Effect of Bicarbonate on the Performance of Hydrogen-based Denitrification at Different Hydraulic Retention Times

Rujakom, Suphatchai; Shinoda, Kenta; Singhopon, Tippawan; Nakano, Mai; Kamei, Takeshi; Kazama, Futaba

doi:10.2521/jswtb.56.33

Cited by 5 publications

(24 citation statements)

References 36 publications

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“…Although NO 2 − -N concentrations in the D1 effluent were found to be close to 0 mg-N/L (Figure 4b), the average was 2.1 ± 2.9 mg-N/L and the NO 2 − -N concentrations exceeded the limit in 11 out of the 21 samples taken. To avoid undesirable NO 2 − -N accumulation in the system and enhance the complete denitrification, the abundant addition of HCO 3 − (more than 3000 mg/L) could be a potential option [25].…”

Section: Variations In Nitrogen Concentrationsmentioning

confidence: 99%

“…In the present study, the water temperature inside the reactor stayed within this range for HD performance without temperature control. The pH during HD usually increases because the process produces OH − ions as a byproduct [25]. The average pH of the influent and the effluents of D1 and D2 were 7.9 ± 0.1, 9.0 ± 0.2, and 7.9 ± 0.2, respectively.…”

Section: Variations In Nitrogen Concentrationsmentioning

confidence: 99%

“…Biological denitrification processes are broadly classified into two groups: heterotrophic and autotrophic denitrification, and the former has been conventionally studied for NO 3 − -N removal. The addition of organic carbon entailed in the activation of heterotrophic denitrification raises concerns regarding the increased risk of secondary pollution associated with elevated levels of total organic carbon [21,[23][24][25].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, hydrogenotrophic denitrification (HD), which is a type of autotrophic denitrification, has drawn much attention as a promising technology for nitrate removal from groundwater [19,21,[23][24][25][26][27][28][29][30][31][32][33][34][35][36] because it offers certain advantages over heterotrophic denitrification systems. First, biomass generation can be reduced, thereby reducing clogging and the cost of post-treatment [33].…”

Section: Introductionmentioning

confidence: 99%

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Hydrogenotrophic Denitrification of Groundwater Using a Simplified Reactor for Drinking Water: A Case Study in the Kathmandu Valley, Nepal

Shinoda

Maharjan

et al. 2021

Water

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High nitrate-nitrogen (NO3−–N) content is a typical feature of groundwater, which is the primary water source in the Kathmandu Valley, Nepal. Considering the Kathmandu Valley’s current problem of water scarcity, a user-friendly system for removing NO3−–N from groundwater is promptly desired. In this study, a simplified hydrogenotrophic denitrification (HD) reactor was developed for the Kathmandu Valley, and its effectiveness was evaluated by its ability to treat raw groundwater. The reactor operated for 157 days and showed stability and robustness. It had an average nitrogen removal efficiency of 80.9 ± 16.1%, and its nitrogen loading rate and nitrogen removal rate varied from 23.8 to 92.3 g–N/(m3∙d) and from 18.3 to 73.7 g–N/(m3∙d), respectively. Compared to previous HD reactors, this simplified HD reactor is a more user-friendly option for the Kathmandu Valley, as most of the materials used for the reactor were locally available and require less maintenance. The reactor is recommended for groundwater treatment at the household level. It has a current treatment capacity of 40 L/d, which can fulfill the daily requirements for drinking and cooking water in a household with 4–5 people.

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Section: Variations In Nitrogen Concentrationsmentioning

confidence: 99%

Section: Variations In Nitrogen Concentrationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Hydrogenotrophic Denitrification of Groundwater Using a Simplified Reactor for Drinking Water: A Case Study in the Kathmandu Valley, Nepal

Shinoda

Maharjan

et al. 2021

Water

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“…The amplified metagenomic sequences were obtained using the MiSeq platform. The raw sequence data were then taxonomically classified using QIIME software version 1.9.0 to obtain the operational taxonomic units (OTUs), which were then clustered at 97% similarity and the relative bacterial abundance [27]. The bacterial abundances observed under different operation conditions were presented in a heatmap, which was created using R software version 4.0.2 with the Heatplus (version 2.30.0) and Vegan (version 2.5.6) packages.…”

Section: Bacterial Community Analysismentioning

confidence: 99%

Factors Affecting the Simultaneous Removal of Nitrate and Reactive Black 5 Dye via Hydrogen-Based Denitrification

Singhopon

Shinoda

Rujakom

et al. 2021

Water

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Textile wastewater (TW) contains toxic pollutants that pose both environmental and human health risks. Reportedly, some of these pollutants, including NO3-, NO2- and reactive black 5 (RB-5) dye, can be removed via hydrogen-based denitrification (HD); however, it is still unclear how different factors affect their simultaneous removal. This study aimed to investigate the effect of H2 flow rate, the sparging cycle of air and H2, and initial dye concentration on the TW treatment process. Thus, two reactors, an anaerobic HD reactor and a combined aerobic/anaerobic HD reactor, were used to investigate the treatment performance. The results obtained that increasing the H2 flow rate in the anaerobic HD reactor increased nitrogen removal and decolorization removal rates. Further, increasing the time for anaerobic treatment significantly enhanced the pollutant removal rate in the combined reactor. Furthermore, an increase in initial dye concentration resulted in lower nitrogen removal rates. Additionally, some of the dye was decolorized during the HD process via bacterial degradation, and increasing the initial dye concentration resulted in a decrease in the decolorization rate. Bacterial communities, including Xanthomonadaceae, Rhodocyclaceae, and Thauera spp., are presented as the microbial species that play a key role in the mechanisms related to nitrogen removal and RB-5 decolorization under both HD conditions. However, both reactors showed similar treatment efficiencies; hence, based on these results, the use of a combined aerobic/anaerobic HD system should be used to reduce organic/inorganic pollutant contents in real textile wastewater before discharging is recommended.

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Efficacy of a Fine Bubble Diffuser in Enhancing Attached Biofilm Hydrogenotrophic Denitrification Reactor Performance

Kamei

Narushima

Kodera

et al. 2023

Water Air Soil Pollut

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The efficacy of a fine bubble (FB) diffuser in enhancing the performance of an attached biofilm hydrogenotrophic denitrification (HD) reactor was evaluated. HD reactors equipped with an FB diffuser (FB reactor) and an air stone (AS) diffuser that produced ordinary bubbles (AS reactor) were operated in parallel at different hydraulic retention times (HRTs) in a synthetic groundwater treatment experiment. A reduction in H2 consumption of approximately 77% was achieved using the FB diffuser to reach a gas-liquid mass transfer coefficient similar to that of the AS diffuser. The high gas dissolution efficiency of the FB diffuser resulted in an effective nitrogen removal rate (NRR) enhancement, requiring less H2 supply. The highest value of NRR at 53.0±9.8 g-N/m3/d was obtained in the FB reactor at a minimum HRT of 3 h, which was two-fold higher than the corresponding value from the AS reactor. The FB reactor also had the lowest requirement of H2 for denitrification reaching 0.1 m3-H2/g-N in this condition, which was ten-fold lower than that in the AS reactor. Furthermore, the suspended sludge concentration in the FB reactor was lower than that in the AS reactor, indicating that the application of the FB diffuser can minimize excess suspended sludge accumulation inside the HD reactor. Microbial community analysis showed the predominance of Thauera spp. reaching a relative abundance of 15.7–27.3% in the FB reactor, suggesting a contribution to the HD. This finding can provide insight into the application of the FB diffuser for optimizing nitrate-contaminated groundwater treatment technology by HD.

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Effect of Bicarbonate on the Performance of Hydrogen-based Denitrification at Different Hydraulic Retention Times

Cited by 5 publications

References 36 publications

Hydrogenotrophic Denitrification of Groundwater Using a Simplified Reactor for Drinking Water: A Case Study in the Kathmandu Valley, Nepal

Hydrogenotrophic Denitrification of Groundwater Using a Simplified Reactor for Drinking Water: A Case Study in the Kathmandu Valley, Nepal

Factors Affecting the Simultaneous Removal of Nitrate and Reactive Black 5 Dye via Hydrogen-Based Denitrification

Efficacy of a Fine Bubble Diffuser in Enhancing Attached Biofilm Hydrogenotrophic Denitrification Reactor Performance

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