scholarly journals Efficient Hydrogen Generation and Total Nitrogen Removal for Urine Treatment in a Neutral Solution Based on a Self-Driving Nano Photoelectrocatalytic System

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2777
Author(s):  
Pengbo Wang ◽  
Jinhua Li ◽  
Yang Xu ◽  
Changhui Zhou ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Total Nitrogen ◽  
Hydrogen Generation ◽  
Removal Rate ◽  
Photovoltaic Cell ◽  
Reaction Rate Constant ◽  
Alkaline Condition ◽  
Neutral Solution ◽  
Recovery Method ◽  
Self Bias ◽  
Urine Treatment

Urine is the main source of nitrogen pollution, while urea is a hydrogen-enriched carrier that has been ignored. Decomposition of urea to H2 and N2 is of great significance. Unfortunately, direct urea oxidation suffers from sluggish kinetics, and needs strong alkaline condition. Herein, we developed a self-driving nano photoelectrocatalytic (PEC) system to efficiently produce hydrogen and remove total nitrogen (TN) for urine treatment under neutral pH conditions. TiO2/WO3 nanosheets were used as photoanode to generate chlorine radicals (Cl•) to convert urea-nitrogen to N2, which can promote hydrogen generation, due to the kinetic advantage of Cl–/Cl• cyclic catalysis. Copper nanowire electrodes (Cu NWs/CF) were employed as the cathode to produce hydrogen and simultaneously eliminate the over-oxidized nitrate-nitrogen. The self-driving was achieved based on a self-bias photoanode, consisting of confronted TiO2/WO3 nanosheets and a rear Si photovoltaic cell (Si PVC). The experiment results showed that hydrogen generation with Cl• is 2.03 times higher than in urine treatment without Cl•, generating hydrogen at 66.71 μmol h−1. At the same time, this system achieved a decomposition rate of 98.33% for urea in 2 h, with a reaction rate constant of 0.0359 min−1. The removal rate of total nitrogen and total organic carbon (TOC) reached 75.3% and 48.4% in 2 h, respectively. This study proposes an efficient and potential urine treatment and energy recovery method in neutral solution.

Preparation of Calcium Sulfate Anhydrate Whisker and a Primary Investigation of its Arsenic Removal Performance

2013 ◽  
Vol 690-693 ◽  
pp. 1013-1019
Author(s):  
Xiao Juan Chen ◽  
Liu Chun Yang ◽  
Jun Feng Zhang ◽  
Yan Huang
Keyword(s):  
Calcium Sulfate ◽  
Arsenic Removal ◽  
Removal Rate ◽  
Optical Microscope ◽  
Alkaline Condition ◽  
Crystal Water ◽  
Arsenic Uptake ◽  
Ft Ir ◽  
High Removal Rate ◽  
Calcium Sulfate Whisker

Calcium sulfate whisker (CSW) was prepared through the method of cooling recrystallization. In an attempt to develop its new application in environmental protection, we investigated the effect of calcination on the material properties and arsenic uptake performance of calcium sulfate whisker anhydrate (CSAW), which was obtained from CSW calcined at 600 °C for 2 h. Moreover, XRD, SEM, optical microscope, and FT-IR were used to characterize CSW samples. It was found that calcination played an important role in the whisker structure through changing the content of crystal water and the morphology. The CSAW material exhibited a high removal rate of As3+/As5+under strongly alkaline condition.

Total nitrogen removal from high-strength ammonia recycle stream using a single submerged attached growth bioreactor

2007 ◽  
Vol 55 (8-9) ◽  
pp. 59-65 ◽  
Author(s):  
A. Onnis-Hayden ◽  
P.B. Pedros ◽  
J. Reade
Keyword(s):  
Total Nitrogen ◽  
Nitrogen Removal ◽  
Removal Rate ◽  
Treatment Plant ◽  
High Strength ◽  
Nitrogen Loading ◽  
Digested Sludge ◽  
Attached Growth ◽  
Anaerobically Digested Sludge ◽  
Total Nitrogen Removal

An experimental study investigating the nitrogen removal efficiency from the recycle stream generated in the dewatering facility of the anaerobically digested sludge at the Deer Island wastewater treatment plant (WWTP) in Boston was conducted using a single submerged attached growth bioreactor (SAGB), designed for simultaneous nitrification and denitrification. The applied nitrogen loading to the reactor ranged from 0.7 to 2.27 kg-N/m3·d, and the corresponding total nitrogen (TN) removal rate ranged from 0.38 to 1.8 kg-N/m3·d. The observed nitrification rates varied from 0.42 kg-N/m3·d to 1.45 kg-N/m3·d with an ammonia load of 0.5 kg-N/m3·d and 1.8 kg-N/m3·d, respectively. An average nitrification efficiency of 91% was achieved throughout the experiment. Denitrification efficiency varied from 55%, obtained without any addition of carbon source, to 95% when methanol was added in order to obtain a methanol/nitrate ratio of about 3 kg methanol/kg NO3−-N.

Combining artificial aeration and biological zeolite mulch for nitrogen removal from eutrophic water bodies

2020 ◽  
Vol 15 (1) ◽  
pp. 151-159
Author(s):  
Cheng Lu ◽  
Wen Cheng ◽  
Min Wang ◽  
Zhiwei Zhou
Keyword(s):  
Total Nitrogen ◽  
Nitrogen Removal ◽  
Removal Rate ◽  
Nitrogen Concentration ◽  
Combined Treatment ◽  
Ammoniacal Nitrogen ◽  
Nitrogen Species ◽  
Artificial Aeration ◽  
Total Nitrogen Concentration ◽  
Eutrophic Water

Abstract Endogenous nitrogen pollution can be a major cause of eutrophication. Nitrogen species release from sediments can be reduced by biologically-enforced zeolite mulch or water column aeration. This study was about their combined effects. Water and surface sediment samples from the Yangzhou ancient canal were aerated and biozeolite mulching was applied separately and in combination for 81 days, while the nitrogen species removal rate was recorded. The combination of aeration and biozeolite mulching removed >95% of the ammoniacal-nitrogen in 15 days. This was better than either the blank control or biozeolite mulch without aeration. The ammoniacal-nitrogen concentration was lowered faster by combined treatment than by aeration alone. Nitrate nitrogen was only detected during aeration between days 10 and18, and reached lower concentration in the presence of biozeolite. Nitrate was formed during aeration but its concentrations were higher and more variable in the absence of biozeolite; that is, mulching stabilized nitrate formation. The total nitrogen concentration reached its lowest levels after 81 days with biozeolite treatment alone, with 78% total nitrogen removal, whereas combined aeration with biozeolite achieved 41%. This shows that biozeolite mulching can remove nitrogen in eutrophic waters, even without aeration.

Performance of Modified Graphite Felt as Cathode in the Electro-Fenton System

2020 ◽  
Vol 12 (3) ◽  
pp. 350-356 ◽  
Author(s):  
Dongbao Song ◽  
Junfeng Li ◽  
Weiwei Liu ◽  
Zhaoyang Wang ◽  
Chun Zhao ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Removal Rate ◽  
Electrical Energy ◽  
Degradation Process ◽  
Reaction Rate Constant ◽  
Production Performance ◽  
Impregnation Method ◽  
Application Performance ◽  
Graphite Felt ◽  
Fenton System

The graphite felt (GF) was modified by the impregnation method and the potentiostatic oxidation method to improve its application performance in the electro-Fenton (E-Fenton) system. Sulfuric acid and ammonia water were used as modifying reagents. After the GF was modified, its conductivity, adsorption performance and hydrogen peroxide production performance were improved. The original graphite felt (GF0) and the modified GF were used as cathode to degrade methylene blue in the E-Fenton system to explore the practical application performance. The reaction kinetics of the methylene blue degradation process was fitted. The results showed the degradation of methylene blue followed the first-order kinetics. The GF was modified by the potentiostatic oxidation with ammonia as modifying reagent (GFEN) had the best application performance in the E-Fenton system. Degradation of methylene blue for 30 min, the reaction rate constant of GFEN cathode system was 1.71 times higher than GF0 cathode system. The GFEN electrode was reused 10 times in the E-Fenton system, the removal rate of methylene blue was only decreased by 7.14%, and the current was only decreased by 4 mA, which showed its good stability. Finally, the comparison of the electrical energy per order (EE/O) values showed that GFEN can significantly improve the current efficiency of the E-Fenton system.

High-Concentration Nitrogen Removal by Anaerobic Ammonium Oxidation Process

2012 ◽  
Vol 518-523 ◽  
pp. 214-217
Author(s):  
Tao Hong Liao ◽  
Kang Huai Liu ◽  
Jia Chun Yang ◽  
Kenji Furukawa
Keyword(s):  
Total Nitrogen ◽  
Nitrogen Removal ◽  
Removal Rate ◽  
Nitrogen Concentration ◽  
Ammonia Nitrogen ◽  
Ammonium Oxidation ◽  
High Concentration ◽  
Total Nitrogen Concentration ◽  
Load Rate ◽  
Nitrogen Load Rate

This experiment aimed to explore the effect of high- concentration nitrogen removal by Anaerobic ammonium oxidation process. The mixed liquor suspended solid(MLSS)was 510 mg/L. In the beginning of the experiment, the inflow concentration rate of ammonia nitrogen and nitrite nitrogen was about 1:1.3 and the total nitrogen concentration was low. When the reactor reached the ideal treatment effect then gradually increased the total nitrogen concentration, until reaching the maximum nitrogen load rate(NLR) of the reactor. In the temperature of 34.4 °C, PH was 7.23, the inflow concentration of ammonia nitrogen was 223.3 mg. N/L, the inflow concentration nitrite nitrogen was 289.7 mg. N/L, the dissolved oxygen (DO) was 2.3 mg. N/L, the nitrogen load rate (NLR) was 6.08 kg. N / (m3. d), the nitrogen removal rate (NRR) was 5.60 kg. N / (m3. d), the total nitrogen (TN) removal rate was 92.2%, under this conditions, the reactor achieved the best effect.

scholarly journals Treatment performance, nitrous oxide production and microbial community under low-ammonium wastewater in a CANON process

2017 ◽  
Vol 76 (12) ◽  
pp. 3468-3477 ◽  
Author(s):  
Weixing Mi ◽  
Jianqiang Zhao ◽  
Xiaoqian Ding ◽  
Guanghuan Ge ◽  
Rixiang Zhao
Keyword(s):  
Nitrous Oxide ◽  
Total Nitrogen ◽  
Nitrogen Removal ◽  
Ammonia Oxidation ◽  
Removal Rate ◽  
Biofilm Reactor ◽  
Ammonium Concentration ◽  
Nitrous Oxide Production ◽  
Total Nitrogen Removal ◽  
Canon Process

Abstract To investigate the characteristics of anaerobic ammonia oxidation for treating low-ammonium wastewater, a continuous-flow completely autotrophic nitrogen removal over nitrite (CANON) biofilm reactor was studied. At a temperature of 32 ± 1 °C and a pH between 7.5 and 8.2, two operational experiments were performed: the first one fixed the hydraulic retention time (HRT) at 10 h and gradually reduced the influent ammonium concentrations from 210 to 50 mg L−1; the second one fixed the influent ammonium concentration at 30 mg L−1 and gradually decreased the HRT from 10 to 3 h. The results revealed that the total nitrogen removal efficiency exceeded 80%, with a corresponding total nitrogen removal rate of 0.26 ± 0.01 kg N m−3 d−1 at the final low ammonium concentration of 30 mg L−1. Small amounts of nitrous oxide (N2O) up to 0.015 ± 0.004 kg m−3 d−1 at the ammonium concentration of 210 mg L−1 were produced in the CANON process and decreased with the decrease in the influent ammonium loads. High-throughput pyrosequencing analysis indicated that the dominant functional bacteria ‘Candidatus Kuenenia’ under high influent ammonium levels were gradually succeeded by Armatimonadetes_gp5 under low influent ammonium levels.

Study on the Conversion of Ammonia by Electrochemical Oxidation

2013 ◽  
Vol 807-809 ◽  
pp. 1355-1361
Author(s):  
Fang Yuan ◽  
Jin Guo Dai ◽  
Zhi Hui Liang ◽  
Hong Bo Fan ◽  
Si Hao Lv
Keyword(s):  
Electrochemical Oxidation ◽  
Removal Efficiency ◽  
Total Nitrogen ◽  
Ammonia Removal ◽  
Alkaline Condition ◽  
High Concentration ◽  
Oxidation Method ◽  
Electrolysis Process ◽  
Initial Ph ◽  
Nitrate And Nitrite

The removal of high concentration ammonia in wastewater was investigated by an indirect electrochemical oxidation method using titanium electrodes coated with ruthenium and iridium (RuO2-IrO2-TiO2/Ti). The effect of different initial pH on ammonia removal by electrochemical oxidation was studied. The concentrations variation of ammonia, total nitrogen, nitrate nitrite, and free cholorines, chloramines was analyzed under the conditions with and without pH controlling. The results indicate that ammonia removal efficiency was higher under the moderate alkaline condition than that under neutral one. During the electrolysis process, nitrate and nitrite concentrations were very low, even below their detecting limits. The concentrations of free chlorines and chloramines were significantly affected by pH, as trichloramine and free chlorines were mainly produced in the reaction without pH controlling, while monochloramine was mainly produced in a stable alkalescene.

Characteristics of hydrogen generation from water splitting by polymer electrolyte electrochemical cell directly connected with concentrated photovoltaic cell

2013 ◽  
Vol 38 (34) ◽  
pp. 14424-14432 ◽  
Author(s):  
Katsushi Fujii ◽  
Shinichiro Nakamura ◽  
Masakazu Sugiyama ◽  
Kentaroh Watanabe ◽  
Behgol Bagheri ◽  
...  
Keyword(s):  
Polymer Electrolyte ◽  
Water Splitting ◽  
Hydrogen Generation ◽  
Electrochemical Cell ◽  
Photovoltaic Cell

scholarly journals Plant growth and total Nitrogen absorption rate in leachate with water hyacinth (Eichhornia crassipes)

2019 ◽  
Vol 3 (2) ◽  
pp. 117-126
Author(s):  
Dyah Wahyu Wijayanti
Keyword(s):  
Plant Growth ◽  
Total Nitrogen ◽  
Rate Constant ◽  
Water Hyacinth ◽  
Eichhornia Crassipes ◽  
Absorption Rate ◽  
Reaction Rate ◽  
Simple Technique ◽  
Reaction Rate Constant ◽  
Absorption Rate Constant

Phytoremediation is a simple technique of wastewater  processing by utilizing the plant activity to vanish, replace and stabilize or destroy the pollutant either organic compound or inorganic. This research utilizes Eichhornia crassipes as the biofilter in handling the leachate produced from organic waste degradation. The purposes of this research are to find out the plant growth rate and total Nitrogen (N) absorption in leachate by the Eichhornia crassipes. The experiment shows that the concentration of leachate affects the absorption rate of total N and wet weight of the plant. The model was fit to the experimental data. The metabolism reaction rate constant ( ) and absorption rate constant ( ) at leachate concentration 5%, 10%, 15%, 20%, 25% and 30% were measured. The highest reaction rate constant and absorption rate constant were  5% of leachate concentration where = 0.008042/day and = 2.30811/day, whilst at the leachate concentration of 30% reaction rate constant and absorption rate constant were the lowest where it reached = 0.00029/day and = 0.04576/day. The absorption ability of water hyacinth to absorb the N which contained in the leachate was affected by the metabolism reaction rate of nitrogen in the plant and the reaction rate of nitrogen degradation into ammonia (NH4) and nitric ion (NO3) in the plant root. The leachate concentration affected the efficiency of N absorption by the water hyacinth. The efficiency of N absorption at leachate concentration of 5; 10; 15; 20; 25 and 30 were 89.81%, 68.99%, 49.51%, 36.32%, 30.28% and 21.64% respectively. Overall, this technique presents a simple technique approach and the utilization of elements contained in the leachate as the nutrition for plant.

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