Print version ISSN 0120-9965
GIRALDO, Óscar and LOZANO DE YUNDA, Amanda. Effect of drying of biosolids from the wastewater treatment plant El Salitre (Bogotá) on the content of nutrients, heavy metals, and pathogens. Agron. colomb. [online]. 2006, vol.24, n.2, pp. 348-354. ISSN 0120-9965.
Biosolids from the wastewater treatment plant El Salitre (Bogotá) were conditioned for agricultural or forest use. It was expected that the product would fit within the Environmental Protection Agency (EPA) established maximum limits for pollution agents and maintain high level of nutrients. Thermal drying treatments at temperatures of 50, 55, 60, 65, and 70 °C were performed. Total coliform, E. coli and Salmonella content, total nutrients content (N, P, and K), and available heavy metals (Cd, Cr, Cu, Mn, Ni, Pb, and Zn) were determined before and after each treatment. Drying treatments between 55-70 °C reduced total coliform and E. coli contents till proper forest use levels. Although nutrient content was reduced 75-95%, it is still considered as a good fertilizer. The content of available Cu and Zn increased, whereas contents of Cd and Cr were not detected, and contents of some heavy metals (Mn, Ni, and Pb) were reduced. All heavy metals contents were below EPA limits for agricultural use. In conclusion, drying treatments could be considered as a valid option to condition El Salitre wastewater sewage biosolids for their forest use.
Keywords : biofertilizer; thermal treatment; agricultural use; total coliforms; E. coli; Salmonella.