Degradation of reactive dyes by supercritical water oxidation in a batch reactor

Fulvic acid (FA) is a common refractory organic compound in landfill leachate. The degradation of FA in supercritical water oxidation (SCWO) was conducted in a SS 316 batch reactor. The effects of temperature, pressure, residence time, oxidation ratio and initial FA concentration on the degradation of FA were investigated. Results showed that FA could be easily destructed in SCWO process, and a total organic carbon (TOC) removal efficiency of 98.0% was available at 600 °C, 420 s, 25 MPa and 1% FA. Oxidation coefficient had a significant positive effect on the degradation of FA. Total carbon (TC) and TOC removal efficiencies increased from 78.9 % to 97.2 % and from 86.4 % to 97.2, respectively, when oxidation coefficient increased from 0 to 4. Benzene, phenol and naphthalene could be regarded as the intermediate products in SCWO.

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The Treatment of Concentrated Landfill Leachate from Membrane-Based Processes by Supercritical Water Oxidation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.522-524.560 ◽

2014 ◽

Vol 522-524 ◽

pp. 560-564 ◽

Cited By ~ 2

Author(s):

Yan Meng Gong ◽

Shu Zhong Wang ◽

Yan Hui Li

Keyword(s):

Residence Time ◽

Supercritical Water ◽

Landfill Leachate ◽

Water Oxidation ◽

Batch Reactor ◽

Oxygen Demand ◽

Ammonia Nitrogen ◽

Supercritical Water Oxidation ◽

N Removal ◽

Varied Temperature

Supercritical water oxidation (SCWO) of concentrated landfill leachate has been carried out in a batch reactor in fluidized bed sand bath, operated under varied temperature (450-600 °C), pressure (23-29 MPa), residence time (5-20 min) and oxidation coefficient (1.5-3.0). The experimental results indicated that temperature and oxidation coefficient had significant influences on the oxidation reaction, whereas the pressure and residence time were not crucial factors. The chemical oxygen demand (COD) and ammonia nitrogen (NH4-N) removal efficiencies could reach up to 99.23% and 98.64% at 600 °C, 25 MPa and 5 min with a oxidation coefficient of 2, respectively, and the effluents could be discharged harmlessly.

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Supercritical Water Oxidation of Lurgi Coal Gasification Wastewater and Evaluation of the Combined Process with Gasification

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.610-613.2203 ◽

2012 ◽

Vol 610-613 ◽

pp. 2203-2210 ◽

Cited By ~ 2

Author(s):

Yu Zhen Wang ◽

Shu Zhong Wang ◽

Yang Guo ◽

Dong Hai Xu ◽

Yan Meng Gong ◽

...

Keyword(s):

Supercritical Water ◽

Water Oxidation ◽

Coal Gasification ◽

Batch Reactor ◽

Supercritical Water Oxidation ◽

Combined Process ◽

Technical Feasibility ◽

Volatile Phenol ◽

Coal Gasification Wastewater ◽

Oxygen Ratio

Degradation of Lurgi coal gasification wastewater in supercritical water was investigated in a batch reactor, and a combined process of supercritical water oxidation (SCWO) and gasification was put forward to utilize the material and energy in SCWO effluent. The technical feasibility and economy were evaluated. In the SCWO process, when operated at condition of 500 °C, 25 MPa, oxygen ratio of 3.5 and residence time of 15 min, the concentrations of COD, NH3-N and volatile phenol in effluent reduced to 27, 11 and 0.4 mg/L, respectively, where the removal efficiencies were 99.81%, 99.85% and 99.99%, accordingly. The effluent could reach national discharge standard I (GB 8978-1996), and can be used as the gasification agents of gasifier via a pressure reducer. For a single Lurgi gasifier, the combied process could save 23 t/h of steam and 1550 kg/h of O2, which is equal to 4996 yuan/h.

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Kinetics Behavior and Sulfur Transformations of Iron Sulfide during Supercritical Water Oxiation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.524-527.1939 ◽

2012 ◽

Vol 524-527 ◽

pp. 1939-1942 ◽

Cited By ~ 5

Author(s):

Hong He Ma ◽

Shu Zhong Wang ◽

Lu Zhou

Keyword(s):

Activation Energy ◽

Supercritical Water ◽

Water Oxidation ◽

Iron Sulfide ◽

Reaction Pathway ◽

Batch Reactor ◽

Supercritical Water Oxidation ◽

Experimental Conditions ◽

Exponential Factor ◽

Gasification Process

Oxidation of iron sulfide in supercritical water was investigated in the batch reactor. Iron sulfide was converted in two parallel processes: gasification by water and oxidation by oxygen. Assuming that the reaction order of H2O was 0, the activation energy and pre-exponential factor of the gasification process were determined to be 43kJ mol-1 and 22.4 min-1, correspondingly. It is found that above 773K the oxidation process was limited by the mass transfer of O2 to particles surface. Below 773K, with an assumption of zero order in H2O concentration and first-order reaction in oxygen concentration, the activation energy and pre-exponential factor for the rate of oxidation were estimated as154kJ mol-1 and 1.7×106m3 mol-1 min-1, respectively. With supercritical water oxidation under the experimental conditions, the sulfur-containing components in the product were sulfide, sulfite and sulfate, in which sulfide and sulfate were predominant. It is likely to completely convert the sulfur to the sulfate by supercritical water oxidation using high temperature and long reaction time. The reaction pathway of iron sulfide could be expressed as: iron sulfide → sulfide → sulfite → sulfate.

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Treatment of Organic Phosphorus Pesticides Manufacturing Wastewater by Supercritical Water Oxidation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.788.434 ◽

2013 ◽

Vol 788 ◽

pp. 434-439 ◽

Cited By ~ 2

Author(s):

Xing Ying Tang ◽

Shu Zong Wang ◽

Li Li Qian ◽

Yan Hui Li

Keyword(s):

Response Surface Methodology ◽

Organic Acid ◽

Response Surface ◽

Supercritical Water ◽

Water Oxidation ◽

Influence Factor ◽

Organic Phosphorus ◽

Batch Reactor ◽

Polynomial Equation ◽

Supercritical Water Oxidation

Oxidation of organic phosphorus pesticides wastewater (OPPs-MW) was studied in a batch-reactor under the supercritical oxidizing water condition. The temperature, pressure and coefficient of oxidation were investigated as influence factor for COD removal efficiency by response surface methodology. Temperature is the most significant factor in treatment OPPs-MW and a good fitting polynomial equation obtained. Organic acid would generate under incomplete decomposition condition and NH3-N could hardly decompose effectively when temperature below 600°C

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