In livestock farms, air filters are key equipment for controlling air quality, reducing the spread of diseases, and improving the breeding environment. Its core function is to filter out dust, microorganisms (including bacteria, viruses, and fungal spores), ammonia/hydrogen sulfide, and other harmful gases and odors in the air, thereby ensuring the health of livestock and poultry, improving production efficiency, and reducing pollution to the surrounding environment. According to the filtration objectives and technical principles, the commonly used air filters in livestock farms are mainly classified into the following categories:
I. Classification by filtering object: Four core types
Particulate matter filter (mainly for dust removal)
It is mainly used to remove solid particles in the air, including feed dust, livestock and poultry dander, feathers, and dust raised after the drying of manure, among other substances. This type of dust not only irritates the respiratory tracts of livestock and poultry but also adsorbs microorganisms, becoming carriers of disease transmission.
Common types
Primary air filter
Material: Non-woven fabric, nylon mesh, metal mesh, coarse fiber filter paper.
Filtration efficiency: For large particles ≥5μm, the efficiency is approximately 30%-60% (by weight method).
Application scenario: As a pre-filter, it protects the subsequent medium and high-efficiency filters and extends their service life. It is often used for primary filtration at the air inlet of fans and the air inlet end of water curtains.
Medium-efficiency air filter
Material: Glass fiber, synthetic fiber (such as polyester fiber), non-woven fabric (high density).
Filtration efficiency: For particles ≥1μm, the efficiency is approximately 60%-95% (by colorimetric method).
Application scenario: It is used in farms with high requirements for dust control (such as broiler breeding farms and piglet nursery houses), installed after the primary filter to further reduce the concentration of fine dust.
High-efficiency air filter (HEPA)
Material: Superfine glass fiber filter paper, PTFE membrane (polytetrafluoroethylene).
Filtration efficiency: For particles ≥0.3μm, the efficiency is ≥99.97% (MPPS method), which can effectively retain most bacteria and viruses.
Application scenarios: Areas with extremely high biosecurity levels, such as breeding livestock and poultry isolation houses, vaccine production workshops, SPF (Specific Pathogen-free) livestock and poultry farms, or for terminal filtration of exhaust air to prevent pathogen leakage.
2. Microbial filter (mainly for epidemic prevention In addition to particulate filters, microbial filters address airborne pathogens, making them essential for disease control.
Caractéristiques techniques
It is usually combined with high-efficiency filtration (HEPA) or ultra-high-efficiency filtration (ULPA, with an efficiency of ≥99.999%@0.12μm) technology, and uses principles such as fiber interception, inertial collision, and diffusion deposition to capture microorganisms.
Some products will add antibacterial coatings (such as silver ions, nano zinc oxide) to inhibit the growth of microorganisms on the surface of the filter and prevent secondary pollution.
Application scenarios
Air intake filtration for the introduction isolation houses, farrowing houses, and nursery houses of breeding chickens/pigs;
Air circulation and filtration in the shed during the epidemic purification period.
Pathogen interception at the exhaust outlet of the breeding farm to prevent the spread of the epidemic to the surrounding environment.
3. Chemical filter (Deodorization + removal of harmful gases
Harmful gases such as ammonia (NH₃), hydrogen sulfide (H₂S), and volatile organic compounds (VOCs) in the air of livestock farms can cause stress and respiratory damage to livestock and poultry, and at the same time produce a strong odor. Chemical filters remove such substances through adsorption, absorption, or chemical reactions.
Common types
Activated carbon filter
Principle: Utilizing the porous structure of activated carbon to physically adsorb odor molecules and some harmful gases (such as H₂S and VOCs).
Features: Low cost, needs to be replaced regularly after adsorption saturation, suitable for scenarios with medium and low concentrations of odors.
Application: Auxiliary deodorization for the air outlet of the fan and the air circulation system inside the shed.
Chemical adsorption filter
Principle: Fill carriers impregnated with chemical agents (such as potassium permanganate, ferrous sulfate, sodium hydroxide) (such as alumina, silica gel), and through chemical reactions, convert NH₃, H₂S, etc. into harmless substances (for example, NH₃ reacts with sulfuric acid to form ammonium sulfate).
Features: Highly targeted, with a higher efficiency in removing harmful gases than ordinary activated carbon. It is suitable for scenarios with high concentrations of ammonia/hydrogen sulfide (such as near fattening houses and temporary storage rooms for manure).
Biological filter/biological filter
Principle: By taking advantage of the metabolic actions of microorganisms (bacteria, fungi), harmful gases (such as NH₃ and H₂S) are decomposed into CO₂, H₂O, and harmless salts.
Features: Environmentally friendly and sustainable (no frequent replacement of materials), but requires space and control of temperature and humidity to maintain microorganism activity.
Application: Centralized exhaust treatment systems for large-scale livestock farms or odor control in open manure and sewage treatment areas.
4. Combined air filter
In response to the complex air purification requirements of breeding farms (such as the simultaneous need for dust removal, microbial removal, and odor removal), multiple filtration functions are integrated into one to enhance purification efficiency and save installation space.
Common combination forms
Primary filtration + medium filtration + HEPA filtration (for dust and microorganisms, such as air intake in breeding livestock and poultry houses);
Primary filtration + activated carbon filtration (for dust and odors, such as exhaust from fattening houses);
Primary filtration + chemical adsorption filtration + biological filter (for dust + harmful gases + odors, such as centralized treatment systems in large-scale livestock farms).
Ii. Classification by installation location: Two major application scenarios
| Classification | Function | Common combinations of filter types | Typical applications |
| Air intake filter | Prevent external dust and pathogens from entering the shed | Primary efficiency + medium efficiency + HEPA (High biosafety) Primary efficiency + medium efficiency (ordinary breeding) | Air inlet of the fan, air inlet end of the water curtain |
| Exhaust filter | Medium-efficiency + HEPA (Epidemic Prevention) for preventing the leakage of pathogens and odors inside the shed | Primary efficiency + activated carbon/biological filter (deodorization) | The outlet of the fan and the end of the chimney |
Iii. Core Considerations for Selecting Air Filters in Livestock FarmsBreeding species and stages: Breeding livestock and poultry, as well as young livestock and poultry (such as piglets and chicks), have higher requirements for air quality and need to be equipped with HEPA-level microbial filters. For fattening livestock and poultry, emphasis can be placed on dust removal and odor elimination.
Biosafety level: In areas with a high incidence of diseases and livestock and poultry farms, it is necessary to enhance the microbial filtration of intake and exhaust air. Ordinary commercial livestock farms can be simplified to “primary efficiency + medium efficiency + activated carbon”.
Breeding scale and environment: It is recommended that large-scale breeding farms adopt centralized combined filtration systems. Small-scale livestock farms can choose individual filters (such as wall-mounted air purifiers).
Maintenance cost: It is necessary to balance the filtration efficiency and replacement cost (for example, HEPA filters are expensive but have a long service life, while activated carbon needs to be replaced frequently). Prioritize products that are easy to disassemble and replace.
Biosafety level: In areas with a high incidence of diseases and livestock and poultry farms, it is necessary to enhance the microbial filtration of intake and exhaust air. Ordinary commercial livestock farms can be simplified to “primary efficiency + medium efficiency + activated carbon”.
Breeding scale and environment: It is recommended that large-scale breeding farms adopt centralized combined filtration systems. Small-scale livestock farms can choose individual filters (such as wall-mounted air purifiers).
Maintenance cost: It is necessary to balance the filtration efficiency and replacement cost (for example, HEPA filters are expensive but have a long service life, while activated carbon needs to be replaced frequently). Prioritize products that are easy to disassemble and replace.
In conclusion, the selection of air filters for livestock farms should be comprehensively matched based on purification goals, breeding scenarios, and cost budgets. Through scientific combinations, multiple effects such as dust removal, disease prevention, odor elimination, and harm reduction should be achieved, ultimately ensuring the health of livestock and poultry and the benefits of breeding.
