Fate and Removal of Phosphorus in a Municipal Wastewater Treatment Plant

Nutrient including nitrogen and phosphorus released from agricultural and other anthropogenic activities can be easily transported into aquatic ecosystems. Excessive input of nutrients may cause a variety of environmental issues such as the proliferation of toxic algal blooms (eutrophication), dissolved oxygen decrease, impairment of the fish population, biodiversity loss, and water usability reduction for drinking, agriculture, and industry. Compared to nitrogen, phosphorus is the limiting nutrient in most surface water systems and thus is of particular concern. The total phosphorus concentration in the surface water is suggested as 10-40 μg/L by the USEPA. In order to investigate phosphorus removal in wastewater treatment processes, a better understanding of the fate of phosphorus in different treatment units is essential. In this study, the fate of phosphorus in a municipal wastewater treatment plant (Town Branch Wastewater Treatment Plant) located in Lexington, Kentucky, was investigated. The results show that approximately 30% of phosphorus was removed by the entire wastewater treatment process in which the primary clarifier was the main subunit attributed to phosphorus removal. Little removal was observed in the final clarifier while negative removal was observed in the aeration basin. A decreasing average removal was also observed after each year but not after each month. The correlation analysis showed that the total phosphorus removal was positively correlated to the phosphorus load.