scholarly journals Nitrate Removal Rate in a Continuous Column Denitrification Reactor Using Hydrogen Generated by Electrolysis with Carbon Anodes and Stainless Cathodes.

2001 ◽  
Vol 24 (7) ◽  
pp. 454-458
Author(s):  
Suhendar DADANG ◽  
Takuya KAWANISHI ◽  
Nobuaki SHIMIZU ◽  
Yoshishige HAYASHI
Keyword(s):  
Removal Rate ◽  
Nitrate Removal ◽  
Denitrification Reactor ◽  
Carbon Anodes

Nitrate removal rate in a continuous column denitrification reactor using hydrogen generated by electrolysis with carbon anodes and stainless cathodes

2002 ◽  
Vol 46 (11-12) ◽  
pp. 39-44 ◽  
Author(s):  
S. Dadang ◽  
T. Kawanishi ◽  
N. Shimizu ◽  
Y. Hayashi
Keyword(s):  
Activated Carbon ◽  
Removal Rate ◽  
Tap Water ◽  
Nitrate Removal ◽  
Fixed Bed ◽  
Reduction Rate ◽  
Potassium Nitrate ◽  
Nitrite Reduction ◽  
Flow Process ◽  
Carbon Anodes

An autotrophic continuous denitrification process, using hydrogen generated by electrolysis with activated carbon anodes, was experimentally demonstrated to be an effective nitrate removal process. Several fixed bed columns with polypropylene packing and honeycomb shaped activated carbon anodes and stainless rod cathodes were set in a thermostat chamber at 30°C, and potassium nitrate enriched tap water as influent was supplied at various flow rates and electric currents. Although the anode is in the same column where microbial biomass grows, sufficient nitrate removal was observed. For example, almost complete removal of nitrate and nitrite was observed at a hydraulic retention time (HRT) as short as 1.8 h. A model assuming successive denitrification reactions and plug-flow process, nitrate reduction rate = k1[NO3−] [H2], and nitrite reduction rate = k2 [NO2−]H2]1.5 was proposed. Calculated results with k1 = 1.3 mmol−1 h−1 and k2 = 3.3 mmol−1.5•h−1 agreed well with all the experimental results.

scholarly journals Denitrification-Potential Evaluation and Nitrate-Removal-Pathway Analysis of Aerobic Denitrifier Strain Marinobacter hydrocarbonoclasticus RAD-2

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1298 ◽  
Author(s):  
Dedong Kong ◽  
Wenbing Li ◽  
Yale Deng ◽  
Yunjie Ruan ◽  
Guangsuo Chen ◽  
...  
Keyword(s):  
Nitrate Removal ◽  
Aerobic Denitrification ◽  
Transcriptional Level ◽  
16S Rrna Sequence ◽  
Recirculating Aquaculture ◽  
N Removal ◽  
Denitrification Reactor ◽  
Potential Alternative ◽  
Marinobacter Hydrocarbonoclasticus

An aerobic denitrifier was isolated from a long-term poly (3-hydroxybutyrate-co-3-hydroxyvalerate) PHBV-supported denitrification reactor that operated under alternate aerobic/anoxic conditions. The strain was identified as Marinobacter hydrocarbonoclasticus RAD-2 based on 16S rRNA-sequence phylogenetic analysis. Morphology was observed by scanning electron microscopy (SEM), and phylogenetic characteristics were analyzed with the API 20NE test. Strain RAD-2 showed efficient aerobic denitrification ability when using NO3−-N or NO2−-N as its only nitrogen source, while heterotrophic nitrification was not detected. The average NO3−-N and NO2−-N removal rates were 6.47 mg/(L·h)and 6.32 mg/(L·h), respectively. Single-factor experiments indicated that a 5:10 C/N ratio, 25–40 °C temperature, and 100–150 rpm rotation speed were the optimal conditions for aerobic denitrification. Furthermore, the denitrifying gene napA had the highest expression on a transcriptional level, followed by the denitrifying genes nirS and nosZ. The norB gene was found to have significantly low expression during the experiment. Overall, great aerobic denitrification ability makes the RAD-2 strain a potential alternative in enhancing nitrate management for marine recirculating aquaculture system (RAS) practices.

Nitrate removal with lateral flow sulphur autotrophic denitrification reactor

2014 ◽  
Vol 35 (21) ◽  
pp. 2692-2697 ◽  
Author(s):  
Xiaomei Lv ◽  
Mingfei Shao ◽  
Ji Li ◽  
Chuanbo Xie
Keyword(s):  
Nitrate Removal ◽  
Lateral Flow ◽  
Autotrophic Denitrification ◽  
Denitrification Reactor

Polyacrylamide Wastewater Treatment in a Nested Biofilm Airlift Suspension Reactor

2013 ◽  
Vol 864-867 ◽  
pp. 1608-1611
Author(s):  
Zhong Chen Yu ◽  
Dong Ma ◽  
Song Wang ◽  
Xue Jiao Zhang
Keyword(s):  
Wastewater Treatment ◽  
Oil Recovery ◽  
Large Scale ◽  
Produced Water ◽  
Removal Rate ◽  
Nitrate Removal ◽  
Ammonia Nitrogen ◽  
Walnut Shell ◽  
Biofilm Thickness ◽  
Tertiary Oil Recovery

Polyacrylamide has been widely used in tertiary oil recovery. Oilfield produced water in a large scale contain polyacrylamide, leading to oilfield environment pollution. In this paper, the nested loops biofilm airlift suspension reactor was used in polyacrylamide wastewater treatment. In the reactor, wastewater can alternately flow through the hypoxic environment fixed light carriers and aerobic environment suspended walnut shell biological carriers, achieving simultaneous removal of organic matter and nitrogen. The influencing factors on the organic compound degradation and denitrification performance were studied. Biological and hydrodynamic model of nitrogen and carbon removal was established. Also, the biological phase structure of the carrier biofilm was observed. The results show that polyacrylamide degradation and ammonia nitrogen removal rate are around 30% and 95%, respectively when the experimental hydraulic retention time is 24h. Due to poor denitrification efficiency; nitrate removal rate is only 20%. The carrier biofilm thickness is appropriate, and filamentous bacteria occupy the dominant position.

scholarly journals Nitrogen removal from ammonium-contaminated groundwater using dropping nitrification–cotton-based denitrification reactor

2021 ◽  
Author(s):  
A. K. Maharjan ◽  
K. Mori ◽  
K. Nishida ◽  
T. Toyama
Keyword(s):  
Nitrogen Removal ◽  
Removal Rate ◽  
Denitrifying Bacteria ◽  
Electron Donors ◽  
Nitrifying Bacteria ◽  
Contaminated Groundwater ◽  
Total N ◽  
N Removal ◽  
Denitrification Reactor ◽  
Synthetic Groundwater

Abstract A novel dropping nitrification–cotton-based denitrification reactor was developed for total nitrogen (N) removal from ammonium (NH4+)-contaminated groundwater. The nitrogen removal ability of the reactor was evaluated for 91 days. A 1 m-long dropping nitrification unit was fed with synthetic groundwater containing 30 mg-NH4+-N/L at a flow rate of 2.16 L/d. The outlet of the dropping nitrification unit was connected to the cotton-based denitrification unit. The NH4+ present in the groundwater was completely oxidized (>90% nitrification efficiency) by nitrifying bacteria to nitrite (NO2–) and nitrate (NO3–) in the dropping nitrification unit. Subsequently, the generated NO2– and NO3– were denitrified (96%–98% denitrification efficiency) by denitrifying bacteria in the cotton-based denitrification unit under anoxic conditions. Organic carbons released from the cotton presumably acted as electron donors for heterotrophic denitrification. Nitrifying and denitrifying bacteria were colonized in higher abundance in the dropping nitrification and cotton-based denitrification units, respectively. The total N removal rate and efficiency of the dropping nitrification–cotton-based denitrification reactor for 91 days were 58.1–66.9 mg-N/d and 96%–98%, respectively. Therefore, the dropping nitrification–cotton-based denitrification reactor will be an efficient, sustainable, and promising option for total N removal from NH4+-contaminated groundwater.

scholarly journals Design and operation of submerged layer in bioretention for enhanced nitrate removal

2019 ◽  
Vol 68 (8) ◽  
pp. 744-756 ◽  
Author(s):  
Junyu Zhang ◽  
Rajendra Prasad Singh ◽  
Yunzhe Liu ◽  
Dafang Fu
Keyword(s):  
Activated Carbon ◽  
Removal Rate ◽  
Nitrate Removal ◽  
Yangtze River Delta ◽  
Lake Basin ◽  
Modified Activated Carbon ◽  
N Removal ◽  
Tai Lake ◽  
N 93 ◽  
Tai Lake Basin

Abstract Bioretention, initially designed for treating discontinuous runoff pollution, faces considerable challenges in its trade-off between the hydraulic retention time (HRT) and its treatment capacity. In this study, six enhanced submerged media together with four HRTs were designed for bioretention cells to treat the highly nitrogenous river water in Tai lake basin in Yangtze River delta, China. Results revealed that bioretention with activated carbon has the highest removal of nitrate (NO3−-N) (93–96%) compared with surfactant-modified activated carbon (SMAC), surfactant-modified zeolite (SMZ), zeolite, fly ash and ceramsite. Although the SMAC had the best absorption for NO3−-N and could desorb NO3−-N when its concentration was low in the submerged layer, the desorbed surfactant could inhibit the growth of denitrifying bacteria, which leads to low removal efficiency (49–66%). The dynamic balancing of NO3−-N desorption and denitrifying system restrain in the SMAC device was observed and explained. The best activated carbon-gravel proportion in the submerged layer was 1:1 (150 mm). Such design could ensure the stable and efficient NO3−-N removal rate (93–94%) under high inflow concentration (28.9 mg/L) and high hydraulic loading (8.2 cm/h).

scholarly journals Simultaneous removal of Fe3+ and nitrate in the autotrophic denitrification immobilized systems

2017 ◽  
Vol 18 (5) ◽  
pp. 1625-1634
Author(s):  
Jun feng Su ◽  
Ting ting Lian ◽  
Ting lin Huang ◽  
Dong hui Liang ◽  
Wen dong Wang
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Removal Rate ◽  
Nitrate Removal ◽  
Simultaneous Removal ◽  
Autotrophic Denitrification ◽  
Four Levels ◽  
Experimental Group

Abstract In this study, strain CC76, identified as Enterobacter sp., was tested for the reduction of Fe3+ and denitrification using immobilized pellets with strain CC76 as experimental group (IP) and immobilized pellets with strain CC76 and magnetite powder as experimental group (IPM) in the autotrophic denitrification immobilized systems (ADIS). Compared with IP, a higher nitrate removal rate was obtained with IPM by using three levels of influent Fe3+ (0, 5, and 10 mg/L), four levels of pH (5.0, 6.0, 7.0, and 8.0), and three levels of hydraulic retention time (HRT) (12, 14, and 16 h), respectively. Furthermore, response surface methodology (RSM) analysis demonstrated that the optimum removal ratios of nitrate of 87.21% (IP) and 96.27% (IPM) were observed under the following conditions: HRT of 12 h, pH of 7.0 and influent Fe3+ concentration of 5 mg/L (IP) and 1 mg/L (IPM).

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