Bioremediation of Cr(VI) Using Live Cyanobacteria: Experimentation and Kinetic Modeling

The removal of Cr(VI) from synthetic wastewater using living cyanobacteria Limnococcus sp. was examined. Characterizations of the native and metal loaded cells were done using scanning electron microscopy, energy-dispersive spectroscopy, and Fourier transform infrared spectroscopy. The operating condition was optimized using one-factor-at-a-time analysis. Maximum Cr(VI) removal (63.23%) was achieved with initial Cr(VI) concentration 20mg/L, pH 9.0, inoculum size 10% [volume per volume (v/v)], and incubation period 16days. The distribution of Cr(VI) on the cell surface through biosorption and in the intracellular space through bioaccumulation were also determined. The logistic model was used to design the variation of growth of the biomass with time. Maximum specific growth rate (m) was determined to be 0.31/day. The maximum carrying capacity of the synthetic wastewater observed was 0.857g/L with initial Cr(VI) concentration of 20mg/L. An empirical power-law model was also developed to predict the interactive effect of the initial Cr(VI) concentration, pH, inoculum size, and incubation time with the cell dry mass (CDM), percentage removal of Cr(VI), and lipid content.