What Is a Wet Scrubber System?

A wet scrubber is an air pollution control system that removes gases, odours, fumes and airborne particles from contaminated industrial air.

The system works by bringing the polluted air into direct contact with a scrubbing liquid. Depending on the contaminants present, the liquid may absorb, neutralise or capture pollutants before the treated air is released.

Wet scrubbers are commonly used to control ammonia, hydrogen sulphide, acidic gases, chemical fumes, dust and other industrial emissions.

Exeon’s scrubX™ is a compact, containerised wet scrubber designed for industrial odour control and air emission treatment. Its packaged construction allows the system to be installed quickly while reducing the amount of on-site assembly required. Read more about what a wet scrubber system is.

How Does the scrubX Wet Scrubber Work?

Contaminated air enters the bottom of the scrubX™ system and travels upwards through a packed treatment tower.

At the same time, a specially formulated scrubbing liquid flows downwards across the packing media. The media creates a large contact area between the polluted air and the liquid, allowing gases, odours and other contaminants to be absorbed or neutralised.

The treated air then passes through a mist eliminator, which captures remaining liquid droplets before the air is discharged.

The scrubbing solution is recirculated through the system and monitored using automated controls. Chemical dosing can then be adjusted to maintain the correct treatment conditions and consistent pollutant removal. Learn more about how a wet scrubber works.

What Pollutants Can a Wet Scrubber Remove?

Wet scrubbers can remove a wide range of gaseous, odorous and particulate pollutants from industrial air streams.

Common contaminants include ammonia, hydrogen sulphide, sulphur dioxide, hydrogen chloride, acidic gases, chemical fumes and certain volatile organic compounds. Wet scrubbers can also capture dust, fine particles, odorous compounds and some industrial contaminants.

The pollutants that can be treated will depend on their chemical properties, concentration and ability to react with or dissolve in the selected scrubbing solution.

Before specifying a system, the air stream should be assessed to identify the contaminants present and determine the appropriate scrubber design, chemical treatment and required removal efficiency. Learn more about the pollutants that a wet scrubber can remove.

Which Industries Use Wet Scrubber Systems?

Wet scrubber systems are used across industries where harmful gases, unpleasant odours, corrosive fumes or airborne particles must be controlled.

Common applications include wastewater treatment, sewage works, waste processing, recycling facilities, composting operations and anaerobic digestion plants.

Wet scrubbers are also used within food production, abattoirs, chemical manufacturing, pharmaceutical production, metal processing, foundries and energy facilities.

Each industry produces a different mixture of emissions, so the system must be designed around the specific process and contaminants involved.

Exeon’s scrubX™ systems are available in several airflow capacities and can be configured around the operating requirements, available space and environmental obligations of each site. Discover the industries who use wet scrubber systems.

How Is the Correct Scrubbing Chemical Selected?

The scrubbing chemical is selected according to the pollutants that need to be removed from the contaminated air.

Acidic gases may require an alkaline scrubbing solution, while alkaline contaminants such as ammonia may need an acidic solution. Oxidising chemicals can also be used where pollutants such as hydrogen sulphide need to be converted into less harmful compounds.

The correct chemical concentration, pH level and dosing rate are essential for effective treatment.

Airflow, contaminant concentration, temperature and moisture levels must also be considered when selecting the solution.

Exeon assesses the expected emissions and process conditions before recommending the appropriate chemical treatment and automated dosing arrangement for the scrubX™ system. Read more about selecting the correct scrubbing chemical.

How Is a Wet Scrubber System Sized?

A wet scrubber is sized according to the volume of contaminated air, the pollutants present and the required removal efficiency.

Important considerations include airflow rate, contaminant concentration, temperature, moisture content and the amount of contact needed between the polluted air and the scrubbing liquid.

The ductwork, fan capacity and pressure resistance across the system must also be considered to ensure the required airflow can be maintained.

The scrubX™ range includes models capable of treating different air volumes, with multiple units available for larger applications.

Systems can also be installed in parallel or stacked where plant space is limited, allowing the treatment capacity to be adapted to the site. Discover exactly how a wet scrubber system is sized.

What Removal Efficiency Can a Wet Scrubber Achieve?

The removal efficiency of a wet scrubber depends on the pollutant, system design, chemical treatment and operating conditions.

Exeon’s scrubX™ range is designed to provide a minimum removal efficiency of approximately 96% based on expected site inputs. Efficiencies of 99% or higher may be possible where the system is correctly designed and operated for the target contaminant.

Performance can be influenced by airflow, chemical concentration, liquid distribution, contact time and the condition of the packing media.

Accurate information about the incoming air stream is therefore important when establishing the required system specification.

Monitoring should also be used to confirm that the expected treatment performance is being maintained. Find out more about the removal efficiency of a wet scrubber.

What Maintenance Does a Wet Scrubber Require?

Wet scrubbers require regular inspection and servicing to maintain effective and reliable emission control.

Routine maintenance may include checking spray nozzles, pumps, fans, dosing equipment, liquid levels, pH sensors and control systems. The packing media and mist eliminator should also be inspected for blockages, scale or accumulated deposits.

The scrubbing liquid may need to be replaced or treated depending on the pollutants captured and the operating conditions.

Pipework, chemical storage areas and access seals should also be checked for leaks or deterioration.

A planned maintenance schedule helps prevent reduced airflow, inefficient chemical use and unexpected loss of treatment performance while supporting the long-term reliability of the system. Understand the maintenance needed for a wet scrubber system.

What Happens to the Used Scrubbing Liquid?

As the scrubbing liquid circulates through the system, it collects or reacts with pollutants removed from the contaminated air.

Over time, the liquid may contain dissolved salts, suspended particles, reaction products or other contaminants. A proportion of the solution may therefore need to be removed through a controlled process known as blowdown.

The used liquid must then be handled, treated or disposed of according to its chemical composition and the relevant environmental requirements.

Fresh water and treatment chemicals can be added to maintain the correct operating conditions within the scrubber.

The required wastewater management process should be considered during system design so that liquid handling remains safe, practical and compliant. Learn more about what happens to the used scrubbing liquid.

Can scrubX Be Combined with Other Air Treatment Systems?

The scrubX™ wet scrubber can operate independently or form part of a multi-stage air emission control system.

An activated carbon filter may be installed after the scrubber to provide a final polishing stage and remove residual odours or contaminants. Pre-filtration may also be used where the incoming air contains high levels of dust or particulate matter.

In some applications, different scrubber stages may be required to treat several pollutants with different chemical properties.

Combining technologies can improve overall treatment performance where emissions are complex, variable or subject to demanding discharge limits.

The most suitable arrangement should be determined through air testing, process assessment and consideration of the required removal efficiency and operating costs. Discover more about the air treatments that wet scrubbers can be used with.