Journal of Water and Environment Technology
Online ISSN : 1348-2165
ISSN-L : 1348-2165
Original Articles
Ammonium Removal from Alkaline Groundwater Using A Dropping Nitrification Unit with Sponge or Biofringe Material
Amit Kumar MaharjanTatsuru KameiKazuhiro MoriKei NishidaTadashi Toyama
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Supplementary material

2021 Volume 19 Issue 6 Pages 302-315


Ammonium (NH4+) contamination makes groundwater undrinkable. The dropping nitrification unit, a simple and low-cost biological unit, has been found to be effective for NH4+-removal from contaminated groundwater at a near-neutral pH. However, the pH of groundwater varies widely and is highly alkaline (pH 8.7−10) in some areas of the world, which could negatively affect the biological nitrification process. The objectives of this study were to investigate the NH4+-removal from alkaline groundwater using dropping nitrification units with sponge or biofringe material, compare their removal efficiencies, and characterize the effect of alkaline groundwater on the growth and activity of nitrifying bacteria. Synthetic alkaline groundwater (50 mg-NH4+-N L−1; pH 9.4 ± 0.1) was dropped from the top of 1-m long hanging units at 3 mL min−1 for 56 days. The NH4+-removal efficiency of sponge units (> 88%) was significantly higher than that of biofringe units (56−89%). The abundance of amoA gene of ammonia-oxidizing bacteria increased significantly over 56 days and was significantly higher in sponge units than in biofringe units, resulting in higher NH4+-removal in sponge units than that in biofringe units. This study demonstrated that dropping nitrification units can be used effectively for NH4+-removal from groundwater having a neutral to alkaline pH.

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© 2021 Japan Society on Water Environment

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