Nowadays, the classification of industrial solid wastes is not based on risk analysis, thus the aim of this
study was to compare the toxicity classifications based on the chemical and ecotoxicological characterization
of four industrial sludges submitted to a two-step stabilization/solidification (S/S) processes. To
classify S/S products as hazardous or non-hazardous, values cited in Brazilian chemical waste regulations
were adopted and compared to the results obtained with a battery of biotests (bacteria, alga and daphnids)
which were carried out with soluble and leaching fractions. In some cases the hazardous potential
of industrial sludge was underestimated, since the S/S products obtained from the metal-mechanics and
automotive sludges were chemically classified as non-hazardous (but non-inert) when the ecotoxicity
tests showed toxicity values for leaching and soluble fractions. In other cases, the environmental impact
was overestimated, since the S/S products of the textile sludges were chemically classified as non-inert
(but non-hazardous) while ecotoxicity tests did not reveal any effects on bacteria, daphnids and algae.
From the results of the chemical and ecotoxicological analyses we concluded that: (i) current regulations
related to solid waste classification based on leachability and solubility tests do not ensure reliable
results with respect to environmental protection; (ii) the two-step process was very effective in terms of
metal immobilization, even at higher metal-concentrations. Considering that S/S products will be subject
to environmental conditions, it is of great interest to test the ecotoxicity potential of the contaminants
release from these products with a view to avoiding environmental impact given the unreliability of
ecotoxicological estimations originating from chemical analysis.
Nowadays, the classification of industrial solid wastes is not based on risk analysis, thus the aim of thisstudy was to compare the toxicity classifications based on the chemical and ecotoxicological characterizationof four industrial sludges submitted to a two-step stabilization/solidification (S/S) processes. Toclassify S/S products as hazardous or non-hazardous, values cited in Brazilian chemical waste regulationswere adopted and compared to the results obtained with a battery of biotests (bacteria, alga and daphnids)which were carried out with soluble and leaching fractions. In some cases the hazardous potentialof industrial sludge was underestimated, since the S/S products obtained from the metal-mechanics andautomotive sludges were chemically classified as non-hazardous (but non-inert) when the ecotoxicitytests showed toxicity values for leaching and soluble fractions. In other cases, the environmental impactwas overestimated, since the S/S products of the textile sludges were chemically classified as non-inert(but non-hazardous) while ecotoxicity tests did not reveal any effects on bacteria, daphnids and algae.From the results of the chemical and ecotoxicological analyses we concluded that: (i) current regulationsrelated to solid waste classification based on leachability and solubility tests do not ensure reliableresults with respect to environmental protection; (ii) the two-step process was very effective in terms ofmetal immobilization, even at higher metal-concentrations. Considering that S/S products will be subjectto environmental conditions, it is of great interest to test the ecotoxicity potential of the contaminantsrelease from these products with a view to avoiding environmental impact given the unreliability ofecotoxicological estimations originating from chemical analysis.
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