Abstract

Successful decolourisation and degradation of textile dyes was achieved in a biosulphidogenic batch reactor using biodigester sludge from a local municipality waste treatment plant as a source of carbon and microflora that augmented a sulphate reducing bacteria (SRB) consortium. Orange II (O II) was decolourised by 95 % within one day (24 h) producing 1-amino-2-naphthol and stoichiometric quantities of sulphanilic acid. The latter was degraded steadily (from ≈ 290 to 43 µM) over 20 days while 1-amino-2-naphthol disappeared from the reactor within two days. Other azo dyes, Reactive black 5 (RB 5), Reactive red 120 (RR 120), Remazol Brilliant violet 5R (RBV 5R), an anthraquinone dye Reactive blue 2 (RB 2) and an industrial azo dye mixture (Da Gama Textiles, King Williams Town, South Africa) were successfully degraded with the exception of Amido black 10B (AB 10B). The Orange II degrading cultures were freeze dried to investigate the feasibility of commercialising a powdered mixed starter culture for textile effluent bioremediation, but this decreased the dye degrading efficiency. Therefore bioremediation of textile effluent with sludge and SRB can concomitantly treat two wastes while providing a cheaper alternative of the carbon source.  . However, the fate of more aromatic amines needs to be investigated before full commercialisation of the process.

Key words: Bioremediation, textile effluent, 1-amino-2-naphthol, sulphanilic acid, sulphate reducing bacteria (SRB), azo dye, biosulphidogenic.