Advanced Oxidation Process
Encyclopedia
Advanced oxidation processes (abbreviation: AOPs)refers to a set of chemical treatment procedures designed to remove organic and inorganic materials in waste water by oxidation. One such type of process is called in situ chemical oxidation.
Contaminants are oxidized by four different reagents: ozone
, hydrogen peroxide
, oxygen
, and air, in precise, pre-programmed dosages, sequences, and combinations. These procedures may also be combined with UV
irradiation and specific catalysts. This results in the development of hydroxyl radicals. A well known example of AOP is the use of Fenton's reagent
.
The AOP procedure is particularly useful for cleaning biologically toxic or non-degradable materials such as aromatics, pesticides, petroleum
constituents, and volatile organic compound
s in waste water . The contaminant materials are converted to a large extent into stable inorganic compounds such as water
, carbon dioxide
and salts, i.e. they undergo mineralization
. A goal of the waste water purification by means of AOP procedures is the reduction of the chemical contaminants and the toxicity to such an extent that the cleaned waste water may be reintroduced into receiving streams or, at least, into a conventional sewage treatment
.
Contaminants are oxidized by four different reagents: ozone
Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...
, hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...
, oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
, and air, in precise, pre-programmed dosages, sequences, and combinations. These procedures may also be combined with UV
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
irradiation and specific catalysts. This results in the development of hydroxyl radicals. A well known example of AOP is the use of Fenton's reagent
Fenton's reagent
Fenton's reagent is a solution of hydrogen peroxide and an iron catalyst that is used to oxidize contaminants or waste waters. Fenton's reagent can be used to destroy organic compounds such as trichloroethylene and tetrachloroethylene ....
.
The AOP procedure is particularly useful for cleaning biologically toxic or non-degradable materials such as aromatics, pesticides, petroleum
Petroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...
constituents, and volatile organic compound
Volatile organic compound
Volatile organic compounds are organic chemicals that have a high vapor pressure at ordinary, room-temperature conditions. Their high vapor pressure results from a low boiling point, which causes large numbers of molecules to evaporate or sublimate from the liquid or solid form of the compound and...
s in waste water . The contaminant materials are converted to a large extent into stable inorganic compounds such as water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
, carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
and salts, i.e. they undergo mineralization
Mineralization
Mineralization may refer to:* Mineralization , the process through which an organic substance becomes impregnated by inorganic substances...
. A goal of the waste water purification by means of AOP procedures is the reduction of the chemical contaminants and the toxicity to such an extent that the cleaned waste water may be reintroduced into receiving streams or, at least, into a conventional sewage treatment
Sewage treatment
Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants...
.
See also
- Waste water treatment
- Sewage treatmentSewage treatmentSewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants...
- Water purificationWater purificationWater purification is the process of removing undesirable chemicals, materials, and biological contaminants from contaminated water. The goal is to produce water fit for a specific purpose...
- Process engineeringProcess engineeringProcess engineering focuses on the design, operation, control, and optimization of chemical, physical, and biological processes through the aid of systematic computer-based methods...