Biosolids as soil-amendment: evaluation of nutrient leaching in loamy-silty soil

Municipal sewage sludge is a by-product of wastewater treatment. The amount of sewage sludge has increased with the construction and expansion of wastewater treatment plants, while stricter policies have limited its disposal. Anaerobic digestion is a worldwide technology used in sewage sludge stabilization and pre-treatment step is used to improve its biodegradability. Once sewage sludge is stabilized they are named biosolids. Biosolids composition makes them attractive as a soil amendment. But also, biosolids could be a source of contamination. Therefore, the objective of this study was to evaluate the nutrient leaching in loamy-silty soil of biosolid stabilized with advanced anaerobic digestion. Previous results showed that these biosolids could be applied as a soil amendment considering metal content and phytotoxicity assay. Thus, two biosolids from conventional and advanced anaerobic digestion was evaluated in a soil leaching columns using loamy-silty soil to evaluated phosphorus and nitrogen flux. The columns are 25 cm high and 7.2 cm of diameter. Every 48 h a rain simulation flux of 15 mL of distillated water was added. Then the leaches were collected and analyzed. Preliminary analysis of the results shows a decrease in chemical oxygen demand and apparent stationary state in the first 11 weeks.