Copper remediation by Eichhornia spp. and sulphate-reducing bacteria

Eichhornia spp. biomass was collected from Chandola Lake, Ahmedabad, Gujarat, India. Point of zero charge of the biomass was pH 7.3. Flask study showed pH 5 and 2-3 h contact time as optimum conditions for copper sorption with 67.25% copper removal. At the end of 24 h of contact time, copper removal reached to 85.0%, from 100 ppm copper containing solution. Copper loading capacity of the biomass ranged between 9.9 and 28.5 mg g−1 of biomass. To understand the interaction among pH, temperature, presence of nickel and zinc in the system, 24 factorial experiment was performed. Under the experimental conditions pH and interactions between pH-nickel, temperature-pH and temperature-pH-nickel-zinc were found to be significant with 60-74.7% copper removal. Langmuir isotherm was better fit as compared to Freundlich isotherm and pseudo-second order equation gave R2 of 0.999 for biosorption kinetic of Eichhornia biomass. Reactor study showed 90% overall copper removal from 24 L of copper containing waste studied and sulphate-reducing bacteria played a significant role. SEMquant element analysis showed increase from 41.66% to 53.93%, 1.02-19.73% and 0.0-12.39% of chloride, aluminium and copper respectively in the loaded biomass as compare to unexposed biomass.