Biofiltration is an air pollution control technology which utilizes microorganisms to biologically degrade hydrogen sulfide (H2S) odors and other volatile air pollutants such as ammonia, amines, mercaptans, dimethyl sulfides, dimethyl disulfides and others, contained in waste air streams.
The reason why Bioteg has specialized in biofiltration rather than in any other H2S odor and air pollution control technology, such as biotrickling filters, carbon adsorbers or chemical scrubbers, is that our experienced staff is convinced of the many advantages that come with the biofiltration technology:
Biofiltration is an easy and cost effective technology.
Biofiltration is a very forgiving process that is not easily upset, even at times of high spikes or low concentrations.
Biofiltration is therefore very reliable and requires very little maintenance.
Biofiltration consumes a minimal amount of water and electricity, and has no need for additional nutrients.
Biofiltration can provide odor removal at 99% efficiency.
Bioteg’s organic, nontoxic and biodegradeable filter material has a life span of up to 7 years and is non-hazardous even when it is spent.
Biofilters have a low capital investment cost and even lower long-term operating costs.
Bioteg Biofilter Material
Bioteg has developed a very effective organic biofilter material (Bioteg bps BT-50/100) based on shredded pine roots. Due to the natural tanning agents in the roots, this filter material is extremely stable and alters its physical and microbiological properties only slightly over time. (Plants produce tanning agents to protect their roots from degradation in the soil during their lifetime.) There is very little long term compaction of the filter bed. This stable structure results in a low pressure-drop providing for extremely low energy consumption.
Our special preconditioning procedure increases the media’s surface area, which is populated by microorganisms, resulting in a very high odor and hydrogen sulfide (H2S) removal efficiency.
Two different types of Bioteg bpc-Biofilter Material are available
Bioteg bpc-BT50
(appropriate for our small biofilters)
Bioteg bpc-BT100
(appropriate for large biofilter systems)
Our compact biofilters are filled with a mixture of Bioteg bpc-BT50 and bpc-BT100.
The lifetime of Bioteg’s organic bps Biofilter Material spans between 3-7 years.
The spent biofilter is non-hazardous and can be easily composted or disposed of at a landfill.
Bioteg bpc Biofilter Material: Physical Properties
| Dry Weight | approx. 120 kg/m3 | approx. 7.5 lbs/cft |
| Operational weight (humidified) | approx. 180 - 365 kg/m3 | approx. 11-25 lbs/cft |
| Maximum water retention capacity | approx. 270 kg/m3 | approx. 17 lbs/cft |
| Pressure drop at filter area load of 150 m3/m2 | < 1 mbar (100 Pa)/m) | < 0.4 in wc |
Biofiltration Air Pollution Control Technology
Biofiltration Process
Biofiltration is an air pollution control technology that utilizes microorganisms to biologically degrade odors and other volatile air pollutants contained in waste air streams. The microorganisms exist on the surface and in a thin water film surrounding the surface of the biofilter material. During the biofiltration process, the contaminated air is slowly pumped through the biofilter material.
The pollutants are adsorbed by the filter material’s surface and absorbed into the water film. Simultaneously, the microorganisms biologically consume i.e. metabolize the pollutants, producing energy, biomass, and metabolic end products, mainly CO2 and H2O. The biofiltration process results in a complete decomposition of the pollutants without creating hazardous byproducts.
Biofilters
Biofilters are technical applications that use the biofiltration process to remove odorous compounds and other air pollutants like volatile organic compounds (VOC) from waste air. The name “biofilter” may be confusing by the imagination of normal filters which simply separate pollutants from fluids or gases.
In a biofilter, the pollutants are “consumed” by the microorganisms and degraded into biomass, water, and CO2. This allows the filter material to continuously regenerate itself. The term bio-catalyst or bio-reactor would therefore be more suitable, however, the name biofilter is commonly accepted and used.
Biofilter Design
The easiest design of a biofilter is the age-old practice of covering landfills with soil. The odorous air rises through the layer of soil where microorganisms degrade the odorous compounds.
However, to plan, design, and build a biofilter that will continuously run reliably, it takes technical and microbiological expertise and experience. A crucial prerequisite for the successful functioning of a biofilter is the creation and maintenance of suitable physical and chemical conditions for microorganisms to thrive. This includes maintaining the right temperature, moisture, pH-value, and amount of nutrients.
Bioteg Biofilter Systems Consist Of The Following Key Components:
Ventilator
Air humidifier
(with integrated heating, if necessary)
Air distributor
Filter material
Control panel
Biofilter Applications
Biofilters can be applied on any biologically degradable odor and air pollutants and are commonly employed in the water and wastewater industry for the removal of hydrogen sulfide (H2S), mercaptans, dimethyl sulfides, dimethyl disulfides, and ammonia.
Biofilters Can Be Deployed At Multiple Locations & Industries:
Main Definitions and Parameters
| Definition | Description | Dimension |
|---|---|---|
| Odor Unit | Dilution at which 50% of a test panel recognize a smell | non-dimensional |
| Empty Bed Residence Time (EBRT) | Time the air spends in the empty reactor (V/Q) | min |
| Filter Surface Load | Airflow / filter area (footprint) (Q/A) | m3/m2h |
| Volumetric Load | Airflow / filter volume (Q/V) | m3/m3h |
| Mass Loading Rate | Mass of contaminant per area or volume of filter material (Q x Cin) / A (Q x Cin) / V | g/m2 g/m3 |
| Removal Efficiency | Describes the performance of the system: 100 x (Cin-Cout) / Cin | % Removal |
Biochemical Functions
Chemical Degradation Reactions (Simplified)
The three main groups of odorous compounds are carbon-, sulfur- or nitrogen-based. The most important reaction of the degradation of these compounds is their oxidation to CO2, SO42- and NO3- and their assimilation into biomass. At times of reduced input concentrations, microorganisms can also assimilate nitrates (NO3) and sulfates (SO42-) into biomass.
Biofilters that are loaded with high concentrations of organic substances may have a shorter lifespan because the additional biomass growth might consume more of the filter matrix.
Therefore, the lifetime of Bioteg’s organic biofilter material spans between 2 and 7 years