Sewage Sludge Storage on Soils around a Wastewater Treatment Plant. Impact on Some Soil Properties

"N. Poushkarov" Institute of Soil Science, BG - 1080 Sofia, Bulgaria


ATANASSOVA, I., M. TEOHAROV, S. MARINOVA and E. FILCHEVA, 2006. Sewage sludge storage on soils around a wastewater treatment plant. Impact on some soil properties. Bulg. J. Agric. Sci., 12: 51-62

Soil samples (topsoil and subplots) treated with sludge originating from domestic and municipal sewage waters of the Sofia waste water treatment plant were studied in relation with the impacts on some chemical, physical and physico-chemical properties. Different relationships and trends in the analyzed parameters were found. For instance, electrical conductivity increased in the sludged soil, but not in the control variant and was strongly and positively correlated with TOC, humified C, NO3-N and K. Total organic carbon and pH were positively correlated with NH4-N, while humified C to the NO3-N. Available P and K were also positively related with NH4-N, which is an indication of the effect of the sludge.
In the control soil, EC was negatively correlated with TOC and the organic carbon parameters and TOC was negatively correlated with NH4-N. The results from the statistical analysis of the chemical, physical and physico-chemical data of treated and control soils indicate that past storage of sewage sludge on Fluvisols had caused considerable perturbations in the soil. This could lead to unexpected changes in the behavior of inorganic and organic pollutants present in the sludge.

Key words: sewage sludge, soil profile, available macroelements, statistical analysis