Comparative study on the removal of a local scrap iron tannery made dye from wastewater using alum and rice husk

This work was aimed at removing a local scrap iron dye from tannery wastewater using alum and rice husk. Contact time (0 to 60 min; wastewater dye concentrations: A0 = 0.244 and A0 = 0.48 for alum; A0 = 0.213 and A0 = 0.045 for rice husk), pH (2 to 10; wastewater dye concentration of A0 = 0.045 for rice husk and A0 = 0.073 for alum), mass of adsorbents (0.05 to 1 g; wastewater dye concentration of A0 = 0.184 for alum, A0 = 0.057 for rice husk), temperature (25 to 60 °C; wastewater dye concentration of A0 = 0.079 for rice husk and A0 = 0.048 for alum) and mixtures of the two adsorbents (wastewater dye concentration of A0 = 0.057 and A0 = 0.217) were used to evaluate the effectiveness of these adsorbents in removing color from a local Maroua tannery wastewater. Equilibrium was reached in 10 min with a removal of 54.16% for alum and in 5 min with a removal of 66.66% for biomass. 100% elimination of color was obtained at pH 2 and 4 for rice husk and 73–76% for alum. But the mixture of 0.2 g of alum and 0.1 g of rice husk gave removal rate of 95% with a less concentrated solution against 74.84% for the mixture of 0.1 of alum and 0.2 g of rice husk with concentrated solution. Results of this study shows that substitution or complementing alum a synthetic chemical with rice husk, a biomass highly available at almost no cost can be very efficient in the treatment of tannery wastewater containing dye in a low cost process.