Effect of different pH,temperatures and Fe2+ concentration on Sphaerotilus natans growth and clarity performance index

Summary An investigation was made of the effect of various environmental conditions of Sphaerotilus natans, an organism which causes sludge bulking, during the application of Fe²⁺ as inhibitor for bacterial growth. The ratio between non-settleable bacterial aggregates (turbidity) and bacterial plate count was regarded as representing the Clarity Performance Index (CPI).The results showed that ideal clarity was obtained at pH 6.5 and 30°C when 15 mg 1^-1 of Fe²⁺ applied. Under conditions, the percentage of inhibition of S. natans, the highest percentage of Fe²⁺ removal, and the CPI, compared to a control, were 87.50%, 29.58 and 0.962 respectively.