Filtralite® Air Technology: A Breakthrough in Biofiltration for Odor-Free, Cleaner Air
Introduction
Air pollution remains one of the most pressing environmental challenges worldwide, especially in urban, industrial, and agricultural settings. Traditional air filtration systems often struggle with high costs, energy consumption, and limited long-term effectiveness. In response, Filtralite® Air emerges as an innovative and sustainable solution for biofiltration of polluted air.
What is Filtralite® Air?
Developed by Leca International, Filtralite® Air is a lightweight, porous filter media made from expanded clay aggregates. It is specifically engineered to support microbial activity that breaks down harmful airborne pollutants like hydrogen sulfide (H2S), ammonia (NH3), and volatile organic compounds (VOCs).
Its unique structure offers high surface area, excellent airflow, and strong water retention, making it ideal for use in biofilters and biotrickling filters. By enabling efficient odor control and air purification in wastewater treatment plants, agriculture, industry, and biogas facilities, Filtralite® Air represents a major step forward in the field of environmentally friendly air treatment technologies.
Odours are often results of a complex mixture of chemical compounds and the effect of dilution is different for various compounds, not only quantitatively but also qualitatively. Sources for odour can be manure, waste water plants, industry and waste fillings. Thus, Filtralite® Air is engineered to balance mechanical strength, water retention, and porosity.
Composition and Manufacturing Process
Filtralite® is produced by heating naturally occurring clay at temperatures exceeding 1100°C, causing it to expand and form lightweight granules with a hard outer shell and porous internal structure. Media Chemical Composition is Mainly alumino-silicates, with high structural stability. Moreover, pH Neutrality ensures compatibility with microbial life. This structure supports airflow with minimal resistance while providing a large surface area for biofilm attachment and microbial growth.
How Filtralite® Air Works: Mechanism of Biofiltration
The simple principle of treating odour is to pump the gas through a filter media upstream or downstream with water sprinkling.
• Upstream System: Polluted air is pushed upwards through the filter while sprinkling water drip downwards.
• Downstream System: Polluted air is pushed downwards through the filter together with sprinkling water.
Here’s a breakdown of the process:
• Initial Gas Contact
Polluted air is passed through a bed of moistened Filtralite® Air. The media captures and adsorbs water-soluble gases such as H2S and NH3.
• Biofilm Formation
A thin layer of water on the surface of the media supports the growth of bacteria, fungi, and other microbes. These microbes form a biofilm that metabolizes and degrades pollutants.
• Pollutant Degradation
– Hydrogen Sulfide (H2S) is oxidized to elemental sulfur or sulfate by sulfur-oxidizing bacteria (e.g., Thiobacillus).
– Ammonia (NH3) is converted to nitrites and nitrates by nitrifying bacteria.
– VOCs are broken down through enzymatic pathways, depending on their structure.
The moisture-retaining properties of Filtralite® ensure long term stability and activity of the microbial community.
Physical and Functional Properties of Filtralite® Air
• Type of Material: Expanded clay
• Appearance: Round particles, smooth surface
with micro pores
• Bulk Density: 250-360 kg/m³ (lightweight)
• Particle density: 430- 650 kg/m³
• External volumetric air content: 43%
• Water Retention: Porous structure holds water, enhancing trickling efficiency
• Chemical composition, approx. Values:
| SiO2 | 63% |
| Al2O3 | 17% |
| Fe2O3 | 7% |
| K2O | 4% |
| CaO | 2% |
| Na2O | 2% |
• Stable & Durable: Natural clay structure that won’t collapse – no hazardous or artificial additives.
• Lightweight: 5x less pressure on structures than ordinary materials = lower construction and removal costs.
• Porosity: highly porous structure
• Consistent Quality: Precisely graded for uniform particle size, ensuring predictable and reliable filtration performance.
• High Surface Area: Provides an ideal environment for biofilm growth, enhancing biological treatment efficiency.
• Excellent Permeability: Promotes smooth airflow with low pressure loss, contributing to energy efficiency and longer media lifespan.
• Water Retention Capacity: Porous structure
absorbs and holds water, improving trickling efficiency and supporting biofilm hydration.
• Early Odor Removal: Possesses natural sorption capacity for hydrogen sulfide (H2S), allowing odor reduction to begin even before biofilm is fully developed.
Applications and Use Cases
• Wastewater Treatment Plants (WWTPs):
Used in odor control units for sludge handling, aeration tanks, and headworks. Helps reduce
community complaints and improve regulatory compliance.
• Industrial and Chemical Plants:
Effective in treating exhaust from food processing, fertilizer production, and chemical reactors.
• Composting and Biogas Plants:
Filtralite® Air media is used in biofilters to treat gases from organic waste, significantly reducing odor and harmful emissions.
Filtralite® Air in Action: Case Studies and Practical implementations
1. Air purification at Novozymes Fermentation unit in Kalundborg (DK):
Novozymes faced issues with their old filter media:
High pressure drops, uneven water distribution, and high energy use. In 2005, engineer Anders P. Jensen found that Filtralite® Air was used successfully at other Danish plants. They replaced the old media with 350 m³ of Filtralite® Air 4–10, known for its large surface area (580 m²/m³) and low- ressure loss. To speed up biofilm formation, they mixed in some of the old media containing bacteria. Installation was quick using blower trucks (1 m³/min).
Results:
• Lower, stable pressure drop
• Better humidity control and air purification
• Increased capacity
• Saved 100,000 kWh/month
After 5 years, the media remained effective and stable.
2. Odour treatment filter in Bogense biogas plant (DK):
Leca Danmark A/S supplied 750 m³ of Filtralite® Air 10–20 mm for odor treatment.
• The media’s 40–45% porosity allows efficient air distribution and low pressure drop, saving energy.
• Its porous surface supports biofilm growth and effective odor removal without clogging.
• The system treats 40,000 m³ of air per hour, with bacteria forming naturally within weeks to break down odor compounds.
Compared to bark-based filters, Filtralite® Air:
– Holds moisture better
– Remains structurally stable
– Saves up to 60% water annually
Lifespan: 8–10 years without replacement.
The Bogense plant produces 10 million m³ of biogas/year, supplying 6,000 homes with heat.
Conclusion
As air pollution continues to impact human health and the environment, the need for effective, sustainable purification technologies has never been greater. Filtralite® Air offers a powerful solution by combining the natural advantages of expanded clay with modern biofiltration principles.
Its high porosity, moisture retention, and microbial support enable efficient removal of harmful gases such as H2S, NH3, and VOCs, while its lightweight and stable structure reduces operational and maintenance costs. With proven success in real-world applications—like the Novozymes plant in Denmark and Bogense biogas plant (DK) —Filtralite® Air stands out for its long-term durability, energy efficiency, and odor control performance.
In a world demanding cleaner air and greener technologies, Filtralite® Air is not just a filter media—it’s a smart investment in the future of sustainable air purification.
Mohammed Kastawy
Area Sales Manager – MENA Region
Mobile: +971565503535
Email : mohammed.kastawy@saint-gobain.com
LinkedIn: www.linkedin.com
