Non Technical Summary
Over the past decade, the demand for water reuse has been increasing due to growing populations, water scarcity and the impacts of climate change. The agricultural industry is one of the major consumers of fresh water. In addition to water for irrigation, significant water use is exhibited in the processing of agricultural products. For example, the demand for fresh and fresh-cut (minimally processed) fruits and vegetables has risen considerably. To reduce the possibility of pathogen contamination and improve product safety, fresh produce providers have long used chlorine disinfection in post-harvest processing. While chlorine is an effective disinfection agent against a broad range of microorganisms, high levels of organic compounds from soil and vegetable debris lead to excessive and varying chlorine demands, which can deteriorate wash water quality and safety, and frustrate efforts to implement water reuse technologies.The problem of low wash water quality is underscored by two national challenges.First, severe freshwater scarcityin the nation's agricultural regions has driven ongoing efforts to adopt sustainable water practices through water reuse. The fresh produce industry is among the highest agricultural users of water, yet low wash water quality diminishes the ability for manufacturers to safely reuse wash water more than a few times.Second, cross-contamination by pathogenscontinues to pose an outsized risk to the multi-billion-dollar fresh and fresh-cut produce industry. Low wash water quality not only enhances the likelihood of this devastating food safety risk, but also complicates the mitigation of pathogens on fresh produce due to dynamic and sometimes unpredictable chlorine demands in post-harvest processing.This project develops and evaluates a new biocatalyst-based technology process for achieving low-cost water reuse with particular emphasis in fresh and fresh-cut produce operations. Building on promising preliminary results, the proposed technology process leverages engineered biocatalytic composites to safely and rapidly reduce the levels of dissolved organic and inorganic compounds in wash water under very low temperatures, without contributing solids or secondary wastes to the wash water. The proposed technology therefore substantially enhances the energy efficiency and robustness of an integrated filtration and membrane-based water treatment unit to provide high quality recycled water that substantially mitigates the risk of pathogens. It is anticipated that this proposed technology process will substantially reduce the cost barrier for adopting water reuse practices across a range of agricultural sectors, thereby contributing to increased food safety and furthering sustainable water reuse processes across our nation's agricultural industry.

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
111	0210	1100	100%

Knowledge Area
111 - Conservation and Efficient Use of Water;

Subject Of Investigation
0210 - Water resources;

Field Of Science
1100 - Bacteriology;

Goals / Objectives
This project develops and evaluates a new biocatalyst-based technology process for achieving low-cost water reuse with particular emphasis in fresh and fresh-cut produce operations. Building on promising preliminary results, the proposed technology process leverages engineered biocatalytic composites to safely and rapidly reduce the levels of dissolved organic and inorganic compounds in wash water under very low temperatures, without contributing solids or secondary wastes to the wash water. The proposed technology therefore substantially enhances the energy efficiency and robustness of an integrated filtration and membrane-based water treatment unit to provide high quality recycled water that substantially mitigates the risk of pathogens. It is anticipated that this proposed technology process will substantially reduce the cost barrier for adopting water reuse practices across a range of agricultural sectors, thereby contributing to increased food safety and furthering sustainable water reuse processes across our nation's agricultural industry. The specific tasks in this project include:Task A: Conduct a series of directed evolution chemostat studies to acclimate a monoculture for efficient low-temperature degradation of dissolved organic compounds.Task B: Establish low-temperature degradation rates using the acclimated monoculture and compare with an analogous biocatalyst using synthetic and actual water.Task C: Construct and operate a bench-scale prototype of the serial-treatment process and establish baseline parameters in several configurations.Task D: Conduct a preliminary technoeconomic analysis to determine the economic viability of the proposed technology in the current technology landscape.

Project Methods
The methods in the proposed project correspond to the following four (4) tasks:• Task A: Conduct a series of directed evolution chemostat studies to acclimate a monoculture for efficient low-temperature degradation of dissolved organic compounds.• Task B: Establish low-temperature degradation rates using the acclimated monoculture and compare with an analogous biocatalyst using synthetic and actual water.• Task C: Construct and operate a bench-scale prototype of the serial-treatment process and establish baseline parameters in several configurations.• Task D: Conduct a preliminary technoeconomic analysis to determine the economic viability of the proposed technology in the current technology landscape. As part of Task A, ahigh-rate biological organics degradation system will be developed by acclimatinga mesophilic monoculture in a high-throughput directed evolution format.Directed evolution is a powerful technique to isolate natural genetic variants (non-GMO) with desired characteristics from a large or mixed population using selection strategies. In Task B, after repeated rounds of selection and enrichment provide a psychrotolerant mesophilic axenic culture, a batch kinetics study will evaluate the specific rate of dissolved organic compound degradation. In Task C,we will evaluate alternative sequential treatment processes using the biocatalysts to remove dissolved organic compounds to reduce fouling and increase recovery efficiency. Finally, in Task D,we will develop economic predictions based on key cost parameters (e.g., required hydraulic retention times, packing densities, equipment sizes, maintenance frequency) for both a retrofit to a flume washing process as well as a potential spray-washing reuse process.