EXCESSIVE NITRATE DISCHARGED THROUGH AGRICULTURAL RUNOFF IS A LEADING CONTRIBUTOR TO THE BIGGEST GLOBAL WATER QUALITY PROBLEM - EUTROPHICATION. CURRENT TECHNOLOGIES FALL SHORT OF EFFECTIVE REMEDIATION. TO FILL THE TECHNOLOGY GAP, THIS PROJECT HAS AN OVERALL GOAL OF DEVELOPING A SOLAR-POWERED, CHEMICAL-FREE NITRATE REMOVAL (DENITRIFICATION) TECHNOLOGY THAT IS APPROPRIATE FOR AGRICULTURAL RUNOFF REMEDIATION. THE SPECIFIC OBJECTIVES INCLUDE: 1) IDENTIFY THE OPTIMAL DESIGN AND OPERATING PARAMETERS THAT CAN ACHIEVE EFFICIENT DENITRIFICATION IN THE PRESENCE OF DISSOLVED OXYGEN; AND 2) PINPOINT THE FUNCTIONAL ROLES OF DIFFERENT MICROBIAL SPECIES IN BIO-ELECTROCHEMICAL DENITRIFICATION. THE PROPOSED ACTIVITIES INCLUDE: 1) EVALUATE THE PERFORMANCE OF TWO DESIGNS ON LAB-MADE AND REAL-WORLD NITRATE-RICH WATER; AND 2) USE AN INNOVATIVE 'OMICS TECHNIQUE TO ANALYZE THE GENE TRANSCRIPTION OF BIO-ELECTROCHEMICAL DENITRIFICATION BIOFILMS UNDER A VARIETY OF LAB AND REAL-WORLD CONDITIONS. THE EXPECTED RESULTS INCLUDE: 1) VALIDATION OF THE FEASIBILITY OF BIO-ELECTROCHEMICAL DENITRIFICATION TREATING HIGH-VOLUME, COMPLEX REAL-WORLD WATER, AND 2) RNA-LEVEL KNOWLEDGE ON THE MOLECULAR MECHANISMS. THE RESULTS WILL HAVE SIGNIFICANCE IN INFORMING THE SCIENCE AND ENGINEERING RELATED TO MICROBIAL DENITRIFICATION, AND POTENTIALLY, LEAD TO THE DEVELOPMENT OF A TECHNOLOGY THAT CAN CONSIDERABLY MITIGATE THE NEGATIVE WATER QUALITY IMPACTS OF MODERN AGRICULTURE.