Flower waste: a novel candidate for the removal of chromium from tannery effluent

Chromium is a highly abundant element and is present in its ionic form in most of the effluent streams. As a consequence, improved and innovative methods of waste water treatment have been developed to remove these metal ions. In this work we used flower waste biomass as a biosorbent to remove Cr from tannery effluent through column experiments. The sorption capacities of biosorbent (fine, coarse and rough grades) were also evaluated by employing chemical pretreatments viz., sodium hydroxide, acetic acid, glutaraldehyde and hydrogen peroxide. The order of percentage removal of Cr using the above pretreatments is: 10% hydrogen peroxide < raw powdered-FWB < 2% glutaraldehyde < 10% acetic acid < 0.1 N sodium hydroxide. Among the different grades of biosorbents used, fine grade adsorbed more Cr (70%) than that of coarse (64%) and rough (62%) sorbents. The removal percentage of Cr from tannery was analysed by using atomic absorption spectroscopy, the functional groups which are responsible for adsorption was examined by Fourier transform-infrared spectroscopy and the amorphous behaviour of FWB facilitating metal biosorption was indicated by the X-ray diffractogram. This study showed that pretreated flower waste biomass is a potential sorbent of Cr, which could be successfully used to reduce the Cr content in tannery effluent.