Advanced oxidative processes, reverse osmosis, ion exchange method

1. Advanced Oxidation Processes ,
Reverse Osmosis, Ion Exchange
Method
Santhiya C
22ENVA16
ENVIRONMENTAL ENGINEERING

2. INTRODUCTION
• Tertiary Treatment is the extra treatment after biological secondary processes to further stabilize oxygen-
demanding substances in the wastewater, to remove nitrogen and phosphorus or to eliminate
microorganisms and pathogens
• Tertiary treatment adds a third, more advanced and rigorous level of treatment. Primary and secondary
treatment typically get wastewater only clean enough to discharge safely into the environment. Tertiary
treatment, on the other hand, can achieve levels of water purification that make the water safe for reuse
in water-intensive processes or even as drinking water.
• Various tertiary methods include Advanced oxidation processes, Reverse osmosis, Ion exchange method,
etc.

3. ADVANCED OXIDATION PROCESSES (AOPs)
• Advanced Oxidation Processes (AOPs) are a group of chemical treatment techniques used for wastewater
treatment. They involve the generation of highly reactive oxygen species like hydroxyl radicals to degrade
organic and inorganic pollutants in water.
• Examples of AOPs include ozonation, photocatalysis, and Fenton's reagent.
• Challenges of Conventional Treatment: Conventional wastewater treatment processes like biological
treatment and physical-chemical methods may struggle to effectively remove persistent contaminants due to
their chemical stability and resistance to microbial degradation.
• Role of AOPs: Advanced Oxidation Processes (AOPs) are designed to tackle persistent contaminants by
generating highly reactive species like hydroxyl radicals. These radicals can break down the chemical
bonds of pollutants that are resistant to traditional treatment methods

4. OZONATION
• Ozonation is an Advanced Oxidation Process (AOP) used for wastewater treatment. It involves the
application of ozone (O3), a powerful oxidizing agent, to degrade organic and inorganic contaminants in
water.
• Ozone Generation: Ozone is produced by passing dry air or oxygen through an electrical discharge,
generating ozone molecules. These ozone molecules are then injected into the wastewater to initiate the
treatment process.
• Mechanism of Action: Ozonation works through the reaction of ozone molecules with pollutants. Ozone
is highly reactive and can break down the double bonds present in organic compounds. It can also react
with inorganic substances through processes like oxidation and hydrolysis.

5. OZONATION
• Organic Pollutant Degradation: Ozone attacks the chemical structure of organic pollutants, leading to
the cleavage of bonds and the formation of smaller fragments. This fragmentation makes complex
organic compounds easier to biodegrade or remove through subsequent treatment steps.
• Inorganic Pollutant Transformation: Ozonation can lead to the transformation of inorganic pollutants.
For example, ozone can oxidize iron and manganese into solid particles that can be filtered out. It can
also convert some inorganic contaminants into less harmful forms.

6. OZONATION
Advantages of Ozonation:
• Effective for a wide range of pollutants, including organic compounds, pathogens, and odor-causing
substances.
• Produces no harmful by-products, as ozone decomposes into oxygen.
• Does not leave chemical residues in the treated water.
• Can improve water color and remove taste and odor issues.
Challenges and Considerations:
• Energy-intensive process due to ozone generation requirements.
• Proper mixing and contact time are essential for efficient pollutant removal.
• Management of generated ozone gas to ensure worker safety and prevent atmospheric pollution.
• Selection of appropriate operating conditions based on the specific contaminants present.

7. PHOTOCATALYSIS
• Photocatalysis is an Advanced Oxidation Process (AOP) that utilizes light-activated catalysts to degrade
pollutants in wastewater. It involves the use of photocatalysts to initiate oxidation reactions under
illumination.
• Photocatalyst Types: Common photocatalysts include titanium dioxide (TiO2), zinc oxide (ZnO), and
various semiconducting materials. These materials absorb light energy, creating electron-hole pairs that
participate in redox reactions with pollutants.
• Mechanism of Photocatalytic Reaction: When a photocatalyst absorbs photons from light, it generates
electron-hole pairs. Electrons in the conduction band and holes in the valence band are involved in
oxidation and reduction reactions with pollutants, respectively

8. PHOTOCATALYSIS
• Degradation of Organic Pollutants: During photocatalysis, the generated electron-hole pairs react with
organic pollutants adsorbed on the catalyst's surface. This leads to the formation of highly reactive
radicals, such as hydroxyl radicals, that attack and degrade the pollutants.
• Environmental Benefits:
 Efficient removal of a wide range of organic pollutants, including dyes, pesticides, and
pharmaceuticals.
 Reduction in pollutant toxicity and environmental impact.
 Potential for the removal of pathogenic microorganisms.

9. FENTON’S REAGENT
• Fenton's Reagent is a chemical treatment method used in wastewater treatment to degrade organic and
inorganic pollutants. It involves the reaction between hydrogen peroxide (H2O2) and a ferrous iron
catalyst (Fe2+).
• Fenton's Reaction Mechanism: In the Fenton's reaction, H2O2 reacts with Fe2+ ions to form hydroxyl
radicals (OH•) and ferric ions (Fe3+). The hydroxyl radicals are highly reactive and play a key role in
pollutant degradation.

10. FENTON’S REAGENT
• Organic Pollutant Degradation: During Fenton's reaction, hydroxyl radicals attack the organic
pollutants present in wastewater. This leads to the cleavage of carbon-carbon and carbon-hydrogen
bonds, resulting in the decomposition of complex organic compounds.
• Effect on Inorganic Pollutants: Fenton's Reagent can also transform some inorganic pollutants. For
example, it can oxidize metals like arsenic and chromium, converting them into less soluble and less
toxic forms that are easier to remove from water.

11. FENTON’S REAGENT
Advantages of Fenton's Reagent:
• Effective for a wide range of organic pollutants, including those that are recalcitrant to other treatment
methods.
• No need for additional chemicals, as Fe2+ and H2O2 are readily available.
• Hydroxyl radicals are short-lived and do not leave harmful residues in treated water.
Limitations and Considerations:
• Optimal pH and Fe2+ concentration are critical for efficient hydroxyl radical generation.
• Excessive Fe2+ concentrations can result in sludge formation and increased treatment costs.
• Iron-based residuals might need to be managed in the treatment process.

12. REVERSE OSMOSIS
• Reverse osmosis is a filtration process used in tertiary wastewater treatment.This method is effective for
producing high-quality water suitable for various non-potable uses, such as irrigation or industrial
processes.
• The principle of reverse osmosis involves using pressure to push water through a semipermeable
membrane, which allows water molecules to pass through while blocking larger contaminants and
impurities. This results in the separation of clean water from the concentrated solution, effectively
purifying the water.

13. The reverse osmosis process in tertiary wastewater treatment involves several key steps:
• Remove larger
particles, debris and
suspended particles
Pre-treatment
• Pump pressurizes
pre-treated
wastewater.
Pressurization
• Pressurized
wastewater enters
semipermeable
membrane.
Membrane
separation
• Two streams
generated - purified
permeate and
concentrated reject.
Permeate and
concentrate • Additional
treatment for
purified water (UV
disinfection, carbon
filtration).
Post-treatment
• Proper
management of
concentrate stream
Disposal of
concentrate
REVERSE OSMOSIS

14. REVERSE OSMOSIS
• Benefits of RO:
 Effective Contaminant Removal: Reverse osmosis efficiently removes contaminants, including
dissolved solids, salts, organic compounds, bacteria, viruses, and other impurities, producing high-
quality treated water.
 Reuse: The process creates reusable water for activities like farming and industry.
 Desalination: Reverse osmosis is a critical technology for desalinating seawater or brackish water
 Reduced Environmental Impact: The process minimizes the discharge of pollutants into natural
water bodies, thus contributing to environmental protection and the health of ecosystems.
• Disadvantages of RO:
 Energy Demand: It needs a lot of energy, increasing costs and environmental impact.
 Membrane Fouling: The membrane can get clogged, leading to reduced efficiency and frequent
cleaning.
 High Pressure: Operating at high pressure can damage equipment and requires strong infrastructure.
 Disposal Challenge: The concentrate produced has concentrated pollutants, needing proper disposal

15. ION EXCHANGE METHOD
• The ion exchange method is a common technique used in wastewater treatment to remove ions and
impurities from water.
• This process is often used to remove heavy metals, radioactive substances, and other pollutants from
wastewater before it's discharged or reused.
• The principle behind the ion exchange method in wastewater treatment is based on the concept of
selective adsorption and exchange of ions between a solid medium (ion exchange resin) and a liquid
medium (wastewater). The resin captures undesired ions and releases less harmful ones, effectively
purifying the water.

16. ION EXCHANGE METHOD
The ion exchange process in wastewater treatment includes various steps:
•Select resin with
functional groups
for specific ions.
Preparation of Ion
Exchange Resin
•Wastewater
passes through
a resin-
containing
column
Contact with
Wastewater •Undesirable ions
attach to resin's
functional groups.
Ion
Exchange
•Resin becomes
saturated with captured
ions, treatment
efficiency decreases.
Saturation:
•Pass
regenerating
solution through
resin bed.
Regeneration
•Captured
contaminants form
regeneration waste,
requiring proper
disposal.
Waste
Disposal
•Rinse resin, let it
equilibrate with
desired ions
before reuse
Rinse and
Equilibration

17. ION EXCHANGE METHOD
• ADVANTAGES:
 Ion exchange is highly effective at removing specific ions and contaminants such as heavy metals,
radioactive elements, and dissolved salts.
 Ion exchange often requires fewer chemicals to achieve the same level of purification.
 Unlike some treatment methods, ion exchange generates minimal sludge, which reduces the amount of
waste that needs to be managed and disposed of.
 The method allows for the selective removal of targeted pollutants. Different types of ion exchange
resins can be used to target specific ions, enablingtreatment based on the composition of the
wastewater.
• DISADVANTAGES:
 Waste Generation from the process requires proper disposal
 Ion exchange resin degrade due to exposure to chemicals or extreme pH conditions reducing the
efficiency and lifespan of the resin, necessitating more frequent replacement.
 Require regular monitoring and maintenance to ensure proper operation
 The initial investment and operational costs are incurred for regeneration, resin replacement,and
system maintenance
 They still require physical space for resin beds, regeneration equipment, and associated infrastructure.
 Regeneration processes may require energy-intensive steps, in cases where heat or pressure is needed
to facilitate ion exchange.

18. THANK YOU