The effects of pH and addition of an organic buffer (HEPES) on nitrate transformation in Fe0-water systems

1998 ◽  
Vol 38 (7) ◽  
pp. 107-115 ◽  
Author(s):  
Lara L. Zawaideh ◽  
Tian C. Zhang
Keyword(s):  
Nitrate Nitrogen ◽  
Batch Reactor ◽  
Nitrate Removal ◽  
Zero Valent Iron ◽  
Contaminated Water ◽  
Batch Reactors ◽  
Operational Parameters ◽  
Wide Ph Range ◽  
Effects Of Ph ◽  
Ph Range

The feasibility of using zero-valent iron (Fe0) powder to remediate nitrate-contaminated water was studied using bench-scale batch reactors. Operational parameters, such as Fe0 dosage (w/v), initial concentration of nitrate-nitrogen, pH, and the use of an organic buffer (HEPES) were studied, specifically focusing on the effects of pH and the addition of HEPES on nitrate transformation using zero-valent iron powder. Nitrate-nitrogen was removed by 94% when 0.01M of HEPES was added to a non-shaking batch reactor containing 20 mg/l nitrate-nitrogen and 4% (w/v) of Fe0. Shaking was proved to be more efficient than no shaking. Using the response surface methodology it was found that nitrate removal was closely related to pH. At low pH (e.g., pH < 2), the nitrate removal was fast and efficient (95% to 100%). At high pH (e.g., pH > 11), the transformation of nitrate was fast and efficient only for low concentration of nitrate in the Fe0-H2O system. At normal pH range (pH = 6 to 8), nitrate removal was usually lower than 50% without buffer treatment. The addition of the organic buffer (HEPES) could greatly enhance the nitrate transformation in a wide pH range (e.g., pH = 2 to 11).

EFFECTS OF pH AND NITROGEN SOURCES ON GROWTH OF MICROCYSTIS AERUGINOSA KÜTZ.

1962 ◽  
Vol 8 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Jack McLachlan ◽  
P. R. Gorham
Keyword(s):  
Growth Inhibition ◽  
Microcystis Aeruginosa ◽  
Nitrate Nitrogen ◽  
Nitrogen Sources ◽  
Cesium Chloride ◽  
Potassium Nitrate ◽  
Degree Of Ionization ◽  
Ph Values ◽  
Effects Of Ph ◽  
Ph Range

Microcystis aeruginosa Kütz. (strain NRC-1) grew equally well throughout the pH range 6.5 to 10 when provided with suitable media. Toxicity of tris(hydroxymethyl)aminomethane (TRIS) towards the alga was found to decrease as the pH decreased and could be correlated with the degree of ionization of the TRIS molecule. Other organic buffers examined were either toxic at all concentrations and pH values tested or promoted lysis. When TRIS was used as a buffer, higher concentrations of cesium chloride and potassium nitrate were tolerated without growth inhibition at pH 6.5 than at 7.5. In the presence of TRIS, Microcystis grew equally well with nitrate, ammonium, or urea as nitrogen sources. Eight out of 20 amino compounds examined served as nitrogen sources in TRIS-buffered medium, but growth was poorer than with nitrate nitrogen.

Experimental effect of medium ratio on removal efficiency of nitrate nitrogen in groundwater by zero-valent iron, activated carbon and zeolite

2019 ◽  
Vol 19 (6) ◽  
pp. 1636-1642
Author(s):  
Sizhi Cao ◽  
Peigui Liu ◽  
Mingchao Liu ◽  
Gang Wang ◽  
Zaili Li ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Nitrate Nitrogen ◽  
Nitrogen Concentration ◽  
Nitrate Removal ◽  
Ammonia Nitrogen ◽  
Coarse Sand ◽  
Zero Valent Iron ◽  
Nitrite Nitrogen ◽  
Rich Solution ◽  
Set Up

Abstract In this study, column experiments in the laboratory were set up to examine how the concentrations of nitrate nitrogen, nitrite nitrogen, and ammonia nitrogen changed when a nitrate-rich solution was passed through a medium comprising zero-valent iron, activated carbon, zeolite, and coarse sand. We varied the proportions of the components of the medium to determine how it influenced the nitrate removal and nitrogen fractions. Three different scenarios were used, with: (1) iron, activated carbon, and coarse sand at a ratio of 3:1:6; (2) iron, activated carbon, and zeolite at a ratio of 3:1:6; and (3) iron, activated carbon, and zeolite at a ratio of 3:3:4. The nitrate nitrogen concentration decreased from 25 mg/L to 2 mg/L in the first scenario. Removal was better when zeolite was added to the medium as most of the nitrate nitrogen broke down to ammonia nitrogen, with nitrite nitrogen as an intermediate product. The results of the tests showed that nitrate removal was best when the medium was iron, activated carbon, and zeolite, mixed at a ratio of 3:1:6. This study provides a scientific reference for in situ remediation of nitrate pollution in groundwater.

Sequencing batch reactor as a post-treatment of anaerobically treated dairy effluent

2006 ◽  
Vol 54 (2) ◽  
pp. 199-206 ◽  
Author(s):  
A. Benítez ◽  
A. Ferrari ◽  
S. Gutierrez ◽  
R. Canetti ◽  
A. Cabezas ◽  
...  
Keyword(s):  
Batch Reactor ◽  
Anaerobic Treatment ◽  
Post Treatment ◽  
Operating Conditions ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Operational Parameters ◽  
Reactor Operation ◽  
Set Up ◽  
The Stability

Wastewater from dairy industries, characterized by its high COD content and relative high COD/TKN ratio, requires post-treatment after anaerobic treatment to complete the removal of organic matter and nutrients. Due to its simplicity, robustness and low maintenance costs, sequencing batch reactors (SBR) result in an attractive system, especially in case of small dairy industries in order to comply with the emission standards. The goal of this work was to determine the operational parameters, optimize the performance, and study the stability of the microbial population of a SBR system for the post-treatment of an anaerobic pond effluent. High and stable removal of COD and TKN was achieved in the reactor, which can easily be set up in dairy industries. An active nitrifying population was selected during reactor operation and maintained relatively stable, while the heterotrophic (total and denitrifying) communities were more unstable and susceptible to changes in the operating conditions.

Nitrate removal by simultaneous sulfur utilizing autotrophic and heterotrophic denitrification under different organics and alkalinity conditions: batch experiments

2003 ◽  
Vol 47 (1) ◽  
pp. 237-244 ◽  
Author(s):  
S.E. Oh ◽  
M.S. Bum ◽  
Y.B. Yoo ◽  
A. Zubair ◽  
I.S. Kim
Keyword(s):  
Production Rate ◽  
Organic Compounds ◽  
Nitrate Nitrogen ◽  
Nitrogen Concentration ◽  
Nitrate Removal ◽  
Batch Reactors ◽  
Autotrophic Denitrification ◽  
Batch Experiments ◽  
Sulfate Production ◽  
Heterotrophic Denitrification

The effect of various organic compounds were tested using lab-scale batch reactors. At sufficient alkalinity, the initial nitrate nitrogen concentration of 100 mg/L was completely reduced in all batch reactors. Sulfate production decreased by the addition of organics. The concentration range of organics used in this experiment did not inhibit autotrophic denitrification except for propionate. Propionate inhibited autotrophic denitrification a little, indicated by a lower sulfate production rate. Biomass in suspension increased with higher initial organic concentrations, showing higher DOC consumption. As the concentration of organics increased, alkalinity increased accordingly. Under the conditions of low alkalinity, in the case of a control reactor without organics, only about 30% of the initial nitrate was reduced. With half the theoretically required dosage of methanol, the denitrification rates increased slightly. When ethanol, acetate, and propionate were used, denitrification went to completion. When excess organics was added, however, sulfate production was significantly decreased. Interestingly, even when small amounts of organics were added, autotrophic denitrification was promoted as indicated by the sulfate production.

scholarly journals Enhanced removal of selenate from mining effluent by H2O2/HCl-pretreated zero-valent iron

2018 ◽  
Vol 78 (11) ◽  
pp. 2404-2413 ◽  
Author(s):  
Bing Wu ◽  
Huichao Jia ◽  
Zhe Yang ◽  
Chao Shan ◽  
Jingxia Weng ◽  
...  
Keyword(s):  
Passive Layer ◽  
Zero Valent Iron ◽  
Mining Effluent ◽  
Acid Washing ◽  
Initial Ph ◽  
Wide Ph Range ◽  
Adsorption Reduction ◽  
Ph Range ◽  
Co Precipitation ◽  
Direct Use

Abstract Direct use of zero-valent iron (ZVI) in reductive removal of selenate (Se(VI)) is inefficient due to the intrinsic passive layer of ZVI. Here we observed that ZVI pretreated with H2O2 (P-ZVI-O) performs much better in Se(VI) removal from a mining effluent than other three modes of ZVI alone, acid washing ZVI (P-ZVI-A), and simultaneous addition of H2O2 and ZVI (ZVI-O) as well. The P-ZVI-O exhibits exceptionally high Se(VI) removal at a low dosage, wide pH range, with Se dropping down from 93.5 mg/L to <0.4 μg/L after 7-h reaction. Interestingly, the initial pH (2–6) of the mining effluent exerted little influence on the final Se(VI) removal. H2O2/HCl pretreatment results in the formation of various reducing corrosion products (e.g. Fe3O4, FeO and Fe2+), which greatly favors the efficient Se(VI) removal. In addition, surface-bound Fe2+ ions participated in the reduction of Se(VI). Combined with the influence of Se valence as well as pH and Fe2+ (whether dissolved or surface bound), it is deduced that the P-ZVI-O mode induced efficient Se(VI) removal via the adsorption-reduction and/or co-precipitation. This study demonstrates that H2O2/HCl pretreatment of ZVI is a very promising option to enhance the efficiency of reductive removal of Se(VI) from real effluents.

scholarly journals The Use of Lignin as a Microbial Carrier in the Co-Digestion of Cheese and Wafer Waste

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2073 ◽  
Author(s):  
Agnieszka A. Pilarska ◽  
Agnieszka Wolna-Maruwka ◽  
Krzysztof Pilarski ◽  
Damian Janczak ◽  
Krzysztof Przybył ◽  
...  
Keyword(s):  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Cell Immobilization ◽  
Total Alkalinity ◽  
Batch Reactors ◽  
Adhesive Properties ◽  
Volatile Solids ◽  
Wide Ph Range ◽  
Ph Range ◽  
Microbiological Analyses

The aim of the article was to present the effects of lignin grafted with polyvinylpyrrolidone (PVP) as a microbial carrier in anaerobic co-digestion (AcoD) of cheese (CE) and wafer waste (WF). Individual samples of waste cheese and wafers were also tested. The PVP modifier was used to improve the adhesive properties of the carrier surface. Lignin is a natural biopolymer which exhibits all the properties of a good carrier, including nontoxicity, biocompatibility, porosity, and thermal stability. Moreover, the analysis of the zeta potential of lignin and lignin combined with PVP showed their high electrokinetic stability within a wide pH range, that is, 4–11. The AcoD process was conducted under mesophilic conditions in a laboratory by means of anaerobic batch reactors. Monitoring with two standard parameters: pH and the VFA/TA ratio (volatile fatty acids-to-total alkalinity ratio) proved that the process was stable in all the samples tested. The high share of N–NH4+ in TKN (total Kjeldahl nitrogen), which exceeded 90% for WF+CE and CE at the last phases of the process, proved the effective conversion of nitrogen forms. The microbiological analyses showed that eubacteria proliferated intensively and the dehydrogenase activity increased in the samples containing the carrier, especially in the system with two co-substrates (WF+CE/lignin) and in the waste cheese sample (CE/lignin). The biogas production increased from 1102.00 m3 Mg−1 VS (volatile solids) to 1257.38 m3 Mg−1 VS in the WF+CE/lignin sample, and from 881.26 m3 Mg−1 VS to 989.65 m3 Mg−1 VS in the CE/lignin sample. The research results showed that the cell immobilization on lignin had very positive effect on the anaerobic digestion process.

Treatment characteristics and effects of nanoparticle zero-valent iron (nZVI) powder on nitrogen removal efficiency for sewage treatment

2014 ◽  
Vol 49 (3) ◽  
pp. 273-284 ◽  
Author(s):  
Mi-Sug Kim ◽  
Dong-Heui Kwak
Keyword(s):  
Removal Efficiency ◽  
Nitrogen Removal ◽  
Batch Reactor ◽  
Nitrate Removal ◽  
Sewage Treatment ◽  
Synthetic Zeolite ◽  
Zero Valent Iron ◽  
Silica Sand ◽  
Experimental Conditions ◽  
N Removal

This study aims at estimating nanoparticle typed zero-valent iron (nZVI) process as an advanced nitrogen removal technique. To focus on investigating characteristics and effects of nZVI on nitrogen removal for sewage treatment, batch reactor experiments were conducted to reduce excessive nitrate nitrogen (NO3-N). To improve NO3-N removal efficiency and to find a supporter or alternative of nZVI, silica sand, synthetic zeolite, and a mixture of silica sand, synthetic zeolite, and nZVI were used in the experiments. As a result of this study, the chemical denitrification by nZVI attracted on the magnet surface may be useful for total nitrogen removal in conventional sewage and wastewater treatment plants under the optimal conditions, and application of silica sand also is an excellent adsorbent or media for N-component removal and a supporter as well. This study concludes the end product in this study may be nitrogen gas (N2) through Fe0 reaction with O2 and NO3− in aerobic nZVI (Fe0)–H2O system. Future study is required to examine the competition of nZVI between nitrate and many other compounds depending upon various experimental conditions for improving the nitrate removal efficiency and impeding the ammonium generation.

scholarly journals Removal of Nitrate by Bimetallic Copper-nanoscale Zero-valent Iron (Cu-nZVI): Using 2k Full Factorial Design

2014 ◽  
pp. 15-24 ◽  
Author(s):  
Nalinee Krasae ◽  
Kitirote Wantala ◽  
Puek Tantriratna ◽  
Nurak Grisdanurak
Keyword(s):  
Factorial Design ◽  
Batch Reactor ◽  
Nitrate Removal ◽  
Full Factorial Design ◽  
Zero Valent Iron ◽  
Impregnation Method ◽  
Nanoscale Zero Valent Iron ◽  
Acidic Conditions ◽  
Neutral Conditions ◽  
Full Factorial

Enhanced nitrate reduction of nanoscale zero valent iron (nZVI) by Cu prepared by impregnation method was studied in this work. Using a full factorial design, the performance of nZVI with and without Cu on surface in acidic and neutral conditions was investigated. Static batch reactor was selected in this study to investigate the effects of the independent variables such as catalysts (nZVI with and without Cu), initial pH of solutions (3, 7), and reaction times (10, 30 min). The results found that nitrate removal over Cu-nZVI was greater than that of nZVI by about 37% and 36% at pH 3 and pH 7 for 30 min, respectively. Both catalysts were effective in removing nitrate under acidic conditions (pH 3). Thus, this study concludes that nZVI can enhance the performance by Cu in nitrate removal. Moreover, acidic conditions were more effective than neutral conditions in removing nitrate.

Estimation of oxygen transfer rate in sequencing batch reactor

1996 ◽  
Vol 34 (3-4) ◽  
pp. 413-420
Author(s):  
Y. C. Liao ◽  
D. J. Lee
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Transfer ◽  
Transfer Rate ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Oxygen Transfer Rate ◽  
Intermittent Aeration ◽  
Transient Effects ◽  
Operational Parameters ◽  
Transient Model

Transient model of oxygen transfer rate in a sequencing batch reactor is derived and solved numerically. The dissolved oxygen response under several conditions is analyzed. Effects of operational parameters and liquid bath height are studied. When with short, intermittent aeration periods, the transient effects on oxygen transfer rate may be substantial and should be taken into considerations. An example considering bioreaction is also given.

A simulation apparatus for the experimental study of batch reactor control methods

1986 ◽  
Vol 51 (6) ◽  
pp. 1259-1267
Author(s):  
Josef Horák ◽  
Petr Beránek
Keyword(s):  
Experimental Study ◽  
Closed Loop ◽  
Dynamic Properties ◽  
Batch Reactor ◽  
Exothermic Reaction ◽  
Electric Heating ◽  
Batch Reactors ◽  
Exchange Area ◽  
The Stability ◽  
Methods Of Control

A simulation apparatus for the experimental study of the methods of control of batch reactors is devised. In this apparatus, the production of heat by an exothermic reaction is replaced by electric heating controlled by a computer in a closed loop; the reactor is cooled with an external cooler whose dynamic properties can be varied while keeping the heat exchange area constant. The effect of the cooler geometry on its dynamic properties is investigated and the effect of the cooler inertia on the stability and safety of the on-off temperature control in the unstable pseudostationary state is examined.

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