MANAGEMENT of PHOSPHORUS REMOVAL in MUNICIPAL WASTEWATER TREATMENT PLANTS

As a result of uncontrolled discharge of wastewaters containing high levels of phosphorus to the receiving bodies could create adverse effects on water quality. Therefore phosphorus should be eliminated prior to discharging into aquatic environment together with carbon and nitrogen to reduce eutrophication risk. Control of effluent phosphorus level by enhanced biological methods became a standard wastewater treatment application due to its high wastewater purification efficiency and its enhancing effect on overall biological treatment stages. In enhanced biological phosphorus removal (EBPR) processes, carbon, nitrogen and phosphorus could be removed simultaneously with higher efficiencies as compared to the conventional biological treatment methods. Another common method applied in wastewater treatment plants (WWTPs) for removal of phosphorus is chemical precipitation method in which aluminum and ferrous salts, lime were used as coagulants. Although these methods are not able to remove phosphorus completely from the theoretical aspect, significant phosphorus removal efficiencies could also be achieved. However chemical phosphorus removal methods could increase sludge production rate significantly in WWTPs. In this study, fundamental characteristics of EBPR were investigated in a large wastewater treatment plant by full-scale and laboratory scale methods. The process configuration in which investigations were carried out was very similar to 5-Stage Modified Bardenpho process. To obtain accurate results mass balances were established around biological treatment units performing detailed influent and effluent characterization. . In addition to the wastewater characterization, phosphorus content of both activated sludge and phosphorus accumulating organisms (PAOs) were examined under variable nutrient loading ratios and variable operational conditions.