An over review on recently developed techniques, mechanisms and intermediate involved in the advanced azo dye degradation for industrial applications

•The current article reviews about introduction to azo dyes, the various techniques involved for the bio-degradation and photocatalysis degradation of azo dyes including advantages and drawbacks of the each techniques.•This review articles highlights necessity to develop eco-friendly and cost-effective technique that may address the drawbacks of existing waste water treatment process.•High lights the mechanism of dye removal and confirmation techniques of nano-alloy catalysts.•Gives general idea to young researcher about relation between band gab energy and photocatalysis.