The same as for triphenylmethane dyes diazo Evans blue was better removed by strain Sz6 isolated from small wastewater treatment plants purifying mainly domestic wastewater. Triphenylmethane and azo dyes commonly used in textile colouring processes are released during cloth washing and that is why colourant concentration in domestic wastewater can be high. Strain Sz6 seems to be better adapted to higher concentration of triphenylmethane brilliant green and azo Evans blue than SDz3.