BIOLOGICAL DECONTAMINATION OF HEAVY-METAL POLLUTED SEDIMENTS - STUDY ON INFLUENCE OF SUBSTRATE, TOTAL SOLID CONCENTRATION AND TEMPERATURE

The process of bacterial removal of heavy metals from sewage sludge has been applied to decontaminate river sediments. The influence of the following factors has bee, studied in a batch process (0.51): substrate concentration (FeSO4.7H2O), concentration of total solid (TS) in the sediments and the operating temperature. No relations between solubilization of metals (Cu, Pb) and substrate concentration (5, 10 and 20% FeSO4.7H2O) were found with the exception of lead. A 30% FeSO4.7H2O concentration decreased Pb solubilization. As the solubility product of PbSO4(s) is suspected of controlling the solubility of lead, higher sulfate concentration in solution may have decreased soluble Pb (at 30% FeSO4.7H2O). Solubility of metals also decreased with increases in TS. ORP and pH were significantly correlated in %TS (r2 = 0.94 and 0.84 respectively). A decrease of temperature from 21-degrees-C to 10-degrees-C diminished Cu solubilization efficiency without influencing Pb solubilization. A temperature coefficient (Q10(10-21C)) of 1.93 has been found for Cu.