[Phosphorus as a limiting nutrient in drinking water biological treatment].

Bacterial Growth Potential (BGP) method was used to investigate the limiting effect of phosphorus in the biological process for drinking water treatment in a water plant in Huai River basin. BGP was increased by 54% when 50 micrograms.L-1 KH2PO4-P was added to the raw water, while addition of other inorganic nutrients had no significant difference from the addition of phosphorus. The effect of addition of 20 mg.L-1 C6H12O6 to raw water was not so strong as that of 50 micrograms.L-1 KH2PO4-P. The CODMn removal rate of the biological filter was 7.5 percentiles higher than the control one and carbon was the main limiting nutrient in its effluent when phosphorus was added to the raw water, while phosphorus was the main limiting nutrient in the effluent of the control filter. These results suggest that phosphorus was a limiting nutrient and had a stronger limiting effect than carbon on the biological process in this plant thus the removal efficiency of the organic matters could be increased by adding phosphorus to the influent.