Sewage sludge application to first year willows (Salix viminalis) growth and heavy metal bioaccumulation

Abstract

Management of sewage sludge is a growing problem worldwide. The use of sewage sludge as fertilizer is increasing. The main aim of the study was to investigate the effects of sewage sludge application on first year willows (Salix viminalis L.) and determine the accumulation of heavy metals in plants. Plants were exposed to 1; 2.5; 5; 10; 15 kg m-2 of sewage sludge under field conditions. Willows (Salix viminalis) were grown in the field for six months. Effects on plant growth (stem height, underground and aboveground biomass) and the heavy metal (Cu, Cd, Zn, Pb) accumulation in the roots, stems, leaves and bark was determined. Sewage sludge application enhanced the growth of willows (Salix viminalis). Stem height of willows grown in soil treated with sludge were by 15 - 31% higher than those grown in control plots. Sludge application has led to higher biomass production. The biomass of stems and roots were by 26 -61 % and 36 - 62%, respectively, higher than that of control plants. Sludge application resulted in increases heavy metals concentrations in soil and willows. Metals concentrations were plants tissue and sludge application rate dependent. The highest bioconcentration factor was detected for Cd. Due to uptake of heavy metals by willows, the concentrations of Cu, Zn, Cd in soil (at 20 and 40 cm depth) after experiment were significantly reduced.