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Biocontrol Sci. 2018;23(3):139-143. doi: 10.4265/bio.23.139.

Behavior of Nitrate-Nitrogen and Nitrite-Nitrogen in Drinking Water.

Author information

1
Division of Biomedical Engineering, Research Institute, National Defense Medical College.
2
Department of Oral and Maxillofacial Surgery, National Defense Medical College.
3
Division of Environmental Medicine, Research Institute, National Defense Medical College.

Abstract

Nitrate-nitrogen (NO3-N) and nitrite-nitrogen (NO2-N) are constituents of the nitrogen cycle. NO3-N is toxic to humans, primarily due to its reduction to NO2-N. In Japan, NO3-N and NO2-N levels in tap water must not exceed 10 mg/L and only NO2-N alone not 0.04 mg/L, respectively. In this study, we verified the effect of microorganisms and ultraviolet (UV) to increase of NO2-N in water. First, all tested drinking-waters including tap water and commercial mineral water in PET bottles had < 2 mg/L NO3-N and undetectable levels (< 0.01 mg/L) of NO2-N. However, we found that NO2-N was generated in tap water left to stand at room temperature for several days, leading to increases in CF and TC counts and reduction of NO3-N. We also demonstrated that direct UV and sunlight irradiation of NO3-N-containing drinking water generated NO2-N in 1-2 h, with NO2-N reaching > 0.04 mg/mL by 4-6 h. On the other hand, NO3-N and NO2-N were undetectable in commercially purified water.

KEYWORDS:

Disinfectant; Microbicidal activity; Nitrate; Nitrite; Stability

PMID:
30249964
DOI:
10.4265/bio.23.139
[Indexed for MEDLINE]
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