Effect of Biochar on Lead and Cadmium Uptake from Applied Paper Factory Sewage Sludge by Sunflower (Heliantus annus L.)

Application of sewage sludge in agricultural lands as a fertilizer is a suitable selection for solving management problems of sewage sludge disposal, besides its economic benefits. One of the main limiting factors to use sewage sludge is its high content of heavy metals such as lead and cadmium. Biochar with organic ligands can create complex with heavy metals and makes them immobile in soil, and reduces their transport to plants. The aim of this study was to investigate the influence of the Biochar on lead and cadmium uptake from a Paper Factory sewage sludge by the Sunflower (Heliantus annus). For this purpose, a factorial greenhouse experiment as a complete randomized design with three replications was conducted. Four levels of sewage sludge with 0, 15, 20 and 25 (g kg-1 of the soil) and four levels of Biochar with 0, 5, 10 and 15 (g kg-1 of the soil) were used in order to investigate the sewage sludge influence. The results showed that the use of sewage sludge led to a significant increase of the lead and cadmium concentrations in the Sunflower shoots and roots. The results also showed that application of Biochar led to a significant decrease (at 1% probability level) of lead and cadmium concentrations at the shoots and roots of Sunflower.