The Optimal Performances of Starches from two Cassava varieties as Bioflocculants for the Treatment of Textile Wastewater

The optimal performances of starches produced from two cassava varieties–Manihot aipi (SMA) and Manihot palmate (SMP) as bioflocculants for the treatment of textile wastewater were investigated in this study. The central composite rotatable design was used to investigate the effects of varying dosages of each cassava starch, wastewater-pH, and settling time on the turbidity removal from the wastewater with alum as the primary coagulant. Highly significant second-order multilinear quadratic regression models were developed from the experimental data, resulting in a very high coefficient of determination (r2) values of 0.999 for the SMA and 1.000 for the SMP models. The optimum cassava doses of 50 and 150 mg/L, pH-values of 6.5 and 8.0, and settling times of 95 and 77 minutes led to predictive maximum turbidity removals of 98.35 and 88.87%% with desirability functions of 0.95 and 0.63 for the SMA and SMP, respectively. The corresponding observed turbidity removal recorded at these optimum conditions were 88.72% and 88.52% for the SMA and SMP, respectively. At these optimum conditions, there was no significant difference between the predicted and observed turbidity removed from the wastewater at a p≤0.05 significance level. Verification of the Jar tests showed a good agreement between the experimental data and the models and confirmed that the SMA was superior to the SMP in supporting the alum to remove turbidity from the textile wastewater. As a result, the study revealed that Manihot aipi starch has more flocculating capability than Manihot palmate for the treatment of textile wastewater.