Absorçäo de metais pesados do lodo de esgoto pelo feijoeiro (Phaseolus vulgaris L.) / Heavy metal uptake of the sewage sludge by bean plants (Phaseolus vulgaris L.)

ABSTRACT

Toxicity and uptake of heavy metals of sewage sludge by beans (Phaseolus vulgaris L.) were evaluated in green house experiments. Treatments consisted of 1,0; 2,0 and 5,0 per cent (m/m) of dry sewage sludge, collected from Londrina (Bom Retiro and ETE-Sul) and Curitiba (ETE-Belém and RALF). Bean (variety IAPAR 57) was sown three times at 0, 120 and 240 days after the treatment have been applied. Contents of Cd, Cr, Co, Cu, Ni, and Pb in bean tissues cultivated with 5,0 per cent (m/m) of all sewage sludge were similar to the control and Ba contents were reduced by increasing the quantity of sewage sludge in the soil. The Zn content in tissue bean increased from 86 mg kg -1 of contrrol to 462 mg kg-1 by applying 5 per cent (m/m) of sewage sludge in soil, but plant beans did not show toxicity symptons. The addition of 5 per cent (m/m) of sewage sludge increased Mn content in plants, from 193 mg kg-1 of control to 1.960 mg kg -1, showing toxity in bean leaves when the contents were more than 500 mg kg-1. The addition of sewage sludges in soils increased only avaiable Zn carbonate and Cu organic species