Leaching of Heavy Metals in Soils Conditioned with Biosolids from Sewage Sludge

Abstract

A promising use of biosolids is as organic fertilizer in agricultural and forestry activities. However, its composition might contain several pollutants, especially heavy metals, which may result in an increase in the concentrations of these elements in the soil and the risk of groundwater contamination. This study aimed to determine the leaching levels of ions in a Ferralsol (clayey texture) and in a Planosol (sandy texture). The experiment was conducted in a greenhouse at Embrapa Agrobiologia, Seropédica, Rio de Janeiro state. Soils were packed in PVC columns and received 2 L/column of biosolids. The concentrations of heavy metals present in the biosolids composition were below the limits established by the legislation (CONAMA 375). In addition, the performed simulations showed the absence of contamination risk of soil or groundwater and surface water, according to the limits allowed by CONAMA 375. However, it should be emphasized the potential of nitrate leaching.

Metal contamination of agricultural soils amended with biosolids (sewage sludge) at a ceramic production area in NE Spain: A 10‐year resampling period

“…However, the Cr remained on the surface. Campos et al (2019) found a similar behaviour for Ni and Cr. Tóth et al (2016) carried out a detailed analysis of the heavy content in agricultural topsoils of the European Union (EU).…”

Co-application of a biosolids product and biochar to two coarse-textured pasture soils influenced microbial N cycling genes and potential for N leaching

“…Biosolids are known to be a source of nutrients and micronutrients, as well as a contributor of organic matter for improved soil structure, quality and biological activity 3 , 13 , 44 , 45 . However, there is also the possibility of N leaching and contamination 12 , 21 , especially when they are applied to coarse-textured soils 46 . While co-application of biosolids and biochar can mitigate nitrate leaching 17 associated with physical and chemical properties of the biochar, changes to N cycling pathways in the soil could also contribute to loss of N. Therefore, our investigation focused on microbial processes associated with co-application of LaBC and biochar in soils of different texture in relation to N-use efficiency.…”

Biosolids as planting fertilization of tree species of the Atlantic forest and concentration of nutrients in soil layers

“…Data also indicate that there was no leaching of these elements in the 75 to 100 cm layer and that the values found in all layers are very low, corresponding to less than 10 % of the maximum limits of CONAMA Resolution 498/2020 (Brasil 2020). Campos et al (2019) studied the leaching from the application of 8 liters of sewage sludge biosolids in the layer of 0-25 cm of soil in columns of 20 cm in diameter, filled with clayey Latosols or sandy Planossols. They found in the samples of all collections, that in the leaching from both soils, the levels of nitrates, phosphates and heavy metals were below the limit stipulated by the CONAMA Resolution 498/2020 (Brasil 2020), showing that there is practically no possibility of soil layer contamination by the application of this dose of biosolids, even in sandy soils.…”

“…For forest restoration, there are some planting fertilization works with sewage sludge biosolids from tree species occurring in the Atlantic forest (Paiva et al 2009, Silva and Pinto 2010, Lopes and Leles 2020, Silva et al 2020) and the responses have been quite different, depending on the edaphic and climatic conditions where the stands are located and the differences in behavior of native tree species. Another characteristic of the biosolid is when applied to the soil, its substances have a high power of adsorption to the soil and thus, according to Campos et al (2019), there is no leaching to deeper layers of soil, there is no risk of contamination of the water table. Further field studies on this topic are indicated, due to the large differences in soil and climatic conditions existing in Brazil.…”