Synchronous attenuation of metal ions and colour in aqua stream using tannin-alum synergy

► Metals could be removed from the aqua system without discolouration by phenolics. ► Concurrent removal of colour and metal ion occurred at lower alum dose. ► Concurrent removal of colour and metal ion occurred over wide pH range. ► FTIR analysis showed interaction between the tannin -OH group and the metal ions.