Another common component is the azo bond. Azo bond is present in ten out of twelve dyes and is primarily responsible for showing the colour. Finally, the presence of sulphonyl groups, benzene rings and hydrophilic side groups on these benzene rings will alter the colour. Knowing that there are similarities between the dyes makes it easier to create a treatment process.
Several physical and chemical methods exist for treating dyes. However, some processes are expensive and produce a lot of waste. Treatment by microbes offers an interesting alternative. Some Microalgae, bacteria and fungi contain proteins which can break the azo bond and form intermediate products. Unfortunately, additional expensive products are needed when using these proteins, and the intermediates are often toxic. However, the good news is that intermediates with sulphonate groups are normally harmless to human.