Removal of Reactive Orange 3 dye from aqueous solution by biosorption technology

The biosorption process has found numerous applications due to low cost, availability, biosorbent reuse, and utilization of excess sludge from wastewater treatment facilities. The aim of the present study was to evaluate the efficiency of dried activated sludge in removing Reactive Orange 3R dye. For this experimental, laboratory study, dye solutions were prepared in three concentrations: 50, 100, and 150 mg/L. The solutions were then subjected to adsorbent in weights 0.2, 0.4, 0.6, 0.8, and 1.0 g for various durations (0.5, 1, 1.5, 2, 2.5, and 3 hours) in different pH levels (4, 7, and 12). Data was analyzed using Excel software. Increasing contact time from 0.5h to 3h, the dye removal efficiency increased from 56% to 76%. When the weight of the biomass increased from 0.2g to 0.8g, the dye removal efficiency increased from 58% to 72%. High initial iron concentration had an adverse effect on iron removal efficiency. Increasing initial dye concentration from 50 to 150 mg/L decreased iron removal efficiency from 71% to 62%. Freundlich isotherm models could describe the adsorption equilibrium of the dye onto the activated sludge. Freundlich isotherm represented a better correlation compared to other isotherms (R2>0.952). Also, second-order models fit well with experimental data (R2>0.979). This technology for dye removal from industrial wastewater, in addition to the optimal use of biomass from wastewater, can help resolve the environmental problem of wastewater dye excretion. (Quarterly Journal of Sabzevar University of Medical Sciences, Volume 19, Number 2, pp.127-135).