Abstract:

 Anaerobic activated sludge was used to cultivate arsenicresistant denitrificator in laboratory. The acclimated bacteria were incubated with nutrient solution and Asadsorbing ferrihydrite in anaerobic condition to investigate the geochemical behavior of As adsorbed on ferrihydrite. The concentrations of Fe, Mn, NO-3and As species in suspensions were monitored during the incubation. The acclimation results show that the denitrificator in the anaerobic activated sludge can abide the As(V) in the solution, and its denitrification intensity was less affected by As when its concentration is less than 500 μg/L. In the batch incubation with addition of Asadsorbing ferrihydrite, the presence of arsenicresistant denitrificator caused an increase in concentrations of Fe and Mn, a decrease in concentrations of NO-3 and As, and a high ratio of As(III) to the total As. This indicates that both the reductive dissolution of ferrihydrite and the reductive desorption of As(V) occurred in the batches incubated with arsenicresistant denitrificator and Asadsorbing ferrihydrite. The decrease in As concentration was caused by the readsorption of the released As on the new adsorption sites of the partially dissolved ferrihydrite because of high ratio of ferrihydrite to the solution.

Key words:

Key words: Activated sludge; As species; denitrification; As removal; mobilization