This project was awarded through the "National Science Foundation (NSF) / National Natural Science Foundation of China (NSFC) Joint Research on Environmental Sustainability Challenges" opportunity. The Food-Energy-Water (FEW) Nexus is described as complex and inter-related global resource systems that rely on different ecosystem resources. FEW Nexus problems stem from the imbalance of different user activities, such as agricultural and water-use practices, that do not maintain the integrity of ecosystems that provide the resources for those activities. A more specific example of a FEW Nexus problem is the use of fertilizer for agriculture coupled with wastewater treatment practices. The current economic model of fertilizer utilization is unsustainable for multiple reasons. Ammonia fertilizer is produced through the energy-intensive and expensive Haber Bosch process, and phosphorus for fertilizer is mined at considerable cost. Energy and chemicals are further consumed for the removal of fertilizer-associated nutrients from wastewater from agricultural run-off to prevent environmental and public health problems. At the same time, pharmaceuticals in wastewater are contaminants of emerging concern (CECs), but conventional treatment plants are unable to adequately remove all nutrients and CECs. Consequently, nitrogen, phosphorus, and pharmaceuticals pollute surface, ground, and coastal waters when the inadequately treated wastewater treatment plant effluent is discharged to the environment. A new paradigm is needed to enable the transformations to i) economically and environmentally sustainable nutrient reuse and ii) a safer and more effective management strategy for CECs in wastewater. Urine streams are rich in nutrients and have high concentrations of pharmaceuticals. However, urine is immediately diluted over 100 times by flushing and subsequent mixing with other wastewater streams, making it difficult to separate CECs and nutrient pollutants. A more rational approach would be to take advantage of the high concentrations of the nutrients and contaminants in undiluted urine by carrying out source-separation for decentralized resource recovery and pharmaceutical degradation, rather than treating the diluted urine at centralized wastewater treatment plants . This international collaborative project between the U.S. institutions of Columbia University and Vanderbilt University, and the Harbin Institute of Technology in China proposes an integrated treatment approach for source-separated urine, comprising i) ammonia recovery, ii) phosphate extraction, and iii) pharmaceutical degradation, to simultaneously achieve sustainable on-site nutrient recycling and contaminant elimination. Advancing fundamental knowledge on decentralized technologies for nutrient recovery and reuse and CEC elimination in urine source-separation and management will yield transformative impacts to enable the evolution of current wastewater management approaches to a more sustainable "resource recovery" approach.
The goals of this project are to enhance fundamental knowledge of the principal phenomena governing nitrogen and phosphorous recovery and pharmaceutical degradation in source-separated urine, and to assess the high-level impacts of implementing decentralized wastewater management. Specific objectives are: 1) to advance fundamental understanding of ammonia and water vapor transport across hydrophobic microporous membranes, 2) elucidate the fouling mechanisms during ammonia recovery from hydrolyzed source-separated urine, and formulate appropriate fouling control strategies, 3) investigate the degradation of model pharmaceutical compounds by advanced oxidation processes, 4) evaluate the fate of model pharmaceutical compounds and heavy metals in phosphate recovery by induced precipitation, and 5) assess the national-level environmental and public health impacts of large-scale implementation of urine source-separation in the U.S. and China. This study will investigate nutrient recovery and pharmaceutical degradation of diverted urine to elucidate the common denominators influencing the different phenomena of, and identify the overall achievable performance of, ammonia separation, phosphate extraction, and pharmaceutical degradation through integrated research. The project will advance fundamental knowledge on the benefits and costs of implementing urine source-separation and decentralized treatment in the U.S. and China. Critical insights from the specific research tasks have far-reaching impacts on individual topics, including i) enhanced transport theory of vapor in micropores, ii) improving the understanding of fouling and fouling mitigation in membrane distillation, iii) identification of principal factors governing advanced oxidation processes for pharmaceuticals, and iv) elucidation of contaminant fate in phosphate precipitation. This collaborative project will integrate education and research to train and prepare graduate, undergraduate, and high school students in STEM. The researchers will engage in activities including: (i) recruitment of under-represented groups, (ii) development of nutrient and microcontaminant modules for K-12 education and public outreach, (iii) providing undergraduate research opportunities through structured programs, and (iv) enhancing undergraduate and graduate education by integrating scientific concepts and technical principles of the research current courses.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
