Relevance of Organic Matter Fractions as Predictors of Wastewater Sludge Mineralization in Soil

Virginie Parnaudeau (1) , Bernard Nicolardot (1) , Jérome Pagès (2)

1 UA LRM - Unité de Recherche Agronomie Laon-Reims-Mons
2 Ecole Nationale Supérieure Agronomique de Rennes

Seventeen different wastewater sludges were characterized using both chemical and organic matter fractionation methods (water extraction, Van Soest method, and acid hydrolysis) and 6-mo incubation studies to assess their decomposition in soil. Simple correlation and multiple factor analysis (MFA) were then performed to establish relationships between composition and C and N mineralization of sludges. Carbon and N concentrations covered a wide range of values, but organic carbon (Co) to organic nitrogen (No) ratios were relatively low (from 5 to 19). Carbon and N were mainly distributed in the most soluble fractions of the Van Soest method and in the water-insoluble fraction at 100°C. Carbon mineralization varied from 180 to 661 g C kg−1 organic C added during the 168-d incubation. The addition of sludges led to different inorganic N dynamics: from −3.3 to +120.0 g N kg−1 sludge organic C mineralized after the 168-d incubation. Fractionation studies showed that the most discriminating method was acid hydrolysis. Carbon mineralization was linked with the proportion of sludge N and C present in the lignin-like fraction (r = −0.68 and −0.65, respectively). Significant relationships were established between N mineralization and No to Co ratio (0.88 < r < 0.95) and the Co to No ratio of sludges, the C to N ratio of the soluble fraction obtained by the Van Soest method, the water-soluble fraction at 100°C, and the C and N present in the acid-hydrolyzable fraction. Finally, multiple factor analysis also enabled establishing a sludge typology using five clusters based on composition and mineralization characteristics.

Domaines: Agronomie; Science des sols

Virginie Parnaudeau, Bernard Nicolardot, Jérome Pagès. Relevance of Organic Matter Fractions as Predictors of Wastewater Sludge Mineralization in Soil. Journal of Environmental Quality, 2004, 33 (5), ⟨10.2134/jeq2004.1885⟩. ⟨hal-01862618⟩