Although in this step the dyes undergo a process of dilution, the environmental impact is not eliminated due to the fact that triphenylmethane dyes increase the chemical oxygen demand (COD), biological oxygen demand (BOD), solids content, water color, and can cause acute toxicity at different trophic levels (Przystas et al.
These chemical characteristics determine that triphenylmethane dyes are more resistant to biological degradation than other families of dyes and explains how biodegradation byproducts of these dyes can form intermediaries with more toxicity than the initial compound.
For the biological removal of triphenylmethane dyes, there have been several successful studies using aerobic and anaerobic bacteria.
On the other hand, mycelia morphology of Pleurotus ostreatus (thin hyaline hyphae, long and pellets) and spore production are additional functional aspects that favor the removal of triphenylmethane dyes.
Biodegradation and decolorization of triphenylmethane dyes by Staphylococcus epidermidis, Desalination, 260: 137-146, 2010.
Metabolites from the biodegradation of triphenylmethane dyes by Trametes versicolor or laccase, Chemosphere, 75: 1344-1349, 2009.
Decolorization of triphenylmethane dyes by wild mushrooms, Biotechnology and Bioprocess Engineering, 19: 519-525, 2014.
Biological removal of azo and Triphenylmethane dyes and toxicity of process by-products, Water Air Soil Pollution, 223: 1581-1592, 2012.
They are: Erythrosin included in the class of xanthene dyes; Blue indigotine included in the indigotin class of dyes, Patent Blue V, Fast Green and Brilliant Blue in class of triphenylmethane dyes
, Bordeaux Red, Ponceau 4R, Red 40, Azorubine, Tartrazine Yellow and Sunset Yellow, included in the class of azo dyes (POLONIO; PERES, 2009).