... Azo dye decolorization in a down flow aerobic biofilm reactor with Opuntia imbricata as support . ... This paper describes the use of a down flow column aerobic reactor packed with Opuntia imbricata (Natural Support) in the degradation of textile dye and the COD removal. The kinetic results showed that the velocity of COD removal is a function of HRT and the initial velocity of this removal increased with HRT. ... Moscow University Chemistry Bulletin . 2006, Vol. ...