Introduction

With increasing awareness among the general public of the problems of water pollution has come a realization among effluent dischargers that the colour in effluents represents a problem in itself. Colourless effiuents are less visible, attract less attention and cause less concern than coloured effiuents. This is despite the fact that often chromophores may be present in very small amounts and may pose no significant threat to the environment, other than turning a river red or purple! Having said this, there can be significant problems of toxicity associated with some chromophores (Brown & De Vito, 1993) and many coloured effluents contain damaging materials in addition to chromophores. The focus of this contribution is the removal of colour from effluents, and in particular how wood-rotting fungi can be used for this purpose. It is perhaps useful to consider briefly what alternative processes are available before examining the possible roles of fungi.

The main processes used for colour removal are physicochemical and chemical treatments (Laing, 1991; Cooper, 1995) all of which have some drawbacks. Physicochemical treatments include flocculation and coagulation, adsorption, ion exchange, ultrafiltration and reverse osmosis. These processes (apart from expense) have the problem that contaminant chemicals are not destroyed; they are simply removed from effluents and relocated elsewhere – usually disposed of to landfill or by incineration. Chemical processes mainly involve bleaching using chlorine-based chemicals, ozone or peroxides.