Release of geosmin by Anabaena circinalis following treatment with aluminium sulphate

Taste and odour due to algae are not generally removed during conventional water treatment and can sometimes be increased during the treatment process owing to cell lysis. Some reasons for this have been documented in the literature but there appears to be contradictory evidence regarding the effect of flocculation. In this study the effect of aluminium sulphate on cultured cells of Anabaena circinalis was evaluated at concentrations and conditions that would occur in a water treatment plant. Aluminium sulphate did not appear to cause lysis of cells of cultured Anabaena circinalis nor increase the amount of geosmin in the water. Flocculation under laboratory conditions, which simulated operating water treatment plants, resulted in removal of cells in a healthy state, with no additional release of geosmin.