Release Reductions of Gaseous Ammonia and Nitrogen Oxides from Electrochemical Treatment of Swine Wastewater

Kuo-Lin Huang,Jen-Hsiung Tsai,Chou-Ching Liu,Shui-Jen Chen,Chen-Yao Ma,Ting-Chun Lin,Chia-Wei Lee

doi:10.4209/aaqr.2019.09.0486

Abstract

ABSTRACT This study investigates the release of NH3 and nitrogen oxides (NOx) from wastewater into the air in relation to the variations in NH3-N, NO2–-N, NO3–-N, and chemical oxygen demand (COD) concentrations in the swine wastewater with/without electrolysis using boron-doped diamond (BDD), PbO2, and graphite anodes. The NH3 concentration in the air right above the swine wastewater without electrolysis increased over time and this increase was greater when the wastewater NH3-N concentration was higher. Electrolysis could reduce the release of NH3 from swine wastewater into the air. The NO concentration in the air was greater for the wastewater without electrolysis than for that with electrolysis but an opposite trend was observed for NO2, although the corresponding NOx concentrations for the wastewater with and without electrolysis were similar. Roughly, the air NH3, NO, NO2, or NOx concentrations for using the different anodes in wastewater electrolysis followed the order Nb/BDD >> graphite/BDD > graphite > graphite/PbO2 ≈ Ti/PbO2. Although the BDD and graphite anodes showed less formation of nitrite or nitrate than the PbO2 anodes, the graphite/BDD and graphite anodes had worse performance in NH3-N or COD electro-degradation than the other tested ones. When the initial concentration of NH3-N or COD was higher, its specific energy consumption in electrolysis was lower.

Highlights

Pig farming including intensive or large-scale raising and breeding operations is still necessary to meet the increasing pork demand in several countries (Osada et al, 2017; Song et al, 2017)
This study investigates the release of NH3 and nitrogen oxides (NOx) from wastewater into the air in relation to the variations in NH3-N, NO2–-N, NO3–-N, and chemical oxygen demand (COD) concentrations in the swine wastewater with/without electrolysis using boron-doped diamond (BDD), PbO2, and graphite anodes
The NO concentration in the air was greater for the wastewater without electrolysis than for that with electrolysis but an opposite trend was observed for NO2, the corresponding NOx concentrations for the wastewater with and without electrolysis were similar

Summary

Introduction

Pig farming including intensive or large-scale raising and breeding operations is still necessary to meet the increasing pork demand in several countries (Osada et al, 2017; Song et al, 2017). Despite the recent spread of African swine fever to new areas or countries, China, the United States and the European Union held the first, second, and third positions, respectively, for the global pork production in 2018 (Deblitz et al, 2018) This phenomenon causes the generation of considerable amounts of swine wastewater which needs to be well treated before discharge for the prevention of surface and underground water pollution, because several types of pollutants including high levels of organic and nitrogen compounds might be present in swine wastewater, which are Another great environmental concern for pig farming is the emissions of ammonia (NH3) and greenhouse gases (e.g., CH4, CO2, and N2O) from the wastewater in purification facilities or the slurry in storages at pig farms prior to land application (Viguria et al, 2015; Osada et al, 2017). NH3 and NOx are two of most important pollutants that need more intensive monitoring for the air

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Conclusion