Biological Greywater Treatment
Source separated sanitation is often thought of as creating a concentrated blackwater stream where energy in the form of biogas and nutrients can be recovered as well as a dilute greywater stream. Historically, blackwater has been the focus of research in the source separated sector but increased awareness around limited and vulnerable water supplies has caused us to reconsider greywater as an additional value stream. Greywater is dilute and therefore is comparatively easier to treat to a high-quality compared to blackwater and mixed wastewater. While much research exists on greywater treatment via membranes and constructed wetlands, there is still little understanding of greywater treatment with biological processes. Since greywater has different chemical properties than mixed wastewaters, it also poses challenges when using conventional treatment methods.
The pilot tests being completed at RecoLab and in the Testbed will compare two types of biological treatment to test for overall treatment efficacy and robustness of the systems. Activated sludge as it runs in RecoLab today and pilot scale Integrated Fixed Film Activated Sludge (IFAS) that use moving bed biofilm reactor (MBBR) carriers are being compared in parallel. The use of chemical precipitants and enhanced biological phosphorous removal can also be tested to further improve the quality of effluent greywater. The removal of organic carbon, nitrogen, phosphorus, and their various forms will be assessed and compared the proposed changes to the EU Urban Wastewater Treatment Directive as well as the EU directive on minimum requirements for water reuse to determine what water quality can be achieved and what types of reuse are feasible with these technologies.
The results of these studies will inform the design and expansion of source separated sanitation and greywater treatment systems, namely the next source separated project in Helsingborg; Östra Ramlösa.
For more information
Ashley Hall (doctoral student)
Sweden Water Research
ashley.hall@swrab.se
+46 70 832 54 12