Removing Arsenic from Water with Bayoxide® E33 Filtration Systems

Arsenic contamination is a serious concern for some private water supplies, particularly boreholes and wells where naturally occurring arsenic can dissolve into groundwater.

Unlike iron or manganese, arsenic generally does not cause noticeable staining, taste or odour problems. A water supply can appear perfectly clear while containing arsenic above the permitted drinking water limit.

Fortunately, specialist treatment media such as Bayoxide® E33 can be highly effective at reducing arsenic concentrations when the system is correctly designed for the water conditions.

In this guide, we explain how Bayoxide E33 works, the importance of arsenic speciation, and the factors that influence treatment performance.

What Is the UK Drinking Water Limit for Arsenic?

The UK drinking water standard for arsenic is:

10 µg/L (micrograms per litre), equivalent to 0.010 mg/L.

This applies to drinking water supplied through the public mains and to private supplies.

Long-term exposure to elevated levels of inorganic arsenic in drinking water has been associated with serious health effects, including an increased risk of certain cancers.

If testing identifies arsenic above the drinking water standard, the supply should not be relied upon for drinking or food preparation until appropriate advice has been obtained and treatment effectiveness has been verified.

For private water supplies, the local authority's environmental health team can provide advice on testing and the applicable requirements.

What Is Bayoxide® E33?

Bayoxide E33 is a specialist granular iron oxide hydroxide adsorbent manufactured by LANXESS.

It has been developed specifically for removing arsenic and certain other dissolved contaminants from water.

Unlike a conventional sediment filter, which physically traps suspended particles, Bayoxide works through adsorption.

As water passes through the media bed, dissolved arsenic binds to the surface of the iron oxide hydroxide particles.

Its large surface area provides numerous adsorption sites, allowing the media to retain arsenic as the water passes through.

Bayoxide E33 is commonly installed in a pressure vessel containing a supporting gravel bed, with a suitable control valve to manage water flow and periodic backwashing.

Understanding Arsenic: As(III) vs As(V)

One of the most important considerations when selecting an arsenic removal system is the chemical form of arsenic present in the water.

In groundwater, inorganic arsenic commonly occurs in two forms:

Arsenic form	Description
Arsenite – As(III)	Often associated with low-oxygen groundwater conditions
Arsenate – As(V)	More common in oxidising water conditions

Can Bayoxide E33 Remove Both Forms?

Yes. LANXESS confirms that Bayoxide E33 can adsorb both As(III) and As(V).

However, arsenate As(V) is generally more readily removed, and converting As(III) to As(V) before treatment can significantly improve adsorption efficiency and potentially extend the useful life of the media.

Where a water supply contains a substantial proportion of As(III), an oxidation stage may therefore be recommended before the Bayoxide vessel.

The need for oxidation depends on the source water chemistry and the proposed treatment design.

Importantly, Bayoxide E33 should not be relied upon as the oxidation stage itself.

What Affects Bayoxide E33 Performance?

Although Bayoxide E33 has a high arsenic adsorption capacity, its performance depends on several factors.

1. Water pH

pH can have a considerable influence on arsenic adsorption.

The manufacturer specifies a broad operating pH range of approximately 5.5–8.5.

However, this does not mean that identical arsenic removal performance will be achieved throughout that range.

Water with a higher pH may have reduced adsorption efficiency, depending on the arsenic species and other dissolved constituents.

For this reason, the incoming pH should always be considered when evaluating an arsenic removal system.

2. Phosphate and Silica

Phosphate and dissolved silica can compete with arsenic for adsorption sites on the media.

High concentrations can reduce the available capacity for arsenic and shorten the operating life of the filter.

These parameters are particularly important when estimating media consumption and replacement intervals.

3. Iron, Manganese and Suspended Solids

Where the water contains iron, manganese or significant turbidity, additional treatment may be necessary.

Oxidised iron and other suspended particles can accumulate within the Bayoxide bed, increasing pressure loss and potentially interfering with effective treatment.

Removing these contaminants before the arsenic adsorption stage may help maintain more consistent performance.

4. Arsenic Concentration

The higher the arsenic concentration entering the filter, the more rapidly the media's available adsorption capacity will be consumed.

A system treating water containing 20 µg/L arsenic will not necessarily have the same operating life as one treating water containing 100 µg/L.

Media capacity must therefore be considered in relation to the actual untreated water analysis.

5. Water Flow Rate and Contact Time

Arsenic adsorption requires sufficient contact time between the water and the media.

If water passes through the vessel too quickly, the available adsorption capacity may not be used effectively.

The required contact time depends on the water chemistry, treatment target and system configuration.

A high flow rating alone does not guarantee effective arsenic removal. The quantity of media and the available contact time must also be suitable.

How Does a Bayoxide Arsenic Removal System Work?

A typical Bayoxide treatment system consists of:

Pre-treatment, where required: To remove iron, sediment or other contaminants and provide suitable oxidation conditions.
Bayoxide pressure vessel: Contains the adsorption media that removes dissolved arsenic.
Control valve: Manages service flow and any programmed backwashing.
Sampling points: Allow arsenic concentrations to be checked before and after treatment.

GAPS Water Treatment supplies Bayoxide systems incorporating Clack and Autotrol control valves in a selection of vessel sizes.

These systems can be used as part of a properly designed treatment arrangement for private water supplies and commercial applications.

View our Bayoxide Arsenic Reduction Systems

Why Use Two Bayoxide Vessels in Series?

For some applications, particularly where arsenic concentrations are elevated or a higher level of treatment assurance is required, a two-vessel lead-lag arrangement may be appropriate.

In this configuration:

The first vessel (lead) removes most of the arsenic.
The second vessel (lag) provides an additional adsorption stage.
A sampling point between the vessels allows the performance of the first vessel to be monitored.
The final outlet is also tested to verify the quality of the treated water.

As the first vessel approaches exhaustion, arsenic may begin appearing at the intermediate sampling point.

This provides an opportunity to replace the exhausted media before arsenic reaches the final outlet, provided the lag vessel still has sufficient capacity.

Once the lead vessel has been serviced, the vessels may be rotated as part of a planned maintenance programme.

This arrangement can provide additional protection against breakthrough, although regular monitoring remains essential.

Does Bayoxide E33 Need Regenerating?

No. Unlike water softener resin, Bayoxide E33 is not normally regenerated with salt or other chemicals.

The media progressively becomes exhausted as its adsorption sites are occupied.

Once its available capacity has been used, the exhausted media must be replaced.

A control valve may perform periodic backwashing to remove accumulated particles and redistribute the bed, but this does not restore the arsenic adsorption capacity.

Spent media must be assessed and disposed of in accordance with the applicable waste requirements.

How Do You Know When Bayoxide Needs Replacing?

Arsenic cannot be detected by the appearance, taste or smell of the treated water.

As the media approaches exhaustion, arsenic may begin to pass through the filter. This is known as breakthrough.

The only reliable way to establish whether the system is continuing to achieve the required arsenic reduction is through appropriate water testing.

A monitoring programme should include:

Testing untreated water to establish the incoming arsenic concentration.
Testing the treated water after installation and commissioning.
Periodic testing to identify changes in performance.
Intermediate sampling where lead-lag vessels are installed.
Media replacement before the treated water exceeds the required limit.

The testing frequency should reflect the risks associated with the supply, arsenic concentration, expected media life and treatment configuration.

There is no universal replacement interval suitable for every installation.

What Information Is Needed to Size an Arsenic Removal System?

For accurate equipment selection, we recommend a comprehensive water analysis.

Ideally, this should include:

Total arsenic concentration.
Arsenic speciation (As(III) and As(V)), where available.
pH.
Iron and manganese.
Phosphate.
Silica.
Turbidity.
Other relevant dissolved minerals and contaminants.

The system must also be sized for the required flow rate and daily water consumption.

If the supply contains other contaminants, additional treatment stages may be necessary.

Frequently Asked Questions

Can Bayoxide E33 reduce arsenic below 10 µg/L?

Yes. Bayoxide E33 has demonstrated the ability to reduce arsenic concentrations below the UK drinking water standard under suitable operating conditions.

However, the result depends on water chemistry, correct system design, contact time and media condition.

Treatment performance must be verified through testing.

Does Bayoxide remove arsenic As(III)?

Yes. Bayoxide E33 can adsorb As(III), but pre-oxidation to As(V) can improve treatment efficiency and media capacity.

Does a UV system remove arsenic?

No. Ultraviolet treatment is used for microbiological disinfection and does not remove dissolved arsenic.

Will a conventional sediment or carbon cartridge remove arsenic?

Standard sediment cartridges and conventional activated carbon filters should not be relied upon for dissolved arsenic removal.

Specialist adsorption media or other appropriately designed treatment technologies are required.

Can reverse osmosis remove arsenic?

Yes. Reverse osmosis can be effective, particularly for As(V). Performance for As(III) can be lower, so oxidation or other pretreatment may be required.

Reverse osmosis is often considered where only a dedicated drinking water supply requires treatment.

Is Bayoxide suitable for private borehole water?

Yes. Bayoxide E33 is used for treating groundwater containing arsenic.

However, the water chemistry must be assessed before selecting the equipment, and the treated water must be monitored to verify performance.

Bayoxide E33 Arsenic Reduction Systems from GAPS Water Treatment

At GAPS Water Treatment, we supply genuine Bayoxide E33 media and a selection of arsenic reduction systems incorporating Clack and Autotrol control valves.

Our range includes systems for domestic, commercial and industrial applications.

Browse Bayoxide Arsenic Reduction Systems

Buy Bayoxide E33 Filtration Media

If you require an arsenic reduction system, please email your water analysis and details of your required flow rate and daily consumption to sales@gapswater.co.uk.

We can help you assess suitable equipment and provide a quotation.

GAPS Water Treatment is a supply-only business. Equipment suitability and treatment performance must be confirmed through appropriate water analysis, installation and commissioning.

Removing Arsenic from Water with Bayoxide® E 33 Filtration Systems