Degradation of chlorinated dioxin in denitrifying activated sludge from leachate treatment plant of a landfill

Abstract

The degradation rate of dioxins added to the activated sludge from a leachate treatment plant of a landfill under denitrification conditions was estimated using six bioreactors. Over 99% of the added dioxins (600 ng) were degraded within 7 days. Furthermore, continuous cultivation was carried out for 1 month. The activated sludge degraded 600 ng of dioxins (that is, all of the added dioxins) placed in each reactor every 7 days, and this activity was maintained for 35 days. Under aerobic conditions with this sludge, the dioxins were not degraded in 7 days, but 90% of the 600 ng of dioxins was degraded in 35 days. The high level of activity observed in the present study may only occur under anaerobic conditions, especially under denitrifying conditions.