EnviroChemie advanced oxidation processes for water treatment

Water treatment specialist EnviroChemie has developed a range of advanced oxidation processes (AOPs) for treating water and wastewater. These Envochem® AOP chemico-physical solutions remove the residues of active pharmaceutical ingredients (APIs) or endocrine disruptor chemicals (EDCs) from wastewater.

Advanced oxidation processes for water treatment

Advanced oxidation processes (AOPs) are chemical treatment procedures that use oxidizing reactions with OH hydroxyl radicals to remove organic and some inorganic materials from water and wastewater.

Highly reactive and short-lived hydroxyl radicals play an important role in radical and atmospheric chemistry. Since the late 1870s, Fenton chemistry has relied on hydroxyl radicals produced during UV-light dissociation of supplied with a capacity up to 100 m³/d. supplied with a capacity up to 100 m³/d. to catalyze peroxide-mediated oxidations of organic compounds.

Oxidation processes involving OH were initially highlighted for water treatment in the late 1980s, coining the term “Advanced Oxidation Processes”. AOPs are still specialized technology but are becoming increasingly widely adopted for tertiary water treatment to eliminate the most persistent and problematic organic and inorganic contaminants.

Increasing need for water recycling and more stringent environmental regulations are currently accelerating the uptake of AOPs worldwide, especially in the pharmaceutical and chemical industries.

Normally the term ‘advanced oxidation’ refers specifically to chemical processes that employ highly reactive OH hydroxyl radicals such as ozone (O3) or hydrogen peroxide (H2O2) combined with ultra violet (UV) energy, typically in an ‘in situ chemical oxidation’ process.

These reactive species can oxidize almost any compound present in water matrix. Oxidation fragments contaminants and converts them into small inorganic molecules. In advanced treatments, one or more primary oxidants, energy sources or catalysts like titanium dioxide can be applied in sequential precise, pre-programmed dosages and combinations to obtain maximum OH yields of hydroxyl radicals.

Generally speaking, AOP chemistry works in three phases:

• Phase 1: •OH formation
• Phase 2: Initial •OH breakdown of target molecules into fragments
• Phase 3: Subsequent •OH attacks for ultimate mineralization

The mechanism of •OH production is highly dependent on the AOP technique chosen, with ozonation hydrogen peroxide/UV, photocatalytic and other advanced oxidation using different models for •OH generation.

While there is little scientific consensus on how detailed mechanisms work in Phase 3, researchers have cast light on the processes of initial attacks in Phase 2. In essence, •OH is a radical species behaving as a highly reactive electrophile to produce Hydrogen Abstraction and Addition.

EnviroChemie AOP solutions

Advanced oxidation is particularly useful for scrubbing non-degradable toxins such as volatile organic compounds or aromatics from wastewater. They can also be used in tertiary treatment of previously filtered wastewater to reduce chemical contamination to the point where cleaned wastewater may be safely reintroduced into the environment.

EnviroChemie has modularized its AOP solutions for detoxification of water as Envochem® plant packages. These are available in three series:

• Envochem® AOP: treatment with hydrogen peroxide and UV radiation
• Envochem® AOP: treatment with hydrogen peroxide and iron2
• Envochem® AOP: treatment with ozone

Envochem® plants are widely used in pharmaceutical industries for chemico-physical water treatments.

These can include emulsion splitting of process water, detoxification of wastewater or removal of heavy metal residues.

Envochem plants incorporate a range of processes, separately or in combination. These can include precipitation, flocculation, sedimentation, activated charcoal adsorption and neutralization or oxidation using ozonation hydrogen peroxide/UV, photocatalytic and other advanced oxidation processes.

Resources

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