INFEWS/T3: Closing the Loop: An Integrated, Tunable, and Sustainable Management System for Improved Energy, Nutrient, and Water Recovery from Biowastes

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Phosphorus is an element that, along with nitrogen and potassium, has enabled large increases in food production in the U.S. and globally. Phosphorus is mined from natural deposits, but these deposits are diminishing. Contemporary reports indicate that there is a pending phosphorus crisis, as global supplies dwindle and demand for food increases. Currently, the utilization of phosphorus for fertilizer is energy intensive and expensive. Phosphorus supply is limited, and its recovery from food and other wastes and water bodies is virtually non-existent. Traditionally, agricultural production has been optimized with little or no consideration of the losses of phosphorus beyond its use in producing crops. This practice leads to large energy needs for fertilizer production and for treatment of phosphorus waste in agricultural run-off, and food and animal wastes. The other side to this problem is that some phosphorus applied to agricultural fields is lost to lakes and rivers causing considerable environmental damage. These phosphorus issues significantly influence our food, energy, and water (FEW) systems. Two key approaches to achieve sustainable phosphorus management are agriculture fertilization systems that more efficiently use phosphorous for plant growth and systems that recover phosphorus from food and animal wastes and from biowastes in contaminated water. Unfortunately, we do not have suitable recovery systems due to technological limitations and economic and infrastructure constraints. This project aims to develop an integrated and sustainable management structure that can simultaneously address the major technical challenges in biowaste management and agriculture fertilization systems. This management structure will enable recovery of phosphorous, energy, and water, thus increasing resource use efficiency and providing a new source of phosphorus for agricultural food production. This project integrates novel technologies in multiple fields, including hydrothermal treatment, anaerobic digestion, membrane distillation, struvite production, and magnetic nanoparticle separation to collect and recycle more phosphorous as struvite. The various systems are being analyzed and optimized to fit a number of waste-stream settings in order to reduce overall energy input. This approach offers many benefits such as reduced waste volume, decontamination of pathogens, as well as the production of clean water, energy, and slow release fertilizers. The method is also sufficiently flexible to accommodate different biowaste feedstocks and tunable to produce different recycled nutrient, energy, and water products, sustainable with low resource and energy input, and scalable to suit different levels of management needs. This system is being developed and tested at bench scale, up-scaled to prototype level, and optimized through systems modeling. Crop utilization efficiency and soil retention of the produced struvite fertilizers are being evaluated by growing corn, soybean, and wheat in both potted greenhouse experiments and in field trials. In order to identify the costs and benefits of these combined waste and fertilization management techniques, the researchers are performing a life cycle assessment (LCA) of the phosphorous removed from the various waste streams and recycled for agricultural applications. This analysis includes an evaluation of the phosphorous recovery and recycling efficiency, examination of the overall energy balance of the systems, a cost estimation of the systems, and an environmental assessment of the system. The project is combining student and postdoctoral researcher training with undergraduate education and promoting STEM research in underrepresented groups and K-12 education on integrated approaches to promote sustainable communities. Finally, the project is promoting awareness, knowledge, and practice of "Sustainability at the FEW Nexus" to a broad range of audiences including both academic and public sectors.