Agricultural Valorization of Urban Sewage Sludge: Short-Term Effects on Trace Elements Contamination in Cultivated Soil

Abstract

Urban sewage sludge (USS) contains potentially hazardous Trace Elements (TEs), including Zn, Cu, Cr, Ni, Pb, and Cd, as well as Trace Organic Contaminants such as Hydrocarbons and Aromatic Polycyclic Hydrocarbons (PAHs). The accumulation of TEs in agricultural soils increases their uptake by crops, which affects food quality and human health. The objective of this study is to evaluate the short-term effects of application rates on total TE (TTE) and soil metallic pollution in cultivated soil in Boukhalfa, Tizi-Ouzou, Algeria, to prevent soil contamination and associated ecological and health risks. Based on legislative recommendations for its use in agriculture, TTEs and PAHs in the USS and TTEs in soil samples were analyzed. To evaluate their impact on soil pollution, a completely randomized block design was implemented. A year later, three samples of soil from each of the elementary plots (EP) were collected from the top layer (0-20cm) to form composite samples. The results for TTE contents in the soil and PAH concentrations in USS demonstrate that the studied soil is suitable for the application of the studied USS. Analysis of TTEs and pollution index determined in control and amended soils showed values increases corresponding to application rates; however, all values remained below regulatory limits. Short-term application at rates of 15, 30, and 45t.ha^-¹ did not result in soil contamination by multiple TEs.