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Nitrate Removal via a Formate Radical-Induced Photochemical Process
Gongde Chen1, Sergei Hanukovich1, Michelle Chebeir1
1Department of Chemical and Environmental Engineering , University of California at Riverside , Riverside , California 92521 , United States.
Environmental Science & Technology
|December 1, 2018
Summary
This study introduces a novel photochemical denitrification process using UV light and formate to remove excess nitrate and other dissolved nitrogen compounds from water. The method shows high efficiency for decentralized water treatment, balancing aquatic nitrogen cycles.
Area of Science:
- Environmental Chemistry
- Photochemistry
- Water Treatment Technologies
Background:
- Excess nitrate in aquatic systems disrupts the nitrogen cycle.
- Current denitrification methods face challenges in efficiency and application scope.
Purpose of the Study:
- To investigate a novel photochemical denitrification process using nitrate photolysis and formate.
- To optimize conditions for simultaneous removal of dissolved nitrogen and organic carbon.
Main Methods:
- Utilized UV light irradiation to induce nitrate photolysis, generating reactive radicals.
- Investigated the role of formate oxidation by radicals to produce a highly reductive formate radical.
- Analyzed the reduction of nitrogen intermediates by the formate radical to gaseous nitrogen products.
Main Results:
- Photochemical oxidation of formate generated a formate radical (CO2•−) that reduced nitrogen intermediates to N2O and N2.
- Degradation kinetics were governed by nitrate and nitrite photolysis rates.
- Optimal formate-to-nitrate stoichiometry determined as 3.1 ± 0.2 at neutral pH for complete removal.
- Process showed negligible impact from dissolved organic matter and high efficiency in synthetic groundwater.
Conclusions:
- Developed a promising photochemical denitrification technology for decentralized water treatment.
- The process effectively removes nitrate, nitrite, and ammonia, alongside organic carbon.
- Offers a sustainable solution for abating nitrate in local water resources and promoting water reuse.
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