Water Resources Research Act Program

Principal Investigators: Dr. Pradeep K. Behera

Abstract: More than 1.2 billion people lack access to safe drinking water, 2.6 billion have limited or no sanitation, and millions of people die annually from diseases transmitted through unsafe water and human excreta (Shannon et. al., 2008). Drinking water sources are stressed due to climate change and population growth. Wastewater reuse is an alternative option for availability of freshwater, but centralized wastewater systems are not always feasible for developing countries. Moreover, 25% of the US population also depends on decentralized or onsite wastewater treatment (OWS) (Conn et al, 2006, Lowe and Siegrist, 2008). This percentage amounts to OWSs serving 22 million businesses and homes throughout the United States (Tomaras et al., 2009). OWSs treat and distribute wastewater from individual homes, small communities, and commercial buildings (Tomaras et al., 2007). Furthermore, centralized wastewater systems in different cities are under constant pressure for rapid urbanization. The goal for the water reuse is to capture water directly from non-traditional sources such as industrial or municipal wastewaters or from buildings and restore it to potable quality with options to recover resources to make it a sustainable and cost-effective technology (Shannon et. al., 2008). Wastewater contains a wide variety of contaminants and nutrient (e.g. emerging contaminants such as pharmaceuticals, nutrients such N & P etc) and pathogens. It also has a very high loading of organic matter which must be removed or transformed to harmless compounds by different widely adopted techniques such as activated sludge systems, trickling filter, membrane bioreactors (Shannon et. al., 2008). Membrane bioreactor holds wide promise for decentralized wastewater reuse due its small footprint, flexible design and automated operation with possibilities to produce high quality effluent suitable for unrestricted irrigation and other industrial applications in developing countries and improved sanitation for developing countries (Daiger et al., 2005; Yang et al., 2006; Bixio et al., 2006). Possible applications can be direct treatment of raw sewage in rapidly growing megacities such as Washington, DC with options for recovering valuable resources from sewage mainly clean water, nutrients (mainly N & P). Another growing application of MBR is as pretreatment for reverse osmosis (RO) followed by UV disinfection for direct or indirect potable reuse for megacities. Furthermore, traditional MBR processes is energy-intensive since aeration is necessary for the growth and activity of activated sludge. Furthermore, energy and nutrients in wastewater are lost as gases (e.g. carbon dioxide and nitrogen gas) in MBR treatment. Furthermore, another major challenge for employing MBR for next generation re-use systems is membrane fouling which leads to permanent flux losses caused by microbe-generated extracellular polymeric substances, most notably polysaccharides, proteins and natural organic matter (Yang et al., 2006; Kimura et al., 2005). Fouling of polymer membranes is influenced by membrane chemistry and morphology. An alternative MBR configuration, namely anaerobic MBR (AnMBR) can integrate anaerobic digestion treatment to produce methane rich biogas with membrane filtration. Furthermore, AnMBR can also facilitate nutrient recovery via subsequent precipitation in forms of struvite/vivianite minerals is possible.So, the objective of this research will be to develop an AnMBR systems for reusing gray water, rainwater and blackwater collected at DC and optimize the systems for water, nutrient and energy recovery. Two types of MBR challenges will be addressed: a) testing different antifouling membranes and its efficacy against membrane fouling for those three types of water & b) testing different innovative membrane cleaning techniques to minimize fouling. The recovery of water, nutrient and energy will be quantified and will be compared with other comparable systems. Though configurations have significant effects on the performance of AnMBR, this project for its limited scope will focus on submerged AnMBR systems at continuous stirred-tank reactor (CSTR) configuration only.