Statistical Modeling and Optimization of Coag-Flocculation Process of Phosphate Removal from Aqueous Solution Using Ox-Eye Seed (Chrysanthemum leucanthemum) as Coagulant

Abstract

Excess deposits of phosphorus into surface waters have caused a lot of devastating effects on both human and aquatic lives and, of course, ecosystem disruption. Ox-eye seed (OES), an agricultural biomass, has been explored as a coagulant to remove phosphorus from aqueous solution through coag-flocculation process. The seeds were prepared into a coagulant and a proximate analysis was carried out on the prepared OES. Nephelometric analysis was employed to investigate the effects of settling time, coagulant dosage and pH on phosphate removal efficiency of OES. The process parameters were optimized using Response Surface Methodology. OES’s performance was compared with Alum’s, a conventional coagulant, and the results obtained reveal Alum as having a global minimum of zero turbidity, global optimum values for pH (7.4103) and dosage (301.6501mg/l) but a local optimum of 80min for settling time, while the optimum operating parameters for OES are 7.3740 (global), 500mg/l (local), 80min (local) and 11.2266mg/l (local) for pH, dosage, settling time and turbidity respectively. It is evident that, by increasing settling time and dosage , OES can effectively compete with Alum. The main attribute to effective performance of both OES and Alum is pH. The interactions pH-dosage and pH-settling time are significant. The model accuracy is confirmed by the values of R2 >0.99 and is validated by the closeness of the experimental data to the predictions. Keywords: Phosphorus, wastewater, turbidity, Coagulant, ox-eye, flocculation