Title: Phycoremediation of tannery waste using cyanobacteria as bioreagent with special reference to Nano Chromium formation

Iman Dey

University of Calcutta, India


Miss. Iman Dey completed her graduation in Botany in the year of 2014 from Scottish Church College, the University of Calcutta and her rank was Fifth. She completed her post graduation from University of Calcutta in the year of 2016. She then joined Phycology Laboratory of the University of Calcutta under guidance of Prof. Ruma Pal.


Tannery wastewater carries heavy pollution load due to high organic and inorganic contents, highly colored compounds and toxic metallic substances. Characterization of this water from inlet point showed high level of BOD (1234.33 mg/L), COD (1706.64 mg/L), Total Chromium (56.85 mg/L), TDS (6984mg/L), sulfide (140.8 mg/L) and ammonium (134.5 mg/L). These values were several folds above the standard limits set by ISI (2000). From the present investigation, it was found that Cyanoprokaryotes efficiently removed toxic metals on one hand and nutrients on the other hand from tannery wastewater. In this investigation, marine Cyanoprokaryote Phormidium valderianum was grown in various dilutions including raw tannery wastewater of leather complex, Eastern India in open tank (4.0 L with a depth of 15 cm and the breadth of 25 cm). The cyanoprokaryote was found to be efficient in removing nitrate and phosphate by 90% and 76% respectively from raw wastewater. Dissolved oxygen increased by 10 folds in all dilutions of Tannery Wastewater. The efficiency of ammonia removal (84%) was found to be maximum in case of 50% dilution. The growth performance of exposed biomass was measured in terms of dry weight and Chlorophyll content. Surface topography and distribution of elements adsorbed in algal biomass was analyzed with SEM and EDAX study.  The functional groups of the algal biomass before and after treatment were investigated through FTIR spectroscopic study. Atomic Absorption Spectroscopic analysis of treated algal biomass showed a significant amount of chromium removal from wastewater and formation of nano chromium was determined using UV-VIS spectra in an in-vitro exposure of algal biomass to potassium dichromate solution. The Scanning and Transmission Electron Microscopy study revealed the cluster of rod-shaped nano chromium formed by the cyanobacterial biomass. Detail characteristic features of nano chromium would be discussed.