Decolourisation and degradation of reactive blue 2 by sulphate reducing bacteria (SRB) and zero valent iron in a biosulphidogenic reactor

Abstract

This work was performed to determine the influence of heat treatment on sewage sludge and addition of zero valent iron (ZVI) on the degradation and decolourisation of an anthraquinone dye, reactive blue 2 (RB 2). A consortium of sulphate reducing bacteria (SRB) in a biosulphidogenic batch reactor with biodigester sludge was used. The latter supplied carbon and augmenting microorganisms. Reactors with heat treated sludge were outperformed by those with unheated sludge for the larger part of the reactor life span. A 75% decolourisation efficiency was achieved within 24 h of inoculation when 4 g ZVI/l were added in an SRB reactor with unheated sludge as opposed to 59% colour removal after four days in the same reactor without ZVI. However, decolourisation was also noted in the presence of ZVI alone, indicating existence of chemical reaction between ZVI and RB 2.

Key words: Decolourisation, degradation, reactive blue 2, zero valent iron, sulphate reducing bacteria, sulphidogenic.