The impact of increased oxygen conditions on heavy metal flocculation in the Sefidrud estuary.

Similar to natural filters, estuaries are capable of removing considerable amounts of heavy metal from rivers that flow into saline water environments by turning the metal into flocs. The research objective was to investigate the self-purification potential of estuaries in removal of metal by flocculation processes. Hence, flocculation of metal was studied experimentally in 5 aquaria with varying salinity levels. Subsequently, experiment was repeated while dissolved oxygen increased. Results indicated that at higher dissolved oxygen, the flocculation rates of Mn, Ni, and Pb increased by 9%, 20%, and 26%, respectively. However, Zn and Cu showed 23% and 26% of decrease in flocculation rate, respectively. In the analysis of the relationship between oxidation reduction potential and estuarine water quality it was found that ORP escalated with an increase in the dissolved oxygen. This finding suggests that ORP can be used to govern the potential of flocculation processes at estuarine zone.