The Removal of Binary Mixture of Dyes by Heterogeneous Fenton Oxidation: Kinetics, Product Identification and Toxicity Assessment

The removal of mixture of two azo dyes, Acid blue 29 and Ponceau xylidine, was studied by heterogeneous Fenton and Fenton-type processes using hydrogen peroxide and sodium persulphate as oxidants in the presence of and nano and micro-Fe2O3 particles as catalysts. The synthesised nano-Fe2O3 particles were characterised using analytical techniques viz. FT-IR, TEM, EDX, powder XRD and VSM. We have examined the effects of particle size on the COD removal efficiency and the reusability of the catalyst after optimising pH, and concentrations of catalyst and oxidant. Combination of nano-Fe2O3 and hydrogen peroxide possessed higher COD removal efficiency, which was accelerated in acidic pH and inhibited at pH > 6. Total consumption of hydrogen peroxide confirmed the efficiency of the optimised parameters. The mechanism of the formation of intermediate ions and products are proposed. COD removal and consumption of hydrogen peroxide follow pseudo-first-order kinetics. The toxicity of the solutions was assessed using Aliivibrio fischeri light loss and Escherichia coli growth inhibition assays. Both the assays showed different toxicity levels for the same solution.

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Investigation of Heavy Metal Effects on the Anaerobic Co-Digestion Process of Waste Activated Sludge and Septic Tank Sludge

International Journal of Chemical Engineering ◽

10.1155/2019/5138060 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9

Author(s):

Quang-Minh Nguyen ◽

Duy-Cam Bui ◽

Thao Phuong ◽

Van-Huong Doan ◽

Thi-Nham Nguyen ◽

...

Keyword(s):

Heavy Metals ◽

Heavy Metal ◽

Activated Sludge ◽

Removal Efficiency ◽

Biogas Production ◽

Cod Removal ◽

Septic Tank ◽

Waste Activated Sludge ◽

Digestion Process ◽

Cod Removal Efficiency

The effect of copper, zinc, chromium, and lead on the anaerobic co-digestion of waste activated sludge and septic tank sludge in Hanoi was studied in the fermentation tests by investigating the substrate degradation, biogas production, and process stability at the mesophilic fermentation. The tested heavy metals were in a range of concentrations between 19 and 80 ppm. After the anaerobic tests, the TS, VS, and COD removal efficiency was 4.12%, 9.01%, and 23.78% for the Cu(II) added sample. Similarly, the efficiencies of the Zn(II) sample were 1.71%, 13.87%, and 16.1% and Cr(VI) efficiencies were 15.28%, 6.6%, and 18.65%, while the TS, VS, and COD removal efficiency of the Pb(II) added sample was recorded at 16.1%, 17.66%, and 16.03% at the concentration of 80 ppm, respectively. Therefore, the biogas yield also decreased by 36.33%, 31.64%, 31.64%, and 30.60% for Cu(II), Zn(II), Cr(VI), and Pb(II) at the concentration of 80 ppm, compared to the raw sample, respectively. These results indicated that Cu(II) had more inhibiting effect on the anaerobic digestion of the sludge mixture than Zn(II), Cr(VI), and Pb(II). The relative toxicity of these heavy metals to the co-digestion process was as follows: Cu (the most toxic) > Zn > Cr > Pb (the least toxic). The anaerobic co-digestion process was inhibited at high heavy metal concentration, which resulted in decreased removal of organic substances and produced biogas.

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Combined treatment of hydroxypropyl guar gum in oilfield fracturing wastewater by coagulation and the UV/H2O2/ferrioxalate complexes process

Water Science & Technology ◽

10.2166/wst.2017.552 ◽

2017 ◽

Vol 77 (3) ◽

pp. 565-575 ◽

Cited By ~ 3

Author(s):

Zhenchao Zhang

Keyword(s):

Removal Efficiency ◽

Guar Gum ◽

Combined Treatment ◽

Cod Removal ◽

Treated Wastewater ◽

Spectra Analysis ◽

Hydroxypropyl Guar ◽

Coagulation Process ◽

Cod Removal Efficiency ◽

Hydroxypropyl Guar Gum

Abstract Hydroxypropyl guar gum is considered to be a main component of oilfield fracturing wastewater (OFW). This work is intended to optimize the experimental conditions for the maximum oxidative degradation of hydroxypropyl guar gum by the coagulation and UV/H2O2/ferrioxalate complexes process. Optimal reaction conditions were proposed based on the chemical oxygen demand (COD) removal efficiency and UV_vis spectra analysis. The overall removal efficiency of COD reached 83.8% for a dilution ratio of raw wastewater of 1:2, pH of 4 and FeCl3 loading of 1,000 mg/L in the coagulation process; the dosage of H2O2 (30%,v/v) was 0.6% (v/v) and added in three steps, the n(H2O2)/n(Fe2+) was 2:1, n(Fe2+)/n(C2O42−) was 3:1 and pH was 4 in the UV/H2O2/ferrioxalate complexes process; pH was adjusted to 8.5–9 by NaOH and then cationic polyacrylamide (CPAM) of 2 mg/L was added in the neutralization and flocculation process. The decrease in COD during the coagulation process reduced the required H2O2 dosage and improved efficiency in the subsequent UV/H2O2/ferrioxalate complexes process. Furthermore, COD removal efficiency significantly increased by more than 13.4% with the introduction of oxalate compared with UV/Fenton. The UV_vis spectra analysis results indicated that the coagulation and UV/H2O2/ferrioxalate complexes process could efficiently remove the hydroxypropyl guar gum dissolved in OFW. An optimal combination of these parameters produced treated wastewater that met the GB8978-1996 Integrated Wastewater Discharge Standard level III emission standard.

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Textile Wastewater Treatment Using Combined Process of Biological Wriggle Bed and Ozone Biological Aerated Filter

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.441.589 ◽

2012 ◽

Vol 441 ◽

pp. 589-592

Author(s):

Zhi Min Fu ◽

Yu Gao Zhang ◽

Xiao Jun Wang

Keyword(s):

Wastewater Treatment ◽

Removal Efficiency ◽

Textile Wastewater ◽

Cod Removal ◽

Biological Aerated Filter ◽

Combined Process ◽

Cod Removal Efficiency ◽

Aerated Filter ◽

Textile Wastewater Treatment

A combined process of biological wriggle bed and ozone biological aerated filter was utilized to treat textile wastewater. Results showed that COD removal efficiency was almost 90.4%. The average effluent COD was 85.87 mg/L. The effluent colority was 64-32 times. This study indicated that the combined process is potentially useful for treating textile wastewater.

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Electrocoagulation and nanofiltration integrated process application in purification of bilge water using response surface methodology

Water Science & Technology ◽

10.2166/wst.2016.168 ◽

2016 ◽

Vol 74 (3) ◽

pp. 564-579 ◽

Cited By ~ 11

Author(s):

Ceyhun Akarsu ◽

Yasin Ozay ◽

Nadir Dizge ◽

H. Elif Gulsen ◽

Hasan Ates ◽

...

Keyword(s):

Response Surface Methodology ◽

Response Surface ◽

Removal Efficiency ◽

Cod Removal ◽

Positive Sign ◽

Aluminum Electrode ◽

Integrated Process ◽

Bilge Water ◽

Cod Removal Efficiency ◽

Initial Ph

Marine pollution has been considered an increasing problem because of the increase in sea transportation day by day. Therefore, a large volume of bilge water which contains petroleum, oil and hydrocarbons in high concentrations is generated from all types of ships. In this study, treatment of bilge water by electrocoagulation/electroflotation and nanofiltration integrated process is investigated as a function of voltage, time, and initial pH with aluminum electrode as both anode and cathode. Moreover, a commercial NF270 flat-sheet membrane was also used for further purification. Box–Behnken design combined with response surface methodology was used to study the response pattern and determine the optimum conditions for maximum chemical oxygen demand (COD) removal and minimum metal ion contents of bilge water. Three independent variables, namely voltage (5–15 V), initial pH (4.5–8.0) and time (30–90 min) were transformed to coded values. The COD removal percent, UV absorbance at 254 nm, pH value (after treatment), and concentration of metal ions (Ti, As, Cu, Cr, Zn, Sr, Mo) were obtained as responses. Analysis of variance results showed that all the models were significant except for Zn (P > 0.05), because the calculated F values for these models were less than the critical F value for the considered probability (P = 0.05). The obtained R2 and Radj2 values signified the correlation between the experimental data and predicted responses: except for the model of Zn concentration after treatment, the high R2 values showed the goodness of fit of the model. While the increase in the applied voltage showed negative effects, the increases in time and pH showed a positive effect on COD removal efficiency; also the most effective linear term was found as time. A positive sign of the interactive coefficients of the voltage–time and pH–time systems indicated synergistic effect on COD removal efficiency, whereas interaction between voltage and pH showed an antagonistic effect.

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Impact of Precipitants on the Structure and Properties of Fe-Co-Ce Composite Catalysts

Journal of Nanomaterials ◽

10.1155/2016/3797896 ◽

2016 ◽

Vol 2016 ◽

pp. 1-8

Author(s):

Yongli Zhang ◽

Shujuan Dai ◽

Yanbo Zhou ◽

Kai Lin

Keyword(s):

Particle Size ◽

Methyl Orange ◽

Removal Efficiency ◽

Cod Removal ◽

Catalytic Wet Air Oxidation ◽

Structure And Properties ◽

Air Oxidation ◽

Wet Air Oxidation ◽

Composite Catalysts ◽

Cod Removal Efficiency

Fe-Co-Ce composite catalysts were prepared by coprecipitation method using CO(NH2)2, NaOH, NH4HCO3, and NH3·H2O as precipitant agents. The effects of the precipitant agents on the physicochemical properties of the Fe-Co-Ce based catalysts were investigated by SEM, TEM, BET, TG-DTA, and XRD. It was found that the precipitant agents remarkably influenced the morphology and particle size of the catalysts and affected the COD removal efficiency, decolorization rate, and pH of methyl orange for catalytic wet air oxidation (CWAO). The specific surface area of the Fe-Co-Ce composite catalysts successively decreased in the order of NH3·H2O, NH4HCO3, NaOH, and CO(NH2)2, which correlated to an increasing particle size that increased for each catalyst. For the CWAO of a methyl orange aqueous solutions, the effects of precipitant agents NH3·H2O and NaOH were superior to those of CO(NH2)2and NH4HCO3. The catalyst prepared using NH3·H2O as the precipitant agent was mostly composed of Fe2O3, CoO, and CeO2. The COD removal efficiency of methyl orange aqueous solution for NH3·H2O reached 92.9% in the catalytic wet air oxidation. Such a catalytic property was maintained for six runs.

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Development of a two-stage flexible fibre biofilm reactor for treatment of food processing wastewater

Water Science & Technology ◽

10.2166/wst.2003.0604 ◽

2003 ◽

Vol 47 (11) ◽

pp. 189-194 ◽

Cited By ~ 6

Author(s):

Q.J. Yu ◽

H. Xu ◽

D. Yao ◽

P. Williams

Keyword(s):

Removal Efficiency ◽

Food Processing ◽

Cost Effective ◽

Biofilm Reactor ◽

Cod Removal ◽

Two Stage ◽

Cod Removal Efficiency ◽

Cost Effective Treatment ◽

Removal Efficiencies ◽

Food Processing Wastewater

Biofilm (or attached growth) reactors can be effectively used to treat organic wastewater from various industries such as food processing industry. They have a number of advantages including high organic loading rates (OLRs) and improved operational stability. A flexible fibre biofim reactor (FFBR) has been developed for efficient and cost effective treatment of food processing wastewater. In the process, simple flexible fibre packing with a very high specific surface area is used as support for microorganisms. The COD removal efficiencies for a range of OLRs have been studied. The FFBR can support an increasingly high OLR, but with a corresponding decrease in the COD removal efficiency. Therefore, a two-stage FFBR was developed to increase the treatment efficiency for systems with high OLRs. Experimental results indicated that a high overall COD removal efficiency could be achieved. At an influent COD of about 2700 mg/L and an OLR of 7.7 kgCOD/m3d, COD removal efficiencies of 76% and 82% were achieved in the first and the second stage of the reactor, respectively. The overall COD removal efficiency was 96%. Therefore, even for wastewater samples with high organic strength, high quality treated effluents could be readily achieved by the use of multiple stage FFBRs.

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Treatment of oilfield wastewater by combined process of micro-electrolysis, Fenton oxidation and coagulation

Water Science & Technology ◽

10.2166/wst.2017.486 ◽

2017 ◽

Vol 76 (12) ◽

pp. 3278-3288 ◽

Cited By ~ 3

Author(s):

Zhenchao Zhang

Keyword(s):

Reaction Time ◽

Removal Efficiency ◽

Treatment Process ◽

Cod Removal ◽

Fenton Oxidation ◽

Oily Wastewater ◽

Optimum Conditions ◽

Combined Process ◽

Cod Removal Efficiency ◽

Optimized Conditions

Abstract In this study, a combined process was developed that included micro-electrolysis, Fenton oxidation and coagulation to treat oilfield fracturing wastewater. Micro-electrolysis and Fenton oxidation were applied to reduce chemical oxygen demand (COD) organic load and to enhance organic components gradability, respectively. Orthogonal experiment were employed to investigate the influence factors of micro-electrolysis and Fenton oxidation on COD removal efficiency. For micro-electrolysis, the optimum conditions were: pH, 3; iron-carbon dosage, 50 mg/L; mass ratio of iron-carbon, 2:3; reaction time, 60 min. For Fenton oxidation, a total reaction time of 90 min, a H2O2 dosage of 12 mg/L, with a H2O2/Fe2+ mole ratio of 30, pH of 3 were selected to achieve optimum oxidation. The optimum conditions in coagulation process: pH, cationic polyacrylamide dosage, mixing speed and time is 4.3, 2 mg/L, 150 rpm and 30 s, respectively. In the continuous treatment process under optimized conditions, the COD of oily wastewater fell 56.95%, 46.23%, 30.67%, respectively, from last stage and the total COD removal efficiency reached 83.94% (from 4,314 to 693 mg/L). In the overall treatment process under optimized conditions, the COD of oily wastewater was reduced from 4,314 to 637 mg/L, and the COD removal efficiency reached 85.23%. The contribution of each stage is 68.45% (micro-electrolysis), 24.07% (Fenton oxidation), 7.48% (coagulation), respectively. Micro-electrolysis is the uppermost influencing process on COD removal. Compared with the COD removal efficiency of three processes on raw wastewater under optimized conditions: the COD removal efficiency of single micro-electrolysis, single Fenton oxidation, single coagulation is 58.34%, 44.88% and 39.72%, respectively. Experiments proved the effect of combined process is marvelous and the overall water quality of the final effluent could meet the class III national wastewater discharge standard of petrochemical industry of China (GB8978-1996).

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Combined organic carbon and complete nitrogen removal using anaerobic and aerobic upflow filters

Water Science & Technology ◽

10.2166/wst.1994.0629 ◽

1994 ◽

Vol 30 (12) ◽

pp. 297-306 ◽

Cited By ~ 31

Author(s):

Joseph Akunna ◽

Claude Bizeau ◽

René Moletta ◽

Nicolas Bernet ◽

Alain Héduit

Keyword(s):

Organic Carbon ◽

Removal Efficiency ◽

Nitrogen Removal ◽

Nitrogen Loss ◽

Ammonia Nitrogen ◽

Cod Removal ◽

Cod Removal Efficiency ◽

Treated Effluent ◽

Treated Effluents ◽

Aerobic And Anaerobic

Two laboratory upflow aerobic and anaerobic filters fed with synthetic wastewaters were used to study firstly the effects of aeration rate on the nitrification of anaerobically pre-treated effluents and secondly the effects of recycle-to-influent ratios on methane production rate, denitrification and nitrification performances of a combined aerobic and anaerobic wastewater treatment process. Nitrification of anaerobically pre-treated effluent was accompanied by aerobic post-treatment for residual COD removal. A comparison of nitrification performances using autotrophic medium and anaerobically pre-treated effluents (containing 1203 mg COD 1−1) with the same ammonia nitrogen concentration of about 300 mg NH4-N 1−1 showed that 3% of added ammonia nitrogen was assimilated by autotrophic nitrifiers during nitrification of the autotrophic medium while up to 30% was assimilated by both nitrifiers and heterotrophs during organic carbon removal and nitrification of anaerobically pre-treated effluent. Furthermore, it was suspected that significant nitrogen loss through denitrification occured in the aerobic filter especially at low aeration rates. In the study of the combined aerobic-anaerobic system, maximum ammonia nitrogen removal of 70% through denitrification was obtained at recycle-to-influent ratios of 4 and 5. COD removal efficiency in the anaerobic filter decreased from 77 to 60% for recycle-to-influent ratios of zero to 5. Overall COD removal efficiency of the entire system was constant at about 99% due to heterotrophic COD removal in the aerobic filter.

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COD removal efficiency and mechanism of HMBR in high volumetric loading for ship domestic sewage treatment

Water Science & Technology ◽

10.2166/wst.2016.271 ◽

2016 ◽

Vol 74 (7) ◽

pp. 1509-1517 ◽

Cited By ~ 4

Author(s):

Linan Zhu ◽

Hailing He ◽

Chunli Wang

Keyword(s):

Removal Efficiency ◽

Removal Rate ◽

Sewage Treatment ◽

Oxygen Demand ◽

Domestic Sewage ◽

Cod Removal ◽

Aeration Tank ◽

Remarkable Effect ◽

Cod Removal Efficiency ◽

Volumetric Loading

The hybrid membrane bioreactor (HMBR) has been applied in ship domestic sewage treatment under high volumetric loading for ship space saving. The mechanism and influence factors on the efficiency, including hydraulic retention time (HRT), dissolved oxygen (DO) of chemical oxygen demand (COD) removal were investigated. The HMBR's average COD removal rate was up to 95.13% on volumetric loading of 2.4 kgCOD/(m3•d) and the COD concentration in the effluent was 48.5 mg/L, far below the International Maritime Organization (IMO) discharge standard of 125 mg/L. DO had a more remarkable effect on the COD removal efficiency than HRT. In addition, HMBR revealed an excellent capability of resisting organics loading impact. Within the range of volumetric loading of 0.72 to 4.8 kg COD/(m3•d), the effluent COD concentration satisfied the discharge requirement of IMO. It was found that the organics degradation in the aeration tank followed the first-order reaction, with obtained kinetic parameters of vmax (2.79 d−1) and Ks (395 mg/L). The original finding of this study had shown the effectiveness of HMBR in organic contaminant degradation at high substrate concentration, which can be used as guidance in the full scale of the design, operation and maintenance of ship domestic sewage treatment devices.

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Treatment of simulated printing and dyeing wastewater using ozone microbubble

E3S Web of Conferences ◽

10.1051/e3sconf/202126104005 ◽

2021 ◽

Vol 261 ◽

pp. 04005

Author(s):

Emmanuel Nkudede ◽

Husseini Sulemana ◽

Bo Zhang ◽

Kaida Zhu ◽

Shan Hu ◽

...

Keyword(s):

Mass Transfer ◽

Methylene Blue ◽

Removal Efficiency ◽

Human Life ◽

Cod Removal ◽

Dyeing Wastewater ◽

Flow Rates ◽

Printing And Dyeing Wastewater ◽

Cod Removal Efficiency ◽

Initial Ph

Owing to its widespread and persistent usage, methylene blue (MB) is an environmental substance, mostly found in the printing and dyeing industry that raises concerns in the environment recently by posing significant threat to human life and the ecosystem as a whole. Thus, there is the need to effectively manage and treat the wastewater from these industries before reaching to the available water sources. Ozonation treatment is very efficient in treating printing and dyeing wastewater (MB) and can be greatly improved by using micro-bubble technology. Microbubble dissolution is an effective way to improve the rate of ozone mass transfer. To discover these properties, a method was used to improve the mass transfer of ozone microbubbles, which was used to effectively treat simulated printing and dyeing wastewater. We investigated the effects of pH, water temperature, ozone flow, and other conditions on the dissolution and attenuation properties of ozone in methylene blue microbubble solutions. Treatment of simulated printing and dyeing wastewater (methylene blue) was investigated under various initial pH and ozone flow rates. A catalytic exhibition was performed towards the decolorization of methylene blue (MB) concentrations and the corresponding COD removal efficiency. Ozone depletion and pH levels played key roles in MB degradation. Under high pH level of 11.01, the rate of removal of COD was 93.5%. Ozone dosage also has direct effect on COD removal efficiency and decolorization. Higher ozone flow rates, 0.4 L/min and 0.5 L/min recorded more than 94% degradation of COD thus very effective and efficient. Also, ozone flow rates 0.3 L/min, 0.4 L/min and 0.5 L/min with initial pH, 7.03, 6.63 and 6.36 decreased to 3.43, 3.49 and 3.44 after reaction processes which clearly shows that with high ozone dosage, pH reduces considerably.

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