Effect of Chemical Addition on Biological Phosphorus Removal System

Biological phosphorus removal which is assisted by chemical dose has potential impact on phosphorus accumulating organism.The simultaneous phosphorus removal was done to treat domestic wastewater in the college by adding ferrous sulphate.Considering confused constituent of phosphorus precipitation which interferes with biological phosphorus analysis,chemically pure ferric phosphate and ferric hydroxide were chosen to represent phosphorus precipitation.Phosphorus removal by PAO was calculated according to potassium and mol ratio of K/P in order to evaluate the effect of chemical dose on biological phosphorus removal.Results showed that continuous addition of FeSO 4 resulted in decrease of phosphorus release and adsorption by PAO.Ferric phosphate of 0.075 mmol/L stimulated the phosphorus release and adsorption of PAO by 25%,while ferric phosphate of 0.15 mmol/L had inhibition on phosphorus release.Phosphorus release and initial adsorption by PAO were inhibited by ferric hydroxide.There was interaction between biological sludge and chemical sludge.