Potential for Enhanced Biological Phosphorus Removal in an activated sludge system for greywater

Abstract: As the world's population grows, concerns about water scarcity and rising pollution such as phosphorus and nitrogen have increased significantly. Greywater has been considered by researchers as an ideal alternative to fresh water for decades, and several projects have been implemented to treat and recycle it for various reuse purposes. Greywater, which makes up about 80% of household water consumption, is treated and reused by different treatment methods. One of the parameters that should be largely eliminated is phosphorus, the large amount of which causes many problems in human health and the environment, including eutrophication. Different treatment methods have been used to remove phosphorus. One of these most widely used methods is the Enhanced biological phosphorus removal (EBPR) method, which can remove high levels of phosphorus. This method has been implemented in the Oceanhamnen project for greywater in Helsingborg. In this master thesis, the potential for phosphorus removal by using the EBPR process was investigated. This was done by using one-year laboratory data provided by NSVA company along with two laboratory tests, P-release and 5-point titration experiments. In the early period of this master thesis, the concentration of sludge in aeration basin was significantly reduced and therefore re-inoculation process was performed by adding sludge from Öresundverket to accelerate the recovery operation. The experiments were done before and after the re-inoculation. Based on the results, despite the relatively high rate of phosphorus removal in the effluent, there was limited Bio-P activity in the system due to low sludge concentration as well as operational condition. Therefore, phosphorus removal might also occur by other mechanisms such as assimilation. Finally, by assuming that the sludge in Reco-Lab would be of the same quality of Öresundverket, the maximum potential for phosphorus removal was calculated and considered as maximum capacity of the EBPR system. However, this potential can only be considered for the Reco-Lab project with its specific condition as well as greywater characteristics.