Exhaust air treatment is an essential part of many industrial processes. During the use and processing of chemical substances, contaminated exhaust gases are often generated – containing pollutants such as amines, ammonia, chlorine, ozone or organic compounds. These substances can endanger human health, attack materials and have a lasting impact on the environment and climate.
Effective exhaust air purification is therefore crucial – protecting people and the environment while ensuring operational safety and process reliability.
HLU provides customized exhaust air treatment systems designed to meet the specific requirements of each application. Whether packed bed scrubbers, crossflow scrubbers, absorption or adsorption systems, our solutions are precisely matched to the process medium, air volume and industry-specific demands. They reliably remove, neutralize or recover pollutants, ensuring efficient, safe and long-lasting operation.
Exhaust Air Treatment Tailored to Your Process
Efficient aerosol abatement
clean air through advanced technology
In many industrial processes, extremely fine aerosols are generated that conventional filtration systems cannot reliably remove. These aerosols not only impair air quality but also cause health risks and cause deposits in downstream equipment. Our high-efficiency aerosol separators ensure safe and reliable removal.
How does it work?
Our aerosol separators use a combination of specially designed wire mesh structures and optimized scrubbing processes to remove aerosols from the air stream. The wire mesh provides high separation efficiency even for the smallest liquid droplets, ensuring that the air is effectively cleaned. In addition, scrubbing liquids or coalescence mechanisms can be used to further enhance efficiency.
Your benefits at a glance:
- High-efficiency separation - reliable even for the finest aerosols
- Innovative wire mesh technology - optimal droplet separation
- Flexible application - adaptable to various process requirements
- Minimization of deposits - protects downstream equipment
- Cost-effective operation - low maintenance and long service life
- Compliance with regulatory requirements - supports emission reduction
Efficient removal of amines
with HLU exhaust air scrubbers
Amine-rich exhaust gases require advanced pollution control due to their strong odors and severe environmental and health hazards. Our packed-bed columns and cross-flow scrubbers efficiently remove amines via selective absorption and chemical binding.
How does it work?
1.) Absorption
The amine-containing exhaust air is passed through a packed-bed column or a cross-flow scrubber. Here, the amines are absorbed into water, supported by the addition of sulfuric acid. The amines are thereby converted into water-soluble amine sulfates.
2.) Optimal process control through pH control
Precise pH control ensures that amine removal is efficient and stable. Our systems are designed to maintain consistently high absorption performance even under strongly fluctuating gas concentrations.
3.) Safe handling of the scrubbing medium
The amine-rich scrubbing solution is further treated or disposed of in accordance with legal regulations.
Your benefits at a glance:
- Effective removal of amines from exhaust air
- High operational reliability through precise pH control
- Flexibility under fluctuating air concentrations
- Durable, low-maintenance technology for reliable operation
Efficient ammonia removal
with HLU exhaust air scrubbers
Driven by environmental pollution, regulatory requirements for ammonia emissions are becoming increasingly stringent for companies. Our packed-bed columns and cross-flow scrubbers ensure reliable removal of ammonia from exhaust air streams - economical, sustainable, and safe!
How does it work?
Ammonia is absorbed in water and then reacts with sulfuric acid to form valuable ammonium sulfate. The product is obtained as a 40 % solution containing 8 % ammonium nitrogen - ideal for use as a fertilizer in agriculture. This allows you to turn emissions into a valuable resource!
Your benefits at a glance
- Effective ammonia removal - meets strict environmental regulations
- Sustainable utilization - ammonium sulfate as a marketable by-product
- Optimized process control - low chemical consumption, maximum efficiency
- Customized solutions - perfectly tailored to your requirements
Safe chlorine removal
reliable exhaust air treatment for your processes
Elemental chlorine (Cl2) is a highly reactive and toxic gas that is not only detrimental to human health but also highly corrosive to equipment. Our packed-bed columns and cross-flow scrubbers provide reliable Cl2 removal to effectively protect people, the environment, and plant systems - safe, efficient, and individually adaptable.
How does it work?
The contaminated exhaust gas is passed through a packed-bed column or a cross-flow scrubber, where caustic soda (sodium hydroxide solution) is added to the scrubbing liquid. Chlorine is chemically converted into hypochlorite and chloride. To remove the hypochlorite, sodium bisulfite solution or hydrogen peroxide is additionally added to the scrubbing liquid. These reagents ensure complete reduction of the chlorine, so that no hazardous residues remain in the wastewater stream.
- Bromine (Br2) can be removed in the same way as chlorine.
Your benefits at a glance
- Effective chlorine removal - safe elimination of a toxic and highly reactive pollutant
- Chlorine destruction - chemical reduction for Cl2-free wastewater
- Flexible application - individually adaptable to various process requirements
- Optimized use of chemicals - cost-effective operation with high efficiency
- Reliable compliance with environmental regulations - minimizes Cl2 emissions
Effective removal of chromic acid mist
reliable protection for people and the environment
Chromic acid mists generated during electroplating processes or chemical treatments endanger human health and the environment. Our chromic acid mist eliminators ensure reliable removal and prevent hazardous chromium(VI) aerosols from entering the atmosphere.
How does it work?
The contaminated exhaust air stream is passed through a specially designed scrubbing column, where the chromic acid droplets are effectively captured. A key component of our technology is the use of specialized wire mesh structures, which enable highly efficient mechanical droplet separation. With their large surface area, these structures ensure that even the finest chromic acid mists are safely removed.
Your benefits at a glance
- High-efficiency separation - reliable removal of chromium(VI) aerosols and mists
- Innovative wire mesh technology - maximum separation performance even for the finest droplets
- Adaptable systems - flexible adjustment to different process conditions
- Durable, low-maintenance technology - robust design for continuous operation
- Compliance with regulatory limits - ensures adherence to strict environmental requirements
Effective removal of organic compounds
sustainable gas treatment with water
Volatile organic compounds (VOCs) present critical risk to both environmental stability and human health. While thermal processes such as regenerative thermal oxidization are often associated with high investment costs and significant CO2 emissions, our scrubbing process offers an economical and eco-friendly alternative for water-soluble organic substances.
How does it work?
Water serves as the scrubbing medium in a specially designed packed-bed column to treat the contaminated exhaust gas. Using a counter-current principle, the organic compounds are efficiently dissolved in the washing liquid and thus removed from the exhaust air. The resulting contaminated wastewater typically needs to be further treated in a biological wastewater treatment plant to break down the dissolved organic substances.
Your benefits at a glance
- Effective removal - reliable elimination of water-soluble organic compounds
- Eco-friendly process - no aggressive chemicals
- Flexible system design - adaptable to different concentrations and flow rates
- Cost-effective operation - low maintenance requirements and resource-efficient water use
- Safe operation - ATEX design available if required, electrically conductive materials, explosion-pressure-resistant construction
- Integrated solution - requires biological wastewater treatment for safe further processing
- Compliance with legal emission standards - reliable reduction of organic pollutants
Efficient gas treatment with activated carbon adsorbers
reliable removal of organic pollutants
Volatile organic compounds (VOCs) present critical risk to both environmental stability and human health. Our activated carbon adsorbers provide an efficient, economical, and proven solution for cleaning contaminated exhaust gas streams - ideal for a wide range of industrial applications.
How does it work?
The contaminated exhaust gas stream is passed through a bed of activated carbon, which effectively binds pollutants through adsorption. This method is particularly suitable for low pollutant concentrations and exhaust gas streams where wet scrubbing or thermal processes are uneconomical or not technically feasible. The spent activated carbon can be regenerated or safely disposed of, depending on the application.
Your benefits at a glance
- High removal efficiency - reliable for VOCs and solvent vapors
- Cost-effective alternative - significantly lower investment costs than thermal processes
- Flexible system design - modular and adaptable to different flow rates and pollutant concentrations
- Easy handling - low maintenance requirements, simple activated carbon management
- Sustainable solution - activated carbon regeneration for resource conservation
Efficient ozone destruction
safe conversion into non-toxic oxygen with activated carbon
Ozone (O3) is generated in various technical processes, particularly in UV disinfection systems as well as plasma and ozone generators. Since ozone is a strong oxidizing agent, it must be safely removed in many applications before being released into the environment. Our specially developed activated carbon enables rapid and reliable decomposition of ozone into non-toxic oxygen (O2) - without any chemical additives or by-products.
How does it work?
The ozone-laden exhaust gas stream is passed through a bed of highly reactive activated carbon. The activated carbon catalyzes the decomposition of ozone by converting the unstable O3 molecule into harmless molecular oxygen (O2). The process is purely catalytic, without additional chemicals or waste.
Your benefits at a glance
- Effective ozone destruction - rapid and complete conversion into oxygen
- Eco-friendly process - no harmful by-products or waste
- No energy requirement - purely catalytic reaction, no external energy input needed
- Durable and low-maintenance - activated carbon with long service life
- Flexible system design - ideal for a wide range of applications, from laboratory air to industrial processes
- Easy integration - easily retrofittable into existing exhaust air systems
Efficient removal of phosphorus pentoxide and phosphoric acid aerosols
with high-performance filter candles
P4O10 typically generates during high-temperature processes where phosphorus compounds oxidize. In humid exhaust gases, P4O10 reacts to form phosphoric acid aerosols. These finely dispersed droplets are highly corrosive, posing a significant risk to both the environment and downstream plant equipment.
Our specially designed separators equipped with filter candles offer a highly efficient solution for removing these aerosols from the gas stream - compact, reliable, and low-maintenance.
How does it work?
The aerosol-laden gas stream is routed through a vessel containing filter candles made of glass or synthetic fibers. Physical filtration occurs via a combination of mechanical interception, inertial impaction, and diffusion. This process reliably retains the aerosols on the filter surface, allowing them to be continuously drained.
Your benefits at a glance:
- Reliable separation of ultra-fine aerosols with collection efficiencies up to 99.99 %
- Corrosion-resistant construction ideally suited for highly aggressive media
- Compact footprint perfect for retrofitting or integrating into existing systems
- Low maintenance costs thanks to long-lasting filter candles and easy handling
- High operational reliability even under fluctuating process conditions
Efficient mercury removal
safe gas treatment with impregnated activated carbon
The environmental and health hazards associated with mercury are substantial, even in very small quantities. Our specially impregnated activated carbon enables efficient and reliable removal of both metallic and ionic mercury from industrial exhaust gas streams - a proven solution for a wide range of applications, from waste incineration to metal processing.
How does it work?
The contaminated exhaust gas stream is passed through a bed of specially impregnated activated carbon, which binds mercury through chemical reactions and adsorption. This technology ensures high removal efficiency even at low mercury concentrations and prevents re-emission into the environment. The spent activated carbon can then be safely disposed of or recycled.
Your benefits at a glance
- Highly efficient mercury removal - reliable elimination of metallic and ionic mercury
- Safe and stable binding - no re-emission of mercury
- Flexible system design - adaptable to various industrial processes
- Low operating costs - an economical alternative to complex wet scrubbers
- No water consumption - no wastewater treatment required
- Easy handling - simple replacement and safe disposal of activated carbon
Reliable acid gas abatement
clean air with our gas scrubber
Acidic exhaust gases laden with HCl, HF, HNO3, SO2, or acetic acid have a significant environmental impact and require reliable treatment. Our highly efficient packed-bed columns and cross-flowscrubbers remove acidic pollutants from exhaust air streams, ensuring a sustainable reduction of harmful emissions – economically, safely, and effectively.
How does it work?
The acidic components are dissolved in the scrubber through absorption in water with subsequent neutralization with caustic soda. The resulting salts vary in environmental compatibility, depending directly on the composition of the pollutants. For problematic wastewater, such as fluoride-containing solutions, we can provide suitable wastewater treatment systems upon request.
Your benefits at a glance
- Effective removal of acidic pollutants - HCl, HF, HNO3, SO2, acetic acid, and more
- Compliance with strict environmental regulations - reliably reduces emissions
- Optimized process control - minimal chemical consumption, maximum efficiency
- Flexible customization - individually configurable to meet your requirements
- Complete solution - available with integrated wastewater treatment upon request
Efficient removal of sulfur trioxide and sulfuric acid aerosols
with high-performance filter candles
SO3 typically generates during the production and processing of sulfuric acid or in other high-temperature processes where sulfur compounds oxidize. In humid exhaust gases, SO3 reacts to form sulfuric acid aerosols. These finely dispersed droplets are highly corrosive, posing a significant risk to both the environment and downstream plant equipment.
Our specially designed separators equipped with filter candles offer a highly efficient solution for removing these aerosols from the gas stream - compact, reliable, and low-maintenance.
How does it work?
The aerosol-laden gas stream is routed through a vessel containing filter candles made of glass or synthetic fibers. Physical filtration occurs via a combination of mechanical interception, inertial impaction, and diffusion. This process reliably retains the aerosols on the filter surface, allowing them to be continuously drained.
Your benefits at a glance:
- Reliable separation of ultra-fine aerosols with collection efficiencies up to 99.99%
- Corrosion-resistant construction ideally suited for highly aggressive media
- Compact footprint perfect for retrofitting or integrating into existing systems
- Low maintenance costs thanks to long-lasting filter candles and easy handling
- High operational reliability even under fluctuating process conditions
Efficient hydrogen sulfide removal
clean air with our specialized gas scrubber
Hydrogen sulfide (H2S) in exhaust gases is both highly toxic and foul-smelling, requiring immediate, effective removal. Our high-performance packed-bed columns and cross-flow scrubbers provide reliable H2S removal, even under challenging conditions such as high CO2 concentrations in biogas.
How does it work?
H2S is effectively removed in the scrubber using caustic soda and hydrogen peroxide. While the caustic soda absorbs the hydrogen sulfide, the hydrogen peroxide ensures complete oxidation into environmentally compatible sulfates.
Thanks to our specially designed reaction tank, the process can also be operated at low pH values. This makes the system particularly suitable for exhaust gas streams with high CO2 content, such as those found in biogas plants.
Your benefits at a glance
- Effective H2S removal – reliable elimination of odors and pollutants
- Flexible application – also suitable for CO₂-rich exhaust gas streams such as biogas
- Optimized reaction control – can be operated even at low pH values thanks to the special reaction tank
- Individually adaptable – optimally tailored to your process conditions
Effective SiF₄ removal in an acidic two-stage system
safe and process-oriented
Silicon tetrafluoride (SiF4) is a highly reactive, corrosive gas that is generated in various industrial processes - particularly in glass and semiconductor manufacturing. Our two-stage absorption systems provide a reliable solution for the safe and efficient removal of SiF4.
How does it work?
The gas treatment process operates under acidic conditions using two packed-bed columns connected in series:
Column 1- Conversion to hexafluorosilicic acid (H2SiF6)
The SiF4-laden exhaust gas is absorbed in water. Through controlled dosing of hydrofluoric acid, SiF4 is fully converted into hexafluorosilicic acid. This prevents solid silica precipitation inside the column. The resulting hexafluorosilicic acid remains in solution and can either be reused (if sufficiently pure) or properly disposed of.
Column 2 - Residual gas treatment
Residual SiF4 and desorbed HF are reliably removed, while second-stage wastewater is recycled back to the first stage to minimize chemical use and waste.
Your benefits at a glance
- Reliable conversion of SiF4 through controlled HF dosing
- High operational safety thanks to two-stage treatment with recirculation
- Corrosion-resistant design - optimized for fluoride-containing media
- Optional recovery and further use of the produced H2SiF6 solution
Efficient nitrogen oxide removal
clean air, safe processes
Nitrogen oxides (NOx) are harmful air pollutants that contribute to the formation of smog and acid rain and are subject to strict emission limits. Our highly efficient NOₓ scrubbers ensure reliable reduction of nitrogen oxides and enable environmentally compliant exhaust gas treatment - individually tailored to your processes.
How does it work?
The contaminated exhaust gas stream is passed through one or a series of packed-bed columns. In these columns, the nitrogen oxides are absorbed into a washing solution and chemically converted using sodium hydroxide (caustic soda) and/or hydrogen peroxide. Depending on the process conditions, the reaction products are either sodium nitrate/sodium nitrite or nitric acid, which can be further utilized or safely disposed of.
Your benefits at a glance:
- High removal efficiency - reliable reduction of NO and NO2
- Single- or multi-stage scrubbing processes - oxidative methods for maximum efficiency
- Flexible customization - tailored solutions for a broad range of NOₓ concentration
- Cost-effective operation - optimized chemical consumption for low operating costs
- Compliance with legal requirements - safely below emission limits
