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 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 Biological Removal of Nitrates from Groundwater Resources in Saudi Arabia

2020 ◽  
Vol 14 (3) ◽  
pp. 2203-2213
Author(s):  
Essam J. Alyamani ◽  
Rayan Y. Booq ◽  
Ali H. Bahkali ◽  
Sulaiman A. Alharbi
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Saudi Arabia ◽  
Removal Rate ◽  
Groundwater Resources ◽  
Nitrate Removal ◽  
Reduction Rate ◽  
Denitrifying Bacteria ◽  
Molecular Techniques ◽  
Microbial Cellulose ◽  
Denitrification Process

Groundwater is the main water source for many areas in Saudi Arabia and the only source of water in some areas. Many local studies have reported that high nitrate concentrations in some wells of groundwater. To provide safe drinking water, the excess amounts of nitrate have to be removed by bio-denitrification process. This study aims to develop a denitrifying biological filter using denitrifying bacteria immobilized on microbial cellulose for the removal of nitrates from water contaminated with nitrate. Denitrifying bacteria that can form biofilter on microbial cellulose were isolated from different regions in Saudi Arabia and were characterized by molecular techniques. They were evaluated for their ability to analyze nitrates and to develop biofilter to remove nitrates from contaminated water. In the results of this project, an optimal microbial cellulose production was achieved by Gluconacetobacter xylinus ATCC 23768 in the lab, which had facilitated the use of biofilter with the immobilized nitrate-reducing bacteria Pseudomonas aeruginosa. The reduction rate of nitrate was reached 1.9mg/L from the starting concentration of 100 mg/L after 18h. Promising results of nitrate removal rate on MC immobilized with Pseudomonas aeruginosa on biofilter at optimized lab conditions of pH, and proper carbon source were achieved. The results suggest that water contaminated with nitrate can be removed by the bio-denitrification process effectively.

Bioregeneration of Activated Carbon in a Fluidized GAC Bed Treating Bleached Kraft Mill Secondary Effluent

1994 ◽  
Vol 29 (5-6) ◽  
pp. 239-246 ◽  
Author(s):  
P. Vuoriranta ◽  
S. Remo
Keyword(s):  
Activated Carbon ◽  
Organic Carbon ◽  
Removal Rate ◽  
Physical Adsorption ◽  
Reduction Rate ◽  
Pilot Scale ◽  
Temporary Increase ◽  
Secondary Effluent ◽  
Kraft Mill ◽  
Aox Removal

Secondary effluent from a bleached kraft mill activated sludge plant was treated in a pilot scale fluidized bed to remove residual organic carbon and AOX. Granular activated carbon was used as an adsorbent and support material for biomass. Physical adsorption and biodegradation were followed in a period of 18 weeks. Reduction of dissolved organic carbon was 57% throughout the period, mean load being 0.9 g of DOC/kg activated carbon in a day. AOX removal was more efficient, 70-90%. Reduction rate decreased in the course of time but could be partly recovered with addition of nutrients (P, N) to the nutrient deficient feed. A parallel experimental reactor was regenerated with ultrasonication/infrared - treatment. Physical regeneration gave a remarkable but temporary increase in the removal rate. A stable share of the total removal of DOC, 20-30%, was due to biodegradation and bioregeneration.

scholarly journals Ochrobactrum anthropi used to control ammonium for nitrate removal by starch-stabilized nanoscale zero valent iron

2017 ◽  
Vol 76 (7) ◽  
pp. 1827-1832 ◽  
Author(s):  
Jun Zhou ◽  
Qianyu Sun ◽  
Dan Chen ◽  
Hongyu Wang ◽  
Kai Yang
Keyword(s):  
Nitrate Reduction ◽  
Removal Rate ◽  
Nitrate Removal ◽  
Reduction Rate ◽  
Reduction Process ◽  
Zero Valent Iron ◽  
Ochrobactrum Anthropi ◽  
Iron Corrosion ◽  
Combined System ◽  
Nanoscale Zero Valent Iron

In this study, the hydrogenotrophic denitrifying bacterium Ochrobactrum anthropi was added in to the process of nitrate removal by starch-stabilized nanoscale zero valent iron (nZVI) to minimize undesirable ammonium. The ammonium control performance and cooperative mechanism of this combined process were investigated, and batch experiments were conducted to discuss the effects of starch-stabilized nZVI dose, biomass, and pH on nitrate reduction and ammonium control of this system. The combined system achieved satisfactory performance because the anaerobic iron corrosion process generates H2, which is used as an electron donor for the autohydrogenotrophic bacterium Ochrobactrum anthropi to achieve the autohydrogenotrophic denitrification process converting nitrate to N2. When starch-stabilized nZVI dose was increased from 0.5 to 2.0 g/L, nitrate reduction rate gradually increased, and ammonium yield also increased from 9.40 to 60.51 mg/L. Nitrate removal rate gradually decreased and ammonium yield decreased from 14.93 to 2.61 mg/L with initial OD600 increasing from 0.015 to 0.080. The abiotic Fe0 reduction process played a key role in nitrate removal in an acidic environment and generated large amounts of ammonium. Meanwhile, the nitrate removal rate decreased and ammonium yield also reduced in an alkaline environment.

scholarly journals Investigating the performance of agricultural wastes and their ashes in removing phenol from leachate in a fixed-bed column

2020 ◽  
Vol 81 (10) ◽  
pp. 2109-2126 ◽  
Author(s):  
Seyed Omid Ahmadinejad ◽  
Seyed Taghi Omid Naeeni ◽  
Zahra Akbari ◽  
Sara Nazif
Keyword(s):  
Activated Carbon ◽  
Large Scale ◽  
Fixed Bed ◽  
Walnut Shell ◽  
Continuous Systems ◽  
Phenol Removal ◽  
Adsorption Method ◽  
Fixed Bed Column ◽  
Saturation Time ◽  
Coconut Shell Activated Carbon

Abstract One of the major pollutants in leachate is phenol. Due to safety and environmental problems, removal of phenol from leachate is essential. Most of the adsorption studies have been conducted in batch systems. Practically, large-scale adsorption is carried out in continuous systems. In this research, the adsorption method has been used for phenol removal from leachate by using walnut shell activated carbon (WSA) and coconut shell activated carbon (CSA) as adsorbents in a fixed-bed column. The effect of adsorbent bed depth, influent phenol concentration and type of adsorbent on adsorption was explored. By increasing the depth of the adsorbent bed in the column, phenol removal efficiency and saturation time increase significantly. Also, by increasing the influent concentration, saturation time of the column decreases. To predict the column performance and describe the breakthrough curve, three kinetic models of Yon-Nelson, Adams-Bohart and Thomas were applied. The results of the experiments indicate that there is a good match between the results of the experiment and the predicted results of the models.

scholarly journals Catalytic Oxidation of 4-Hydroxybenzoic Acid on Activated Carbon in Batch Autoclave and Fixed-Bed Reactors

2007 ◽  
Vol 46 (25) ◽  
pp. 8388-8396 ◽  
Author(s):  
Carmen Creanga Manole ◽  
Carine Julcour-Lebigue ◽  
Anne-Marie Wilhelm ◽  
Henri Delmas
Keyword(s):  
Activated Carbon ◽  
Catalytic Oxidation ◽  
Fixed Bed ◽  
Hydroxybenzoic Acid ◽  
Fixed Bed Reactors

Ammonia adsorption in a fixed bed of activated carbon

2007 ◽  
Vol 98 (4) ◽  
pp. 886-891 ◽  
Author(s):  
C RODRIGUES ◽  
D DEMORAESJR ◽  
S DANOBREGA ◽  
M BARBOZA
Keyword(s):  
Activated Carbon ◽  
Fixed Bed ◽  
Ammonia Adsorption
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