Next Article in Journal
Using a Data Driven Approach to Predict Waves Generated by Gravity Driven Mass Flows
Previous Article in Journal
The Effect of Soil Iron on the Estimation of Soil Water Content Using Dielectric Sensors
Open AccessArticle

Ammonium-Nitrogen (NH4+-N) Removal from Groundwater by a Dropping Nitrification Reactor: Characterization of NH4+-N Transformation and Bacterial Community in the Reactor

1
Integrated Graduate School of Medicine, Engineering and Agricultural Sciences, University of Yamanashi, Yamanashi 400-8511, Japan
2
School of Allied Health Sciences, Kitasato University, Kanagawa 252-0373, Japan
3
Graduate Faculty of Interdisciplinary Research, University of Yamanashi, Yamanashi 400-8511, Japan
4
Department of Civil Engineering, Pulchowk Campus, Institute of Engineering, Tribhuvan University, Lalitpur 44700, Nepal
*
Author to whom correspondence should be addressed.
Water 2020, 12(2), 599; https://doi.org/10.3390/w12020599
Received: 21 November 2019 / Revised: 13 February 2020 / Accepted: 20 February 2020 / Published: 22 February 2020
(This article belongs to the Section Wastewater Treatment and Reuse)
A dropping nitrification reactor was proposed as a low-cost and energy-saving option for the removal of NH4+-N from contaminated groundwater. The objectives of this study were to investigate NH4+-N removal performance and the nitrogen removal pathway and to characterize the microbial communities in the reactor. Polyolefin sponge cubes (10 mm × 10 mm × 10 mm) were connected diagonally in a nylon thread to produce 1 m long dropping nitrification units. Synthetic groundwater containing 50 mg L−1 NH4+-N was added from the top of the hanging units at a flow rate of 4.32 L day−1 for 56 days. Nitrogen-oxidizing microorganisms in the reactor removed 50.8–68.7% of the NH4+-N in the groundwater, which was aerated with atmospheric oxygen as it flowed downwards through the sponge units. Nitrogen transformation and the functional bacteria contributing to it were stratified in the sponge units. Nitrosomonadales-like AOB predominated and transformed NH4+-N to NO2-N in the upper part of the reactor. Nitrospirales-like NOB predominated and transformed NO2-N to NO3-N in the lower part of the reactor. The dropping nitrification reactor could be a promising technology for oxidizing NH4+-N in groundwater and other similar contaminated wastewaters. View Full-Text
Keywords: NH4+-N removal; groundwater; dropping nitrification; ammonia-oxidizing bacteria; nitrite-oxidizing bacteria; polyolefin sponge NH4+-N removal; groundwater; dropping nitrification; ammonia-oxidizing bacteria; nitrite-oxidizing bacteria; polyolefin sponge
Show Figures

Graphical abstract

MDPI and ACS Style

Maharjan, A.K.; Kamei, T.; Amatya, I.M.; Mori, K.; Kazama, F.; Toyama, T. Ammonium-Nitrogen (NH4+-N) Removal from Groundwater by a Dropping Nitrification Reactor: Characterization of NH4+-N Transformation and Bacterial Community in the Reactor. Water 2020, 12, 599.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Search more from Scilit
 
Search
Back to TopTop