Decentralized wastewater treatment has thus far been applied mostly for remote dwellings and developments, recently considerable attention is going towards its application in urban settings. Whereas existing cities in developed countries typically have well developed sewer systems, introducing building level treatment decreases the overall potable water demand as well as the wastewater flow to be transported towards wastewater treatment plants. Besides avoiding additional infrastructure for growing populations, decentralized systems enable faster evolution of water technology as smaller units can move faster through developmental generations. This presentation gives a brief overview on the drivers for decentralized wastewater treatment within an urban context, and then highlight where biological systems will play a pivotal role. In a recent study, parallel bioreactors were operated aiming at treating greywater at building level. Using first a synthetic greywater, the two most popular approaches were compared: moving bed biofilm reactors (MBBR) and membrane bioreactors (MBR). For the latter, we applied first polymeric membranes to later on switch to ceramic (SiC) membranes. All systems achieved adequate removal of COD and can deal with the presence of detergents in the wastewater. However, the MBR outperformed the MBBR in terms of nitrification efficiency as well as for overall COD removal. Particularly the ceramic MBR, operated at a low LMH of 9, showed high performance over &gt;6 months with minimal maintenance requirements particularly in terms of membrane fouling. For all systems, we subsequently applied post disinfections either via UV (standard approach) or electrochemical disinfection. The latter is attractive for maintaining some oxidants in the treated water avoiding regrowth in piping systems, as well as dealing well with the presence of residual solids particularly in case of the MBBR. Based on the results, MBR were chosen as technology to further develop and 2 systems were deployed at a recreational area to continuously treat greywater.

Decentralized greywater treatment within an urban environment enables effective water reuse

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.