A Study on the use of tanins, obtained from oak acorns (Valonia) as natural polyelectrolyte in water treatment

A STUDY ON THE USE OF TANNINS, OBTAINED FROM OAK ACORNS (VALONIA), AS NATURAL POLYELECTROLYTE IN WATER TREATMENT SUMMARY Keywords: Natural polyelectrolytes, synthetic polyelectrolytes, tannin, AN913, aluminium sulphate, coagulation, flocculation, turbidity removal, phosphate removal. In this study, it was investigated whether or not a tannin, a natural polyelectrolyte, can be used as a coagulant and flocculant aid in the water treatment process. For this purpose, tannin was coagulated and flocculated and thus the results obtained were compared with aluminium sulphate and synthetic polyelectrolyte AN913. The relation between supernatant turbidity and coagulant dosage obtained from the experiments done on the water samples which have different turbidity and pH with tannin, AN913 and aluminium sulphate was investigated according to pH level. The effect of stirring velocity and time were investigated for the optimum dosage. At the optimum experimental conditions the effects of various ions on turbidity was investigated and it was shown that Mg2+ and Fe3+ions were effective in the removal of turbidity by tannin. The relation between supernatant turbidity and flocculant aid dosage found from the experiments carried out with Aİ2(S04)3 - tannin and Aİ2(SC>4)3 - AN913 on synthetic water samples which have different turbidity was investigated. Economically, it was shown that Aİ2(S04)3 - tannin was 50% cheaper than Aİ2(SC>4)3 and was 25% cheaper than A12(S04)3 - AN913. For human health purposes A12(S04)3 - tannin usage was recommended when compared with Aİ2(S04)3 and AN913. And also the sludge specific resistance,time first floe and settling rate were investigated for three coagulant and for flocculant aid dosage at optimum dosage. The removal of phosphate from turbidity water with suspension and that from non- turbidity water was investigated. For low turbidity water, to remove turbidity from suspansions including phosphate, A12(S04)3 was shown to be effective. For high turbidity water the effects of A12(S04)3, A12(S04)3 - tannin and A12(S04)3 - AN913 were the same. To remove phosphate from turbidity water, it was seen that Aİ2(SC>4)3 was effective. However, when tannin and AN913 were used with A12(S04)3 respectively shown that those were better than the results obtained from single usage ofA]2(S04)3. xlvi