FINE BUBBLE AERATION AT SEDIMENT-WATER INTERFACE INHIBITS RELEASE OF HEAVY METALS IN SEDIMENT FROM

The effects of fine bubble aeration at the sediment-water interface (SWI) on the fraction distributions and release patterns of heavy metals (Pb, Cu, Ni, and Cr) in sediment from a substantially polluted urban river were studied in a simulation experiment. The dissolved oxygen concentration and pH of the overlying water increased, along with a considerable increase in the oxidation-reduction potential of surface sediment, according to the findings. Furthermore, fine bubble aeration at SWI considerably changed the distributions of heavy metal fractions, resulting in reduced acid-extractable metal concentrations and a higher proportion of the residual fraction. The proportion of residual Ni fraction increased from 39.5 percent before treatment to 55.0 percent after treatment, indicating that Ni fractions were sensitive to fine bubble aeration. In comparison to the non-aeration control, aeration treatment increased heavy metal content in sediment porewater. However, as the length of treatment was extended, this rise was gradually reduced. The heavy metal content of sediment pore water decreased considerably after 10 days of treatment, particularly Ni. At SWI, fine bubble aeration reduced acid-volatile sulphide (AVS), but did not necessarily enhance heavy metal release from surface sediment. The findings show that tiny bubble aeration at SWI reduces heavy metal bioavailability and danger of release in river sediment. Dynamic variations in the environment's physiochemical variables, including as dissolved oxygen, pH, and oxidation-reduction potential in the overlaying water and surface soil, are primarily responsible for this suppression.

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