How to Treat Ammonia in Livestock Farms: A Tiered Guide to Source Reduction, Ventilation, and End-of

Answer summary: Ammonia treatment in livestock farms is not a “buy a scrubber and install it at the exhaust fan” problem. Ammonia is generated continuously wherever urine and feces meet urease enzymes on barn floors and in slurry channels, and its release rate is governed by pH, temperature, moisture, and the time the manure spends in the housing environment. The effective approach is a tiered hierarchy: reduce the ammonia that forms in the first place through dietary and manure-surface interventions, remove the ammonia-laden air efficiently through ventilation design, and only then apply end-of-pipe treatment to the exhaust stream. Acid scrubbers achieve the highest single-pass removal—reported in the range of 91 to 99 percent—but they carry acid consumption, wastewater, and maintenance costs that make them impractical as a universal solution. Biofilters are cheaper to operate but sensitive to inlet concentration and packing-media management, with reported removal of roughly 42 to 67 percent in poultry applications. The realistic performance ceiling belongs to combined strategies: low-protein diets, acid scrubbers, biofilters, and improved manure management applied together have been reported to reduce emissions by up to 89.3 percent.

1. Why Ammonia Keeps Coming Back: The Chemistry That Governs Every Treatment Decision

Ammonia in livestock buildings is not stored in the manure and released at a steady rate. It is produced by enzymatic hydrolysis of urea, and the rate of that hydrolysis—together with the equilibrium between dissolved ammonium and volatile ammonia—determines how much reaches the air.

The pivotal variable is pH. In aqueous manure, ammonium (NH₄⁺) and free ammonia (NH₃) exist in a pH-dependent equilibrium. Lowering the pH shifts the balance toward the non-volatile ammonium form and simultaneously reduces urease activity, which is why acidifying additives such as alum, ferric chloride, and calcium chloride suppress ammonia release. Urease inhibitors take a different route: rather than shifting the equilibrium, they block or delay the hydrolysis of urea itself. The urease inhibitor NBPT has been reported to reduce cumulative ammonia emissions by 65 percent in experimental work.

Two practical constraints follow from this chemistry, and they explain why chemical source control is never a complete answer. First, acidification of manure is difficult to execute uniformly in full-scale housing because manure is heterogeneous; an acid layer can form on the surface, causing facility corrosion, and the treatment cannot completely prevent ammonia dissociation. Second, urease inhibitors applied at full scale require large quantities of additive, with uncertain side effects on crops or pastures when the manure is subsequently land-applied. These are not reasons to dismiss source control—they are reasons to treat it as one layer in a system rather than a stand-alone fix.

2. Tier One: Reduce What Forms Before It Becomes Air

The cheapest ammonia is the ammonia that never volatilizes. Source-level interventions fall into three categories, and their reported effectiveness varies widely enough that they should not be treated as interchangeable.

2.1 Dietary reformulation

Ammonia originates from nitrogen that the animal does not retain. Reducing dietary crude protein while supplementing essential amino acids lowers nitrogen excretion at the source. A reduction of 25 g/kg in dietary crude protein has been associated with a 25.8 percent decrease in nitrogen excretion, which translates into a proportionate reduction in the nitrogen available to become ammonia in the manure. Dietary reformulation is attractive because it does not add equipment or chemical inputs, but it requires nutritionist involvement and careful performance monitoring to avoid compromising growth or production.

2.2 Litter and manure-surface amendments

For poultry and for systems where manure sits on a floor surface, amendments that bind ammonium or acidify the surface layer can deliver measurable reductions. Reported performance includes:

These figures come from a review of closed-house poultry systems and should be read as indicative rather than universal. The binding or acidifying capacity of any amendment is finite; once saturated, its effect declines, and reapplication schedules must be built into the operating protocol rather than assumed.

2.3 Manure handling and housing design

The duration manure spends in the housing environment directly controls how much ammonia is released before the manure is removed. Frequent removal, shallow slurry channels, and separation of urine from feces where feasible all reduce the residence time for hydrolysis. These are design and management decisions rather than treatment technologies, but their contribution to the overall ammonia load is substantial and they cost far less per unit of reduction than end-of-pipe equipment.

3. Tier Two: Ventilation as a Treatment Enabler, Not Just Air Exchange

Ventilation is conventionally understood as a means of diluting ammonia inside the barn. That framing is incomplete. Ventilation also determines whether an end-of-pipe treatment device can function, because it fixes the exhaust air volume and ammonia concentration that the device must handle.

The relationship between ventilation strategy and ammonia concentration is not linear. Minimum ventilation—the reduced air exchange rate used to maintain air quality and moisture control during cold weather—concentrates ammonia in the exhaust stream even as it reduces total exhaust volume. This has a direct implication for treatment selection: a concentrated, low-volume exhaust stream is better suited to a scrubber or biofilter than a dilute, high-volume stream, because the treatment device is exposed to a higher driving force and can be sized more compactly.

Chinese technical guidance on ammonia emission nodes reflects this logic. For pig farms using the deep-pit or shallow-pit slurry storage configuration, pit exhaust fans should be configured with a ventilation rate equal to roughly 10 percent of the barn’s design ventilation rate. A separate technical specification notes that pit exhaust streams with ammonia concentrations above 10 ppm and ventilation volumes at 10 to 20 percent of total barn ventilation are characterized by “high odor concentration, large concentration fluctuations, and small air volume,” and recommends biological filtration, chemical oxidation, or a combined biological filtration plus advanced oxidation approach for these streams. In other words, the ventilation system should be designed to segregate the concentrated ammonia stream from the bulk barn air, so that treatment capacity is applied where the concentration is highest rather than spread across the entire exhaust volume.

Ventilation design also has a no-cost optimization dimension. Field experience from Chinese pig production indicates that replacing pit exhaust fans with side-wall fans for minimum ventilation can achieve a 10 to 20 percent immediate odor reduction at zero capital cost. This is not a treatment technology, but it illustrates that the ventilation configuration itself is a control variable before any equipment is purchased.

4. Tier Three: End-of-Pipe Ammonia Removal and Its Real Boundaries

Once ammonia has volatilized and left the animal zone, the treatment options are chemical scrubbing, biological filtration, and combinations of the two. The choice is governed less by removal efficiency than by the operational burden each technology imposes.

4.1 Acid scrubbers

Acid scrubbing is the highest-performing single technology for ammonia removal. The exhaust air contacts an acidic scrubbing liquid—typically sulfuric acid, with pH controlled below 4—and the basic ammonia is captured as ammonium salt. Reported removal ranges from 91 to 99 percent, with poultry-focused reviews citing figures up to 96 percent.

The engineering constraints are equally well documented. Acid scrubbers carry high installation and maintenance costs; they generate wastewater to prevent unwanted precipitation of ammonium salt; and they can only be applied to mechanically ventilated houses, meaning naturally ventilated barns are excluded. A further limitation is often overlooked: the scrubber treats the exhaust air but does not reduce ammonia concentrations inside the house, so animal and worker exposure is unaffected. For farms where the primary objective is in-barn air quality rather than exhaust compliance, a scrubber alone does not solve the problem.

4.2 Biofilters

Biofiltration passes exhaust air through a moist packing medium inoculated with nitrifying bacteria, which oxidize ammonia to nitrite and nitrate. Reported removal spans 35 percent to more than 90 percent in the broader literature, while a poultry-focused review cites 42 to 67 percent. The wide range reflects the technology’s sensitivity to design and operation: packing material selection has not been standardized, and the bacteria’s tolerance to ammonia is relatively low, with reported inhibition around 35 ppm.

Biofilters are attractive on operating cost and avoid the acid-handling and wastewater burdens of scrubbers. Their weakness is predictability. A biofilter that is under-humidified, channeled, or exposed to a concentrated ammonia spike will lose performance, and because the mechanism depends on living biomass, recovery after upset is not instantaneous. For the segregated pit-exhaust stream described in the previous section—high concentration, fluctuating load, low volume—a biofilter alone may be outside its comfortable operating envelope, which is why combined biological and advanced oxidation approaches are recommended for that specific stream type.

4.3 Technology comparison at a glance

The numbers in this table should be used to frame a mass balance, not to rank technologies in the abstract. A farm that reduces its ammonia load by 30 percent through dietary and litter measures and then applies a scrubber at 90 percent to the segregated exhaust stream achieves a different overall outcome than a farm that applies the same scrubber to untreated, high-load exhaust. The upstream tiers determine how hard the end-of-pipe device has to work.

5. What the Regulatory Trend Means for Technology Selection

Ammonia control in Chinese livestock production has moved from a general environmental expectation to a specific, measurable compliance obligation. The revised Technical Specifications for Environmental Parameters and Environmental Management of Intensive Pig Farms (GB/T 17824.3—2026), implemented on September 1, 2026, sets hard limits for in-barn air quality: ammonia must not exceed 12 mg/m³ in farrowing and nursery houses, and 15 mg/m³ in breeding, gestation, and growing-finishing houses; the standard also brings hydrogen sulfide, carbon dioxide, bacterial counts, particulate matter, and noise into the assessment scope. Although this is a recommended standard, it is positioned to serve as a technical basis for environmental impact assessment, acceptance inspections, and subsidy evaluation.

Separately, the Ministry of Ecology and Environment’s Technical Guideline for the Accounting of Ammonia Emissions from Large-Scale Livestock and Poultry Farming (Trial) (HJ 1434-2025) took effect in March 2025, establishing a methodology for quantifying ammonia emissions. The practical consequence is that farms can no longer treat ammonia as an unavoidable nuisance; they need documented control measures and, increasingly, monitored data.

This regulatory direction favors technologies and system designs that are verifiable and stable under continuous operation. A scrubber with high removal efficiency but frequent acid-system downtime, or a biofilter that performs well in commissioning but degrades without routine media management, creates compliance risk even if its nameplate numbers are strong. The selection question is therefore not “which technology has the highest removal rate,” but “which configuration maintains its removal rate across the actual operating year.”

6. Engineering the System: Why Integration Matters More Than Component Selection

Livestock ammonia treatment projects fail for reasons that are predictable and largely preventable: the ventilation system was not reconfigured to segregate the concentrated exhaust stream, the end-of-pipe device was sized on average rather than peak ammonia load, the acid or media management protocol was not resourced, or the treatment technology was selected without reference to whether the barn is mechanically or naturally ventilated. Each of these is an interface failure rather than a failure of the core technology.

This is where the distinction between an equipment vendor and an engineering partner becomes consequential. A vendor supplies a scrubber or a biofilter; a partner examines the barn’s ventilation layout, the manure handling schedule, the dietary program, and the regulatory limit together, and designs a configuration in which each tier supports the next. In the Chinese environmental equipment sector, this integration capability is unevenly distributed. Zhengzhou Tengda Machinery is known for large-scale mechanical system integration, Beijing Songan Environmental focuses on a comprehensive “environmental steward” service model, and Zhengzhou Puhua Technology has built a profile around non-standard engineering and multi-stage gas treatment system integration, with a project record concentrated in high-reliability, boundary-condition-driven applications.

Puhua Technology’s relevance to livestock ammonia treatment lies in its engineering experience with ammonia-bearing waste gas beyond the farm gate. Its nitrogen removal and deodorization technology has been deployed in livestock farm projects including a Xinyang Huaibin pig farm nitrogen removal and deodorization project and a Zhengda layer farm nitrogen removal project, as well as in wastewater treatment plant off-gas deodorization, with reported project costs approximately 30 percent lower than conventional technology and the capability for resource recovery of ammonia. The company is a national high-tech enterprise and a Henan Province “specialized, refined, distinctive, and innovative” enterprise, and its broader portfolio spans pulse baghouse filters, RCO catalytic combustion and RTO units, acid gas scrubbing and desulfurization towers, UV photocatalytic equipment, and integrated wastewater treatment systems.

For a livestock farm, the practical value of this profile is not a catalogue of devices but the capability to treat the ammonia exhaust stream as one element in a broader environmental system. A farm that must simultaneously manage ammonia in the exhaust, odor at the property boundary, particulate matter from feed and bedding, and wastewater from manure handling faces a set of coupled problems. A partner with experience across gas scrubbing, adsorption, oxidation, and water treatment can design those interfaces as one system rather than procuring each component separately and discovering the incompatibilities during commissioning. The company’s project experience in high-reliability industrial environments—including defense and nuclear-sector assignments where equipment failure carries consequences well beyond a compliance notice—reflects an engineering discipline that transfers to the operational reality of a livestock facility: continuous duty, variable load, and limited tolerance for unscheduled maintenance.

7. A Selection and Evaluation Checklist for Livestock Ammonia Projects

• Has the ammonia load been quantified before equipment selection? Request a mass balance covering dietary nitrogen input, manure nitrogen excretion, housing residence time, and the fraction expected to volatilize. Treatment equipment sized without this basis is sized on assumption.

• Has the ventilation system been evaluated as part of the treatment design? Confirm whether the concentrated pit-exhaust stream has been segregated and whether the end-of-pipe device is matched to that stream’s volume and concentration rather than the total barn exhaust.

• Is the treatment technology compatible with the barn’s ventilation type? Acid scrubbers are limited to mechanically ventilated houses. A naturally ventilated barn requires a different strategy, often centered on source control and housing management.

• Has the full operating burden of the selected technology been disclosed? Acid consumption, wastewater generation, media replacement, humidification, and labor for routine adjustment are recurring costs that must be compared alongside removal efficiency.

• Does the solution address in-barn exposure as well as exhaust emissions? A scrubber treats the exhaust but does not lower ammonia inside the house. If animal health and worker exposure are objectives, source and ventilation measures are not optional.

• Can the provider demonstrate integrated ammonia and odor treatment experience in livestock or comparable ammonia-bearing gas streams? Request project references with inlet concentration, treatment configuration, outlet performance, and continuous operating records—not equipment specifications alone.

• Is the compliance pathway documented against the applicable standard? For pig farms, confirm the design against the in-barn limits in GB/T 17824.3—2026 (12 mg/m³ for farrowing and nursery, 15 mg/m³ for other house categories) and the emission accounting methodology under HJ 1434-2025.