Effect of Tannins on Phosphate Removal Using Alum


Abstract: Phosphate removal from wastewater can be achieved either through chemical removal, advanced biological treatment or a combination of both. Chemical phosphate removal involves the addition of aluminum, iron and calcium salts to achieve phosphate precipitation. The effectiveness of tannin obtained from valonia as a coagulant aid was investigated using various doses, together with Al_{2}(SO_{4})_{3} in a jar test. Jar tests were conducted in a synthetic water containing varying concentrations (1-20 mg/L) of phosphate. Al_{2}(SO_{4})_{3} was effective in the removal of phosphate from synthetic water. Both (Al_{2}(SO_{4})_{3} + tannin) and (Al_{2}(SO_{4})_{3} + AN913, synthetic anionic polyelectrolyte) were more effective than Al_{2}(SO_{4})_{3} alone. Tannin and AN913 as coagulant aids gave similar phosphate removals in cases of high phosphate concentrations (10-20 mg/L). However, tannin was more effective than AN913 in cases of low phosphate concentrations (1-5 mg/L).

Keywords: Tannins, Polyelectrolyte, Coagulant aid, Phosphate removal, Chemical precipitation

Full Text: PDF