Removing Iron from Groundwater Using Oxidation Methods

How aeration, oxidation towers, catalytic media, and advanced oxidants eliminate iron problems at the source.

Iron is one of the most common groundwater contaminants worldwide. When present in its soluble form (ferrous iron, Fe²⁺), it may appear clear at the pump — but once exposed to oxygen, it rapidly converts to ferric iron (Fe³⁺) and forms rust-coloured sludge, staining, odours, biofilms, and blocked irrigation or filtration systems.

Oxidation is one of the most effective and environmentally friendly ways to remove iron from groundwater. This article explains how oxidation works, the most common oxidation technologies, and where each method is best applied.

Understanding Iron in Groundwater

Groundwater typically contains iron in one or more forms:

1. Ferrous Iron (Fe²⁺)

Dissolved, clear, and invisible. Requires oxidation to be removed.

2. Ferric Iron (Fe³⁺)

Oxidised, insoluble, forms orange/brown particles, sludge, or staining.

3. Iron Bacteria (IRB)

Microorganisms that feed on iron and produce gelatinous slime (“ferro”). Oxidation disrupts their structure.

4. Organic Iron

Complexes with humic acids; sticky, dark, difficult to remove without strong oxidants or specialty cleaners.

Oxidation methods target the conversion of Fe²⁺ → Fe³⁺ and the subsequent removal of the precipitated particles.

Why Oxidation Works

Oxidation increases the oxygen or electron-acceptor content in water, forcing dissolved iron to convert into solid particles. These particles can then be removed through filtration, sedimentation, or physical flushing.

General reaction:

Fe²⁺ + O₂ → Fe³⁺ → Fe(OH)₃ ↓ (rust/iron oxide)

Once oxidised, iron is no longer soluble and can be managed mechanically.

Common Oxidation Methods for Iron Removal

1. Aeration Towers (Air–Water Oxidation)

Aeration is one of the simplest and most cost-effective methods to oxidise iron.

How it works:

• Water is sprayed, cascaded, or trickled through a vertical aeration tower.

• Air is introduced naturally or via blowers.

• Oxygen reacts with dissolved iron, forming particles.

• A downstream sand, multimedia, or catalytic filter removes the precipitated iron.

Types of aeration systems:

• Spray aeration towers

• Cascade aerators (tray or stepped)

• Packed oxidation towers (contain media increasing contact time)

• Venturi aerators

• Air-stripping towers (dual-purpose for gases + iron)

Advantages:

✔ Chemical-free

✔ Low operating cost

✔ Ideal for moderate iron levels

Limitations:

• Less effective for high iron bacteria• May require large infrastructure footprint• Needs reliable downstream filtration

2. Catalytic Oxidation Media

Certain filtration media accelerate oxidation and capture iron simultaneously.

Common catalytic media include:

• Birm

• Filox / MangOx

• Greensand or Greensand Plus

• Manganese dioxide (MnO₂) coated media

How it works:

• Ferrous iron contacts the media surface.

• Catalytic sites convert Fe²⁺ to Fe³⁺ instantly.

• Particles are trapped until backwashing flushes them out.

Advantages:

✔ High efficiency

✔ Compact footprint

✔ Handles higher flow rates

Limitations:

• Requires specific pH ranges• Needs regular backwashing• Manganese removal may require stronger oxidants

3. Chemical Oxidation (Strong Oxidants)

For high levels of iron, iron bacteria, or organic contamination, stronger oxidants are used.

Common oxidants:

• Chlorine (sodium hypochlorite)

• Hydrogen peroxide

• Ozone

• Potassium permanganate

How it works:

These chemicals rapidly convert Fe²⁺ to Fe³⁺ and disinfect iron bacteria. The resulting particles are filtered or flushed away.

Best for:

✔ Iron bacteria

✔ High iron concentrations

✔ Mixed contaminants

Limitations:

• Requires dosing equipment

• Some oxidants (e.g., permanganate) stain if overdosed

• Higher operational complexity

4. Combined Oxidation & Filtration Systems

Modern systems often blend multiple approaches for improved efficiency:

• Aeration + catalytic filtration

• Ozone + sand filtration

• Peroxide injection + multimedia filters

• Air-injection valves + oxidising media tanks

These systems give excellent results for households, agriculture, commercial, and industrial water supplies.

Where BoreSaver Products Fit Into Oxidation-Based Iron Removal

Although oxidation removes iron from water, many groundwater bores become fouled with iron oxide, iron bacteria, and organic complexes deep inside the well itself. Oxidation alone cannot clean the bore structure — it only treats water at the surface.

To restore a fouled bore to full output:

BoreSaver chemical cleaners are used before or alongside oxidation-based water treatment systems.

BoreSaver Ultra C

A powerful, biodegradable treatment that dissolves:

• Iron oxide

• Iron bacteria slime

• Organic iron fouling

• Manganese deposits

This enables oxidation systems to work effectively by ensuring the bore itself is clean.

Aquatek + StainStopper Pulse

Prevents iron from oxidising inside irrigation systems by stabilising dissolved iron until it is safely dispersed.

GypKleen Soluble

For systems where oxidation reveals calcium sulfate (gypsum) rather than iron fouling — a separate issue requiring chemical dissolution.

When Oxidation Isn’t Enough

Oxidation treats water — not the bore.If the bore screen, gravel pack, or aquifer is blocked with ferro slime:

• Flow rates drop

• Pump strain increases

• Pressure reduces

• Staining worsens

In these cases, BoreSaver Ultra C combined with mechanical redevelopment (airlifting, surging, brushing) is the correct approach.

Final Thoughts

Oxidation is one of the most effective strategies for removing iron from groundwater. Whether using aeration towers, catalytic media, ozone, or chemical oxidants, the goal is always the same:

Convert dissolved iron into removable particles before it stains, clogs, or damages your system.

However, iron fouling inside the bore requires specialised cleaning solutions such as BoreSaver Ultra C to restore well performance.

A well-designed combination of bore rehabilitation, oxidation treatment, and ongoing maintenance provides the most reliable, long-term results.