Chemical oxidation Reactants Products Reduced Oxidized Oxidants Reductants electrons electron acceptors donors Definition: Oxidation reactions are viewed as reactions involving the exchange of electrons. TVM 4145 Vannrenseprosesser TorOve Leiknes

Oxidation in water treatment: 1. Oxidation of reduced inorganic species Fe(II), Mn(II), S(-II), As(III) 2. Oxidation of organic compounds color removal (NOM) hazardous synthetic compounds (i.e. TCE, atrazine) destroy taste- and odor-causing compounds 3. Biocidal effects of oxidation disinfection control aquatic growth, biofilms, algae etc. TVM 4145 Vannrenseprosesser TorOve Leiknes

Oxidants used in water treatment fluorine (f) chlorine (Cl) bromine (Br) iodine (I) Halogens: Chlorine most used chloramines ozone (O3) hydrogen peroxide (H2O2) Fenton’s reagent (H2O2/Fe2+) potassium permanganate (KMnO4) Oxidizing agents: Advanced Oxidation Processes (AOP): hydroxyl radicals (OH●) Combining oxidizing agents, UV, catalysts etc. TVM 4145 Vannrenseprosesser TorOve Leiknes

Removal of reduced inorganic species: soluble insoluble Fe/Mn: reduced form oxidized form Oxidants: oxygen, ozone, permanganate, chlorine Fe: Kinetics: rapid at pH > 7 1.order on Fe and O2 2.order on OH non-complexed forms TVM 4145 Vannrenseprosesser TorOve Leiknes

Mn: Oxidation with oxygen Kinetics: at pH > 9 slow with O2 alternative oxidants Oxidation with permanganate Potassium permanganate: 2. Green sand: TVM 4145 Vannrenseprosesser TorOve Leiknes

Removal of organic compounds Oxidation attacks the carbon-carbon double bonds and splits the long molecular chain into smaller compounds NOM: formation of by products complete oxidation → CO2 biodegradable compounds formation of halogenated species Synthetic organic compounds: dependent on compound competition of other constituents dependent on pH and temperature formation of halogenated species TVM 4145 Vannrenseprosesser TorOve Leiknes