ABSTRACT
This paper reports the preliminary results obtained by a sequential extraction method based on Rudd's procedure that can be used to determine various chemical forms of heavy metals present in sludge. The impact of heavy metals present in sewage sludge for agricultural use is determined by their mobility and bioavailability. These parameters heavily depend on the chemical forms of the metals present. This study proposes a procedure that may be adopted in further studies for a more appropriate normative than the present European Economic Community Directive no. 278/86. By providing data on both metal mobility and total heavy metal concentration, the researcher may draw adequate guidelines that reflect the true environmental risk involved in the use of sludge for agriculture.
Subject(s)
Chemistry Techniques, Analytical/methods , Metals/isolation & purification , Sewage/analysis , Agriculture/legislation & jurisprudence , ItalyABSTRACT
To evaluate the fertilizing and polluting potential of sewage sludge and to establish whether the latter limits the former or not, sludge must be characterized, application rates chosen, and sludge effects monitored. This work emphasizes that chemical analysis aimed at total metal quantification cannot by itself ensure reliable answers about the agricultural value of sludge. The EEC directives about heavy metals in sewage sludge provide the total content limitation of each element without taking into consideration the respective fractions of metals present in their free state constituting the chemical state most directly related to sanitary risk. To evaluate the role of the Environmental Impact Assessment (EIA) in a such disposal system, a scheme is proposed.
