Atenuação de metais pesados pelo processo de biossorção em reatores e estabilização por solidificação do resíduo.

Abstract

The main purpose of this paper is to diminish synthetic sewage contaminants containing the heavy metals, lead and cadmium, through biosorption process using sludge of a UASB reactor as a biosorbent and then evaluate the technical feasibility for using stabilization by solidification to treat reactor substrate. The biosorbent (sludge of sanitary sewer) was added in three fixed bed upflow biosorption reactors, two of the reactors were fed with a synthetic sewage prepared with distilled water and metal with 50 mg.L"' concentration to promote the biosorption process between substrate and metallic ions and the third reactor was fed with distilled water. The reactors sewages were submitted to pH analysis, conductivity, total alkalinity and volatile fatty acids, and atomic absorption spectroscopy. The biosorbent samples were characterized by analysis of pH, humidity, total solids and their fractions, leaching, solubilization and x-ray fluorescence by dispersive energy testing. The results from reactors sewage were statistically analyzed. Biosorbent analysis before biosorption process showed cadmium and lead low concentrations compared to the default limit, and one could classify it, related to cadmium and lead, as class 1TB. Time factor did not influence pH in reactor 2 or 3. Metal removal occurred in basic pH and it did not affect biosorption, since the results showed high levels of cadmium (II) and lead (II) removal. It was obtained an average removal of 98,6% for cadmium (II) and 98,8 for lead. The x-ray fluorescence test showed the presence of used metals on the work after biosorption process in the reactors biosorbents, where the biosorbent showed cadmium in its composition and a lead percentage, which confirms metal retention by the biosorbents. Through E/S and the results obtained on the leaching test it was possible to convert the solid residue of the the biosorption process, from class I (dangerous) to class IIA - non inert (not dangerous).