The Evaluation of the Phytoremediation Potential of the Energy Crops in Acid Soil by Sewage Sludge Fertilization

Abstract

Phytoremediation is a green technique being increasingly used worldwide for various purposes, including sewage sludge contaminated by heavy metals. Most plants proposed for this technique have high nutrient demands, and fertilization is often required to maintain soil fertility and nutrient balance. In this context, sewage sludge could be a valuable source of nutrients (especially N and P) and water for plant growth. The main aim of this study was to assess the phytoremediation potential of selected energy plants, aspects of its increase, as well as contamination risks. Three treatments were used: unfertilized soil and the application of 45 and 90 t ha−1 of sewage sludge. The experiment was performed in common osier and cup plant growing sites. Cr, Ni, Pb, Cu, and Zn contents in the soil tended to rise steadily when the amount of sewage sludge increased from 45 to 90 t ha−1. Heavy metal concentrations in the soil were ranked as follows: Zn > Cr > Ni > Pb > Cu. Cr and Pb concentrations increased by 22.5% and 37.4% in 2020, respectively, compared to those in 2017, whereas Cu concentrations declined by 44.4%. Cu and Ni were significantly reduced by common osier while Pb and Zn were reduced by cup plant. A moderate potential ecological risk due to Cr, Ni, Cu, Pb, and Zn was observed in soils. The data can be used to estimate the suitability of the soil treated by sewage sludge for added value development in line with circular economy principles.

Keywords

• heavy metals
• sewage sludge
• acid soil
• soil quality
• energy crops
• ecological risk indices