SPECIATION OF METALS IN SEWAGE-SLUDGE FOR AGRICULTURAL USES

A study carried out on sewage sludge samples collected at an urban was te-water processing plant located in Zaragoza (Spain) is reported, The concentrations of metals (Cd, Co, Cr, Cu, Ca, K, Fe, Mg, Mn, Ni, Na, Pb and Zn) and agronomic parameters were determined, The speciation of metals based on the sequential extraction scheme proposed by Tessier et al. is reported, Principal component analysis was applied to the re sults obtained and the correlation factors are discussed, The concentr ation of heavy metals is lower than that established by European legis lation, Heavy metals are mainly associated with the mineral fraction a nd consequently they show a low availability index.