advanced oxidation processes for wastewater...
TRANSCRIPT
Advanced Oxidation Processes for Wastewater Treatment
Beate GüntherInstitute for Geo ScienceJohannes Gutenberg University MainzTutor: Prof. Dr. R.-D. Wilken
Introduction
Oxidation-Reduction-ReactionTransfer of electrons (loss, gain)
Chemical Oxidation Main aim: Mineralization of organic compounds intoCO2 , H2O and harmless inorganic products
Oxidizing AgentEffects the oxidation of a substanceGets reduced
Quelle: DVGW Lehr-und Handbuch der Wasserversorgung Bd. 6 (2004) S.316
OH-radicale
Ozon
Hydrogen Peroxid
Permanganat
Oxygen
The higher the Redox-Potential, the higher the Oxidation-Power
Oxidizing Agents
Advanced Oxidation Processes (AOP) -Characteristics
same chemical feature: Production of OH-Radicals
Very reactive speciesAttack the most part of organic molecules Little selectivity of attack useful for an oxidant used in wastewater treatment
Work under ambient Conditions
AOP´s different reacting Systems e.g. :
Fenton-/Fenton-like Reactions, Ozone-Water-UV Systems, electrochemical OxidationDifferent combinations
Fenton Reaction
Producing OH radicals by means of addition of H2O2 to Fe²+ salts
Easy way to produce OH-RadicalFe non toxic, abundantNo special instrumentspH dependent (2,7-2,8)Neutralization - Flocks, Sludge (disposal problems)
Ozon-Water-System O3/H2O2 H2O2/UV O3/UV
O3 higher absorption yield than H2O2H2O2 is effective at wave lengths < 254nmSpecial instrumentsOzone generation is expensive
proaquaComparision of some AOP - Example
pH 3 u. 10 UV/O3 pH ?? UV/ H2O2 / Fe²+
Points to consider for O3/H2O2 - H2O2/UV - O3/UV
Influence of pHOH-Radical ScavengerLight wastingMass transfer limitationAdditional equipmentsCost evaluation
Capital costs, operating costs, maintenanceDepends on the nature and concentration of the pollutants, flow rate, reactor configuration
Boron Doped Diamond – Elektrode (EAOP)
•Covered with thin layer Diamond •Doped with Boron – make conductive•Bears a high over voltage (Material)•Generation of OH-Radicals direct from water
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BDD-Electrode
CSB-Abbau
0
200
400
600
800
1000
1200
0 50 100 150 200 250 300
Zeit t (min)
CSB
(mg/
l) I = 1,36 A
Nach Modell
bei I= 3,03
Material does not expendNo chemicals Water needs just a conductivityDegradation depends on current densityOptimal current density – depends on CODEasy to handleExpensive to produce
ConclusionsAOP´s high application
Drinking waterWaste waterIndustrial wastewaterSoil
Pretreatment for biological treatment
High potential (research)
Efficiency depends on character and concentration of pollutions
ReferencesS. Parsons Advanced oxidation processes for water and wastewater treatment, IWA Publishing(2004)
P. Bautista et al. Review: An overview of the application of Fenton oxidation to industrialwastewaters treatment, Journal of Chemical Biotechnology 83 (2008) 1323-1338
Ruppert UV/O3, UV/H2O2, UV/TiO2 and the Photo-Fenton Reaction Comparison of AdvancedOxidation Processes for Wastewater Treatment, Cosmosphere 28 (1994) 1147-1454
W.H. Glaze et al. The chemistry of water treatment processes involving ozone, hydrogen peroxideand ultraviolet radiation, Ozone Sci. Eng. 9 (1987) 335
R. Andreozzi et al. Advanced oxidation processes (AOP) for water purification and recovery, Catalysis Today 53 (1999) 51-59
C. Höfl et al. Oxidative degradation of AOX and COD by different advanced oxidation processes: A comparative study with two samples of pharmaceutical wastewater, Wat. Sci. Tech. Vol. 35 (1997) 257-264
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