The effect of waste sulfur obtained during biogas desulfurization on the availability of selected trace elements in soil

Abstract

Research concerning the effect of the application of waste sulfur pulp (doses: 10, 20, 30, 60 mg S • kg–1 d.m. of soil) on selected soil properties was carried out. The pulp contained sulfur in the elemental form. Before setting up the experiment, the soil had a slightly acid reaction (determination in 1 mol • dm–3 KCl) and was not contaminated with heavy metals. After conducting the incubation experiment, it was observed that the application of sulfur pulp led to a statistically significant (and proportional to the dose) increase in the content of available sulfur in soil. Application of waste caused a decrease in soil pH and an increase in the mobility and availability of Zn, Cd and Mn (extracted with 0.01 mol • dm–3 CaCl2). In relation to soil without waste, more Zn, Cd and Mn (by 4–51%, 9–24% and 0.1–31%, respectively) was determined. Liming reduced the acidifying effect of the introduced waste – after 150 days, only soil with the highest dose of sulfur pulp was characterized by a statistically significantly lower pH than the soil without the waste addition. An increase in the rate of sulfur oxidation was also observed – after 150 days of the experiment, more sulfate sulfur (by 14.4–34.5%) was determined, with respect to treatments of the unlimed series. A considerably lower content of Zn, Cd and Mn was determined in the limed soil than in the unlimed one. Regardless of waste dose and date of analysis, the soil contained a trace content of mobile forms of Cu, Cr, Ni and Pb.