scholarly journals Supercritical water oxidation for the destruction of hazardous waste: better than incineration

2015 ◽  
Vol 373 (2057) ◽  
pp. 20150013 ◽  
Author(s):  
Bushra Al-Duri ◽  
Faihan Alsoqyani ◽  
Iain Kings
Keyword(s):  
Supercritical Water ◽  
Water Oxidation ◽  
Isopropyl Alcohol ◽  
Flow Reactor ◽  
Plug Flow ◽  
Reaction Medium ◽  
Supercritical Water Oxidation ◽  
Split Ratio ◽  
N Removal ◽  
Better Than

Supercritical water oxidation (SCWO) is an advanced process mainly employed for the treatment of hazardous stable wastes, otherwise treatable by incineration. It is based on the unique properties of water above its critical point ( T c =675 K, P c =22.2 MPa), making it a superior reaction medium for the destruction of all organics in the presence of oxygen. This work presents preliminary laboratory scale studies on SCWO of nitrogen (N)-containing hazardous hydrocarbons, with a view to enhancing the process performance, using available reagents and non-complex reactor design. This article investigates the destruction of dimethylformamide (DMF), carried out in a continuous (plug flow) reactor system. SCWO of DMF was enhanced by (i) a split-oxidant system, where stoichiometric oxidant was divided between two inlet ports at various ratios and (ii) the addition of isopropyl alcohol (IPA) as a co-fuel, premixed with the feedstock. Testing a range of temperatures, initial DMF concentrations, oxidant ratios, IPA ratios and oxidant split ratios, selected results were presented in terms of % total organic carbon and % N removal. Reaction kinetics were studied and showed a dramatic decrease in the activation energy upon adding IPA. Split-oxidant-feeding enhancement depended on the split ratio and secondary feed position.

An inclined plug-flow reactor design for supercritical water oxidation

2018 ◽  
Vol 343 ◽  
pp. 351-361 ◽  
Author(s):  
Zhong Chen ◽  
Hongzhen Chen ◽  
Xiaoling Liu ◽  
Chunlan He ◽  
Datian Yue ◽  
...  
Keyword(s):  
Supercritical Water ◽  
Water Oxidation ◽  
Flow Reactor ◽  
Plug Flow ◽  
Reactor Design ◽  
Plug Flow Reactor ◽  
Supercritical Water Oxidation

Supercritical water oxidation of quinoline in a continuous plug flow reactor—part 2: kinetics

2006 ◽  
Vol 81 (6) ◽  
pp. 919-926 ◽  
Author(s):  
Lisete DS Pinto ◽  
Luisa M Freitas dos Santos ◽  
Regina CD Santos ◽  
Bushra Al-Duri
Keyword(s):  
Supercritical Water ◽  
Water Oxidation ◽  
Flow Reactor ◽  
Plug Flow ◽  
Plug Flow Reactor ◽  
Supercritical Water Oxidation

Optimisation of the operation variables of a supercritical water oxidation process

2000 ◽  
Vol 42 (5-6) ◽  
pp. 107-113 ◽  
Author(s):  
M.J. Cocero ◽  
D. Vallelado ◽  
R. Torio ◽  
E. Alonso ◽  
F. Fdez-Polanco
Keyword(s):  
Organic Compounds ◽  
Removal Efficiency ◽  
Residence Time ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Isopropyl Alcohol ◽  
Reaction Medium ◽  
Supercritical Water Oxidation ◽  
Operation Conditions ◽  
Wide Range

The unique physical-chemical properties of water above its critical point (374.2°C and 22.1 MPa) makes supercritical water (SCW) an effective reaction medium for oxidation of organic compounds. Gases and many organic compounds are miscible in SCW, so reaction between oxygen and waste is carried out without interface transport constraints. Supercritical water oxidation (SCWO) can give high destruction efficiencies for a wide variety of hazardous wastes, at low reactor residence times. To study the SCWO, experiments were carried out in a pilot plant equipped with a pressure shell and cooled wall reactor. Effect of operation variables: oxidant excess, reaction temperature and residence time, is studied in order to optimise the contaminant removal efficiency. Aqueous solutions of isopropyl alcohol were used as feed. No effect of air excess and residence time higher than 1 minute on removal efficiency was found, so exclusive dependence of temperature is concluded. Whereas temperature is above 650°C, reactor can work in a wide range of operation conditions with destruction efficiency over 99%. In addition, operation at optimal conditions is reported, using 10%(w) isopropyl alcohol – 1%(w) aniline as feed. Removal efficiencies higher than 99.9% and nitrite-nitrate concentrations less than 10 ppm were obtained.

Kinetics of Ethylenediamine Wastewater Oxidation in Supercritical Water

2012 ◽  
Vol 531 ◽  
pp. 516-519 ◽  
Author(s):  
Jia Ming Zhang ◽  
Chun Yuan Ma
Keyword(s):  
Residence Time ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Flow Reactor ◽  
Plug Flow ◽  
Excess Oxygen ◽  
Supercritical Water Oxidation ◽  
Kinetics Equation ◽  
First Order ◽  
Kinetics Of

The decompositon of ethylenediamine (EDA) in supercritical water oxidation (SCWO) were investigated. The experiments were conducted in an isothermal and vertical continuous plug-flow reactor at 375-500°C, 25 MPa, residence time of 2-80 s, and excess oxygen of 150%. It was found that yields of nitrous oxide, nitrogen, and the denitrification rate increased as temperature and residence time increased. The kinetics for denitrification of EDA was described by a rate law involving first order reaction. The results calculated from kinetics equation reconciled the experimental data.

scholarly journals Supercritical Water Oxidation of 3-Methylpyridine with Propylene Glycol

2021 ◽  
Vol 33 (7) ◽  
pp. 1573-1578
Author(s):  
Falah Kareem Hadi Al-Kaabi ◽  
Bushra Al-Duri ◽  
Iain Kings
Keyword(s):  
Propylene Glycol ◽  
Removal Efficiency ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Isopropyl Alcohol ◽  
Flow Reactor ◽  
Hydroxyl Groups ◽  
Supercritical Water Oxidation ◽  
Toc Removal ◽  
Positive Effect

The destruction of 3-methylpyridine by supercritical water oxidation (SCWO) using propylene glycol (PG) and isopropyl alcohol (IPA) as co-fuels in a plug flow reactor was carried out. Hydrogen peroxide was the oxygen source. All the experiments were carried out at 25 MPa and a range of temperatures from 425-525 ºC. The residence times range from 6 s to 14 s. Results were presented in terms of total organic carbon (TOC) as a function of time with various process parameters. The findings support the positive effect that propylene glycol has on the destruction of 3-methylpyridine, where TOC removal is ≥ 97.5% at 525 ºC and 14 s. The maximum TOC removal efficiency is 93% at 425 ºC, 14 s, and the [propylene glycol]/[3-methylpyridine]o ratio of 3. The removal efficiency of nitrogen in the presence of propylene glycol reaches 89% at 525 ºC and 10 s. The oxidant ratio also has a positive effect on the removal of TOC in the three systems. Addition of propylene glycol causes a significant development in the ratio at 425 ºC, more so than when isopropyl alcohol was added. This is due to two hydroxyl groups in propylene glycol oxidation that enhance the reaction by generating various free radicals.

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

2014 ◽  
Vol 522-524 ◽  
pp. 560-564 ◽  
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.

Treatability of Phenol by Supercritical Water Oxidation

2011 ◽  
Vol 422 ◽  
pp. 462-465
Author(s):  
Hui Li ◽  
En Zhao
Keyword(s):  
Supercritical Water ◽  
Water Oxidation ◽  
Continuous Flow ◽  
Flow Reactor ◽  
Reaction Times ◽  
Supercritical Water Oxidation ◽  
Continuous Flow Reactor ◽  
Organic Destruction ◽  
Water Conditions ◽  
Phenol Wastewater

This study focused on the treatment of phenol wastewater by supercritical water oxidation(SCWO). Tests were conducted by using a continuous-flow reactor system. Based on COD, organic destruction efficiencies of phenol wastewater were obtained at supercritical water conditions. Temperatures and pressures, respectively, ranged from 400-500°C,and 25-40Mpa. The reaction times varied from 30 to 190 seconds, and hydrogen peroxide was used as oxidant. Under SCWO conditions, destruction efficiencies greater than 99% were achieved.

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