Flexible hybrid membrane treatment systems for tailored nutrient management: A new paradigm in urban wastewater treatment D. Vuono a , J. Henkel a , J. Benecke a , T.Y. Cath a , T. Reid b , L. Johnson b , J.E. Drewes a,n a NSF Engineering Research Center ReNUWIt, Colorado School of Mines, Civil and Environmental Engineering,1500 Illinois St, Golden, CO 80401, USA b Aqua-Aerobic Systems Inc., 6306 North Alpine Road, Rockford, IL 61111, USA article info Article history: Received 15 February 2013 Received in revised form 11 June 2013 Accepted 15 June 2013 Available online 21 June 2013 Keywords: Sequencing batch reactor Membrane bioreactor Water reclamation Distributed wastewater treatment Tailored water reuse Integrated water resource management abstract The integration of onsite, decentralized, and satellite wastewater treatment systems into existing urban water infrastructure is an attractive option for recovering water and nutrients locally for multi-purpose reuse. To facilitate wastewater treatment and reuse, tailored to local needs, a hybrid membrane treatment process is proposed that couples sequencing batch reactors with a membrane bioreactor (SBR-MBR). In this study, we explored the flexibility and robustness of this hybrid membrane system at a demonstration-scale under real-world conditions by tightly managing and controlling operation conditions to produce effluent of different qualities for multipurpose reuse. Results suggest that an SBR-MBR treatment configuration is flexible, robust and resilient to changing operating conditions. The hybrid system was capable of producing different effluent qualities within 1 week of changing operating condition with no adverse effects on membrane performance. This work reinforces the need for a new paradigm of water reclamation and reuse and introduces a new treatment concept facilitating tailored nutrient management for a sustainable urban water infrastructure. & 2013 Elsevier B.V. All rights reserved. 1. Introduction Aging wastewater infrastructure, freshwater scarcity, population growth and urbanization, as well as climate change are drivers to advance the science and technology of recovering the resources present in domestic wastewater, a predominantly untapped resource harboring energy, nutrients, and fresh water [1,19,27]. As a dominant driver for water reuse, water scarcity is becoming increasingly prevalent on a global scale. Furthermore, more than half the Earth's human population lives in urban areas, creating increasing pressure and depletion of local water supplies [21]. In addition to water scarcity and urban population growth, decaying urban water infra- structure and inadequate end-of-pipe reuse strategies call into question whether the current paradigm of centralized wastewater treatment is capable of coping with the water supply challenges of the 21st century [10,23]. Thus, water planners and engineers must look beyond traditional methods of water supply (e.g., structural developments and inter-basin water transfers) and adopt an inte- grated, whole system approach to managing water assets [2]. These assets must include locally available reclaimed water as a strategic supply for balancing urban water use, meeting short-term needs, and improving long-term supply reliability [6]. Recently, onsite, satellite, and decentralized treatment systems (henceforth referred to collectively as distributed) have gained atten- tion for reclaiming used water in the urban environment [10]. Furthermore, advancements in membrane bioreactor technology have made the concept of sewer mining, or scalping, feasible for distributed installations across the urban area where demand for local reuse of water exists [6,8]. Source separation of black-water, urine, and grey- water has also been shown to be reliable and economically viable when implemented for new developments [27,29,7]; however, retro- fitting existing infrastructure for source-separated treatment might be economically impractical because the majority of the wastewater infrastructure is already in place. Nonetheless, retrofitting water infrastructure for new treatment approaches ultimately must be evaluated on a case-by-case basis, and planners and local commu- nities must weigh the benefits of infrastructure improvements. In order to prevent freshwater shortages within urban centers, these benefits may include water reclamation and reuse by integrating new treatment strategies into existing water infrastructure. While the advantages and disadvantages of centralized versus decentralized treatment systems have been discussed elsewhere [18], we target a specific niche of the urban water infrastructure aimed at facilitating distributed reuse within clustered housing developments and apartment complexes. Sequencing batch reactors (SBRs) and membrane bioreactors (MBRs) are uniquely suited for treating wastewater in decentralized settings. Unlike conventional activated sludge processes that employ several dedicated unit processes, SBRs are ideal because their operation is managed through Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/memsci Journal of Membrane Science 0376-7388/$ - see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.memsci.2013.06.021 n Corresponding author. Tel.: +1 3032733401. E-mail address: jdrewes@mines.edu (J.E. Drewes). Journal of Membrane Science 446 (2013) 34–41