Physicochemical Properties of Artificial Soil Composed of Sewage Sludge, Fly Ash, and Slag

Abstract

The pH, electric conductivity (EC), nutrients, heavy metals, water-holding capacity and water permeability of stabilized sewage sludge were investigated by mixing municipal sewage sludge with alkaline fly ash and slag. The results indicate that the evaporation of soil moisture increases and water-holding capacity decreases in these artificial soils with an increase of slag, and the infiltration rate of artificial soils increases to improve its water permeability by adding slag to sewage sludge. The pHs of stabilized artificial soils range from 7.5 to 8.0 for a weak alkaline soil, which tend to be neutral by adding slag to sewage sludge. The ECs of stabilized artificial soils range from 2.93 to 3.71 mS•cm-1, indicating the higher salt content in these artificial soils. The nutrient contents of stabilized sewage sludge are up to a high fertilizer level and available nutrients increase with the increase of the ratio of slag to sewage sludge in these artificial soils. Cd, Ni, Pb, Cu and Zn for all artificial soil treatments are lower than control standards for pollutants in sludge and fly ash for Agricultural use.