 in centrifuge sludge; and 0.92, 41.27 and 1.01, in solidified sludge, respectively, make it a potential resource for nutrient recycling. However, the high moisture content (percentage) with 389.61 and 70.56, the low organic matter content (percentage) with 10.97 and 0.68 in centrifuge sludge and solidified sludge, respectively, as well as the high content of heavy metals (milligram per kilogram) such as elemental aluminum with 759.43 and hexavalent chromium with 82.68 limit their use in agriculture. In conclusion, residual sludge from the PTAR-Ambato could be stabilized before final disposal by prolonged alkalinization, composting or vermicomposting to obtain a product suitable for agriculture.