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 Al2(SO4)3 in a jar test. Jar tests were conducted in a synthetic water containing varying concentrations (1-20 mg/L) of phosphate. Al2(SO4)3 was effective in the removal of phosphate from synthetic water. Both (Al2(SO4)3 + tannin) and (Al2(SO4)3 + AN913, synthetic anionic polyelectrolyte) were more effective than Al2(SO4)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).

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