Simultaneous oxidation and reduction treatments of polluted water by a bio-electro reactor

1996 ◽  
Vol 34 (9) ◽  
pp. 101-108 ◽  
Author(s):  
M. Kuroda ◽  
T. Watanabe ◽  
Y. Umedu
Keyword(s):  
Aqueous Solution ◽  
Organic Matter ◽  
Electric Current ◽  
Removal Efficiency ◽  
Concentration Ratio ◽  
Nitrate Removal ◽  
Hydrogen Gas ◽  
Polluted Water ◽  
Simultaneous Oxidation ◽  
Denitrifying Microorganisms

Application of a bio-electro reactor for treatment of various kinds of polluted water was investigated experimentally. Aqueous solution of nitrate, ammonium and/or organic matter were used as synthetic polluted water. Denitrification of the nitrate polluted water without organic matter proceeded effectively by utilizing hydrogen gas produced by electrolysis of water in the reactor. The bio-electro reactor was also available for the treatment of nitrate polluted water containing organic matter when the C/N concentration ratio was up to 1.0 under the condition of 100 mA of applied electric current. The nitrate removal efficiency from nitrate polluted water containing acetate at C/N=1.0 was more than 90% at 5 hours of HRT and 80% even at 2.8 h HRT. For the treatment of ammonium polluted water, nitrification and denitrification proceeded simultaneously in a bio-electro reactor where nitrifying and denitrifying microorganisms were immobilized on the electrodes. The results obtained in this study suggested that the bio-electro reactor system was capable to application for oxidation and reduction treatments of the nitrate and ammonium polluted water.

scholarly journals Nitrate Removal from Actual Wastewater by Coupling Sulfur-Based Autotrophic and Heterotrophic Denitrification under Different Influent Concentrations

Water ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 2913
Author(s):  
Feng Liu ◽  
Suqin Wang ◽  
Xuezhi Zhang ◽  
Feiyue Qian ◽  
Yaobing Wang ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Nitrate Removal ◽  
Operating Conditions ◽  
Coupled Systems ◽  
Polluted Water ◽  
Sequencing Analysis ◽  
Autotrophic Denitrification ◽  
Actual Wastewater ◽  
Denitrification Process ◽  
Heterotrophic Denitrification

Contamination of wastewater with organic-limited nitrates has become an urgent problem in wastewater treatment. The cooperating heterotrophic with sulfur autotrophic denitrification is an alternative process and the efficiency has been assessed in many studies treating simulated wastewater under different operating conditions. However, due to the complex and diverse nature of actual wastewater, more studies treating actual wastewater are still needed to evaluate the feasibility of collaborative denitrification. In this study, lab-scale experiments were performed with actual nitrate polluted water of two different concentrations, with glucose and sodium thiosulfate introduced as mixed electron donors in the coupling sulfur-based autotrophic and heterotrophic denitrification. Results showed that the optimum denitrification performance was exhibited when the influent substrate mass ratio of C/N/S was 1.3/1/1.9, with a maximum denitrification rate of 3.52 kg NO3−-N/(m3 day) and nitrate removal efficiency of 93% in the coupled systems. Illumina high-throughput sequencing analysis revealed that autotrophic, facultative, and heterotrophic bacteria jointly contributed to high nitrogen removal efficiency. The autotrophic denitrification maintained as the predominant process, while the second most prevalent denitrification process gradually changed from heterotrophic to facultative with the increase of influent concentration at optimum C/N/S ratio conditions. Furthermore, the initiation of dissimilatory nitrate reduction to ammonium (DNRA) was very pivotal in promoting the entire denitrification process. These results suggested that sulfur-based autotrophic coupled with heterotrophic denitrifying process is an alternative and promising method to treat nitrate containing wastewater.

scholarly journals Modeling of nitrate removal from aqueous solution by Fe-doped TiO2 under UV and solar irradiation using response surface methodology

2015 ◽  
Vol 17 (2) ◽  
pp. 379-388 ◽  
Keyword(s):  
Aqueous Solution ◽  
Response Surface Methodology ◽  
Solar Radiation ◽  
Response Surface ◽  
Removal Efficiency ◽  
Nitrate Removal ◽  
Operating Conditions ◽  
Solar Irradiation ◽  
Design Matrix ◽  
Statistical Tool

<div> <p>Nitrate is a common groundwater pollutant all over the world. In some regions of Iran, its levels are high enough to cause serious problems to human health and the environment<span dir="RTL">.</span> The objectives of this work were to evaluate the efficiency of Fe-doped TiO<sub>2</sub> nanoparticles at removing nitrate from aqueous solutions under UV and solar radiation and to model nitrate removal using response surface methodology techniques. In this study, a response surface methodology based on the Box&ndash;Behnken design matrix was used to describe the process of nitrate removal from an aqueous solution with four independent parameters, namely Fe-doped TiO<sub>2</sub> (dose 1-2 g l<sup>-1</sup>), nitrate concentration (25-100 mg l<sup>-1</sup>), contact time (10-120 min), and pH (4-9). The results indicated that the removal efficiency of nitrate in the presence of ultraviolet and solar radiation was 56.5 % and 21.8%, respectively. The removal efficiency of nitrate increased with time and initial concentration of nitrate. Analysis of variance (ANOVA) indicated that the proposed model was essentially in accordance with the experimental results with the correlation coefficient R<sup>2 </sup>= 0.9237 and Adj-R<sup>2</sup> = 0.8347. Response surface methodology (RSM) proved to be a powerful statistical tool for investigating the operating conditions for nitrate removal under UV irradiation.</p> </div> <p>&nbsp;</p>

Simultaneous COD removal and denitrification of wastewater by bio-electro reactors

1997 ◽  
Vol 35 (8) ◽  
pp. 161-168 ◽  
Author(s):  
M. Kuroda ◽  
T. Watanabe ◽  
Y. Umedu
Keyword(s):  
Organic Matter ◽  
Electric Current ◽  
Denitrifying Bacteria ◽  
Hydrogen Gas ◽  
Cod Removal ◽  
Hydrogen Donor ◽  
Continuous Treatment ◽  
Synthetic Wastewater ◽  
Internal Source ◽  
Nitrogen Gas

Application of a bio-electro reactor process for the treatment of wastewater containing nitrate and internal source of hydrogen donor as organic matter was experimentally investigated. The bio-electro reactor consisted of immobilized denitrifying bacteria electrode as cathode and carbon electrode as anode. Hydrogen gas was produced on the cathode surface by the electrolysis of water when electric current was applied, and immediately utilized to reduce biologically nitrate to nitrogen gas by the cathodic immobilized denitrifying bacteria. Consumption characteristics of organic matter and utilization of hydrogen gas derived from the electrolysis of water for denitrification was studied by batch experiments. Continuous treatment experiments using a synthetic wastewater containing nitrate and organic matter were carried out to investigate the denitrification and organic matter removal performances. Denitrification occurred with simultaneous utilization of organic matter existed as internal source of hydrogen donor in the wastewater and hydrogen gas by electrolysis of water. Hydrogen gas was utilized efficiently for denitrification even if excess amount of organic hydrogen donor existed in wastewater. In this bio-electro reactor system, it was confirmed that COD as well as nitrate was removed simultaneously by applied electric current in continuous experiment, though further investigation are necessary to analyze the COD removal by applied electric current in detail.

scholarly journals Environmentally Friendly Polyvinyl Alcohol−Alginate/Bentonite Semi-Interpenetrating Polymer Network Nanocomposite Hydrogel Beads as An Efficient Adsorbent for the Removal of Methylene Blue from Aqueous Solution

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 4000
Author(s):  
Mona A. Aziz Aljar ◽  
Suad Rashdan ◽  
Ahmed Abd El-Fattah
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Polyvinyl Alcohol ◽  
Removal Efficiency ◽  
Polymer Network ◽  
Interpenetrating Polymer Network ◽  
Polluted Water ◽  
Order Kinetic ◽  
Nanocomposite Hydrogel ◽  
Hydrogel Beads

Hazardous chemicals like toxic organic dyes are very harmful to the environment and their removal is quite challenging. Therefore there is a necessity to develop techniques, which are environment friendly, cost-effective and easily available in nature for water purification and remediation. The present research work is focused on the development` and characterization of the ecofriendly semi-interpenetrating polymer network (semi-IPN) nanocomposite hydrogels composed of polyvinyl alcohol (PVA) and alginate (Alg) hydrogel beads incorporating natural bentonite (Bent) clay as a beneficial adsorbent for the removal of toxic methylene blue (MB) from aqueous solution. PVA−Alg/Bent nanocomposite hydrogel beads with different Bent content (0, 10, 20, and 30 wt%) were synthesized via external ionic gelation method. The designed porous and steady structure beads were characterized by the use of Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM). The performance of the beads as MB adsorbents was investigated by treating aqueous solutions in batch mode. The experimental results indicated that the incorporation of Bent (30 wt%) in the nanocomposite formulation sustained the porous structure, preserved water uptake, and increased MB removal efficiency by 230% compared to empty beads. Designed beads possessed higher affinity to MB at high pH 8, 30 °C, and fitted well to pseudo-second-order kinetic model with a high correlation coefficient. Moreover, the designed beads had good stability and reusability as they exhibited excellent removal efficiency (90%) after six consecutive adsorption-desorption cycles. The adsorption process was found be combination of both monolayer adsorption on homogeneous surface and multilayer adsorption on heterogeneous surface. The maximum adsorption capacity of the designed beads system as calculated by Langmuir isotherm was found to be 51.34 mg/g, which is in good agreement with the reported clay-related adsorbents. The designed semi-IPN PVA−Alg/Bent nanocomposite hydrogel beads demonstrated good adsorbent properties and could be potentially used for MB removal from polluted water.

scholarly journals The removal performance of nitrates in the novel 3D-BERS with GAC and diversity of immobilized microbial communities treating nitrate-polluted water: Effects of pH and COD/NO3--N ratio

2021 ◽  
Vol 27 (2) ◽  
pp. 200526-0
Author(s):  
Mahdi Hassan ◽  
Guangcan Zhu ◽  
Zhonglian Yang ◽  
Yongze Lu ◽  
Huang Shang ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Three Dimensional ◽  
Polluted Water ◽  
Bottom Surface ◽  
Zero Order Kinetics ◽  
Initial Ph ◽  
Water Effects ◽  
Effects Of Ph ◽  
Denitrifying Microorganisms ◽  
Denitrification Process

In this work, a three-dimensional bioelectrochemical reactor system (3D-BERs) with granular activated carbon (GAC) was utilized to study the feasibility of simultaneous removal of nitrates by autotrophic-heterotrophic denitrification process under different pH levels. In this present study, it was found that when the influent COD/ NO3--N ratio ranged between 1.5 and 3.5, both autotrophic and heterotrophic denitrifying microorganisms played an important role in denitrification. The experimental results demonstrated that the highest removal efficiency of nitrates under the optimum COD/NO3--N ratio of 1.5 (98.62%) was achieved with an initial pH of 7.5 ± 0.4. Likewise, when the COD/NO3--N ratio of 3.5, the nitrates removal efficiency (81.12%) was achieved with an initial pH of 8.2 ± 0.3, respectively. Batch denitrification processes followed zero-order kinetics at various NO3--N concentrations obtained. The bacterial community structure and relative abundance of bacteria changed at the level of genes and the phylum of immobilized GAC particles. Moreover, the diversity of bacterial composition enhanced the removal of NO3--N at the inner surface (IS), and bottom surface (BS) of immobilized GAC carriers were Gammaproteobacteria, Bacilli, Proteobacteria, and Thauera. In general, this technique is more effective for enhancing the denitrification process in the 3D-BER system.

scholarly journals Trimethoprim Antibiotic Adsorption from Aqueous Solution onto Eco-Friendly Zr-Metal Organic Framework Material

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7545
Author(s):  
Marwa Elkady ◽  
Kamal E. Diab ◽  
Hassan Shokry
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Metal Organic Framework ◽  
Physical Nature ◽  
Polluted Water ◽  
Solution Ph ◽  
X Ray ◽  
Adsorbent Dose

The synthesis of Bio-MOF using aspartic acid as an organic linker and water as a solvent was performed to create an environmentally friendly material. The chemical composition, structure, and morphology of the synthesized zirconium Bio-MOF (MIP-202) was evaluated using X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The synthesized Bio-MOF was used as an adsorbent for trimethoprim antibiotic as pollutants from an aqueous solution under various operating parameters. The increase in the initial trimethoprim concentration from 2.5 mg/L to 20 mg/L decreased the decontamination efficiency from 77.6% to 35.9% at a solution pH of 7 with 0.5 g/L adsorbent dose after 60 min reaction time. The rise of adsorbent dose from 0.1 g/L to 1.5 g/L increased the removal efficiency from 47.7% to 87.6%. The maximum trimethoprim removal efficiency of 95% was attained at a solution pH of 11. Langmuir and pseudo-second order models described the adsorption process of trimethoprim antibiotic onto zirconium Bio-MOF and the chemo-physical nature of trimethoprim adsorption onto the synthesized zirconium Bio-MOF. Accordingly, it was evident that the prepared zirconium Bio-MOF (MIP-202) is an ecofriendly and efficient adsorbent for antibiotic decontamination from polluted water.

Comparative Bio-sorption of Cadmium and Nickel Ions from Aqueous Solution onto Fibers of Date Palm using Fluidized Bed Column

2019 ◽  
Vol 70 (5) ◽  
pp. 1507-1512
Author(s):  
Baker M. Abod ◽  
Ramy Mohamed Jebir Al-Alawy ◽  
Firas Hashim Kamar ◽  
Gheorghe Nechifor
Keyword(s):  
Aqueous Solution ◽  
Heavy Metal ◽  
Metal Ions ◽  
Fluidized Bed ◽  
Removal Efficiency ◽  
Heavy Metal Ions ◽  
Date Palm ◽  
Operating Conditions ◽  
Initial Concentration ◽  
Bed Height

The aim of this study is to use the dry fibers of date palm as low-cost biosorbent for the removal of Cd(II), and Ni(II) ions from aqueous solution by fluidized bed column. The effects of many operating conditions such as superficial velocity, static bed height, and initial concentration on the removal efficiency of metal ions were investigated. FTIR analyses clarified that hydroxyl, amine and carboxyl groups could be very effective for bio-sorption of these heavy metal ions. SEM images showed that dry fibers of date palm have a high porosity and that metal ions can be trapped and sorbed into pores. The results show that a bed height of 6 cm, velocity of 1.1Umf and initial concentration for each heavy metal ions of 50 mg/L are most feasible and give high removal efficiency. The fluidized bed reactor was modeled using ideal plug flow and this model was solved numerically by utilizing the MATLAB software for fitting the measured breakthrough results. The breakthrough curves for metal ions gave the order of bio-sorption capacity as follow: Cd(II)]Ni(II).

Optimal operations for groundwater denitrification of drinking water using heterotrophic biological denitrification process

2006 ◽  
Vol 6 (2) ◽  
pp. 125-130
Author(s):  
C.-H. Hung ◽  
K.-H. Tsai ◽  
Y.-K. Su ◽  
C.-M. Liang ◽  
M.-H. Su ◽  
...  
Keyword(s):  
Drinking Water ◽  
Removal Efficiency ◽  
Nitrate Removal ◽  
Drinking Water Treatment ◽  
Nitrate Content ◽  
Source Water ◽  
Nitrogen Gas ◽  
Negative Effect ◽  
Denitrification Process ◽  
Heterotrophic Denitrification

Due to the extensive application of artificial nitrogen-based fertilizers on land, groundwater from the central part of Taiwan faces problems of increasing concentrations of nitrate, which were measured to be well above 30 mg/L all year round. For meeting the 10 mg/L nitrate standard, optimal operations for a heterotrophic denitrification pilot plant designed for drinking water treatment was investigated. Ethanol and phosphate were added for bacteria growing on anthracite to convert nitrate to nitrogen gas. Results showed that presence of high dissolved oxygen (around 4 mg/L) in the source water did not have a significantly negative effect on nitrogen removal. When operated under a C/N ratio of 1.88, which was recommended in the literature, nitrate removal efficiency was measured to be around 70%, sometimes up to 90%. However, the reactor often underwent severe clogging problems. When operated under C/N ratio of 1.0, denitrification efficiency decreased significantly to 30%. Finally, when operated under C/N ratio of 1.5, the nitrate content of the influent was almost completely reduced at the first one-third part of the bioreactor with an overall removal efficiency of 89–91%. Another advantage for operating with a C/N ratio of 1.5 is that only one-third of the biosolids was produced compared to a C/N value of 1.88.

Utilisation of Biomass and Hybrid Biochar from Elephant Grass and Low Density Polyethylene for the Competitive Adsorption of Pb(II), Cu(II), Fe(II) and Zn(II) from Aqueous Media

2020 ◽  
Vol 13 ◽  
Author(s):  
Joshua O. Ighalo ◽  
Lois T. Arowoyele ◽  
Samuel Ogunniyi ◽  
Comfort A. Adeyanju ◽  
Folasade M. Oladipo-Emmanuel ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Removal Efficiency ◽  
Contact Time ◽  
Competitive Adsorption ◽  
Adsorption Process ◽  
Aqueous Media ◽  
Polluted Water ◽  
Batch Adsorption ◽  
Order Kinetic ◽  
Elephant Grass

Background: The presence of pollutants in polluted water is not singularized hence pollutant species are constantly in competition for active sites during the adsorption process. A key advantage of competitive adsorption studies is that it informs on the adsorbent performance in real water treatment applications. Objective: This study aims to investigate the competitive adsorption of Pb(II), Cu(II), Fe(II) and Zn(II) using elephant grass (Pennisetum purpureum) biochar and hybrid biochar from LDPE. Method: The produced biochar was characterised by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The effect of adsorption parameters, equilibrium isotherm modelling and parametric studies were conducted based on data from the batch adsorption experiments. Results: For both adsorbents, the removal efficiency was >99% over the domain of the entire investigation for dosage and contact time suggesting that they are very efficient for removing multiple heavy metals from aqueous media. It was observed that removal efficiency was optimal at 2 g/l dosage and contact time of 20 minutes for both adsorbent types. The Elovich isotherm and the pseudo-second order kinetic models were best-fit for the competitive adsorption process. Conclusion: The study was able to successfully reveal that biomass biochar from elephant grass and hybrid biochar from LDPE can be used as effective adsorbent material for the removal of heavy metals from aqueous media. This study bears a positive implication for environmental protection and solid waste management.

Sign in / Sign up

Export Citation Format

Share Document