Advantages and disadvantages of different AOP
| Techniques . | Advantages . | Disadvantages . |
|---|---|---|
| Fe2+/Fe3+/H2O2 | Simple, low cost materials, production of strong oxidant, high efficiency, easy implementation in the industrial scale | Low regeneration rate of Fe2+, low pH requirement, high doses of reagents, sludge generation, parasitic reactions, difficulty in storage and transport of H2O2 |
| O3/H2O2 | Simple free radical production, high bactericide activity, less time consuming, high removal efficiencies | Low solubility of O3 in aqueous solutions, limited mass transfer, high cost of reagent, ineffectiveness at high pollutants concentrations, high energy consumption, short lifetime of UV lamps |
| WAO and CWAO | Mild operating conditions, small plant for operations, higher mineralization of pollutants, adapted with flow rates and effluent compositions, no production of secondary pollution | High capital cost, high energy consumption |
| H2O2/UV | Simple, cheap and sure source of radicals, high decomposition yield of H2O2, oxidation of a wide range of organic compounds, no sludge production | Difficulty in storage and transport of H2O2, short lifetime of UV lamps, low absorption coefficient of H2O2, lack of reactor design for UV illumination, generation of by-products |
| O3/ UV | Easy handling, relatively short reaction times, production of strong oxidant | Selectivity of molecular ozone, high operating cost, limited mass transfer, incomplete treatment of effluents, short lifetime of UV lamps, generation of by-products |
| H2O2/Fe2+ (Fe3+)/UV | High efficiency, equipment simplicity, no sludge production, an additional generation of radicals, possibility of coupling with solar energy | High operating cost, high energy consumption, short lifetime of UV lamps |
| H2O2/O3/UV | High hydroxyl radicals production, combines O3/H2O2 and UV/O3 systems, high removal efficiencies | High cost of reagent, high energy consumption, short lifetime of UV lamps |
| Fe3+/UV | High efficiency, no need for hydrogen peroxide addition, less expensive method in comparison with H2O2/Fe2+ (Fe3+)/UV and H2O2 /UV processes, no mass transfer limitation | Low pH requirement, high energy consumption, short lifetime and limited efficiency of UV lamps |
| TiO2/UV | Simple, available and low cost materials, operation at ambient conditions, wide pH range, oxidation of a wide range of organic compounds, possibility of coupling with solar energy | Formation of dark catalytic sludge, limited mass transfer, short lifetime and limited efficiency of UV lamps, difficulty in the recovery of the catalyst after treatment, difficulty of use on industrial scale |
| Sonochemical | Simple, environment friendly, ambient operating conditions, no production of toxic by-products | High capital cost, low OH• radical production, incomplete treatment of effluents |
| Electrochemical | Rapid, strong oxidation ability, lower temperature and pressure requirements, treatment of large volumes, no need for chemical reagents or large amounts of catalyst, low sludge production | High energy consumption, high operating cost, need for maintenance, need for high conductivity effluent |
| Techniques . | Advantages . | Disadvantages . |
|---|---|---|
| Fe2+/Fe3+/H2O2 | Simple, low cost materials, production of strong oxidant, high efficiency, easy implementation in the industrial scale | Low regeneration rate of Fe2+, low pH requirement, high doses of reagents, sludge generation, parasitic reactions, difficulty in storage and transport of H2O2 |
| O3/H2O2 | Simple free radical production, high bactericide activity, less time consuming, high removal efficiencies | Low solubility of O3 in aqueous solutions, limited mass transfer, high cost of reagent, ineffectiveness at high pollutants concentrations, high energy consumption, short lifetime of UV lamps |
| WAO and CWAO | Mild operating conditions, small plant for operations, higher mineralization of pollutants, adapted with flow rates and effluent compositions, no production of secondary pollution | High capital cost, high energy consumption |
| H2O2/UV | Simple, cheap and sure source of radicals, high decomposition yield of H2O2, oxidation of a wide range of organic compounds, no sludge production | Difficulty in storage and transport of H2O2, short lifetime of UV lamps, low absorption coefficient of H2O2, lack of reactor design for UV illumination, generation of by-products |
| O3/ UV | Easy handling, relatively short reaction times, production of strong oxidant | Selectivity of molecular ozone, high operating cost, limited mass transfer, incomplete treatment of effluents, short lifetime of UV lamps, generation of by-products |
| H2O2/Fe2+ (Fe3+)/UV | High efficiency, equipment simplicity, no sludge production, an additional generation of radicals, possibility of coupling with solar energy | High operating cost, high energy consumption, short lifetime of UV lamps |
| H2O2/O3/UV | High hydroxyl radicals production, combines O3/H2O2 and UV/O3 systems, high removal efficiencies | High cost of reagent, high energy consumption, short lifetime of UV lamps |
| Fe3+/UV | High efficiency, no need for hydrogen peroxide addition, less expensive method in comparison with H2O2/Fe2+ (Fe3+)/UV and H2O2 /UV processes, no mass transfer limitation | Low pH requirement, high energy consumption, short lifetime and limited efficiency of UV lamps |
| TiO2/UV | Simple, available and low cost materials, operation at ambient conditions, wide pH range, oxidation of a wide range of organic compounds, possibility of coupling with solar energy | Formation of dark catalytic sludge, limited mass transfer, short lifetime and limited efficiency of UV lamps, difficulty in the recovery of the catalyst after treatment, difficulty of use on industrial scale |
| Sonochemical | Simple, environment friendly, ambient operating conditions, no production of toxic by-products | High capital cost, low OH• radical production, incomplete treatment of effluents |
| Electrochemical | Rapid, strong oxidation ability, lower temperature and pressure requirements, treatment of large volumes, no need for chemical reagents or large amounts of catalyst, low sludge production | High energy consumption, high operating cost, need for maintenance, need for high conductivity effluent |