OTAR has more than 20 years of operational experience and proven installations across Asia. Its five-variant architecture ensures there is a suitable ammonia recovery system for every US facility, regardless of waste heat availability, ammonia load or product market.

Why OTAR Uses Five Different Configurations

Understanding OTAR begins with its modular design. Unlike single-purpose ammonia treatment systems, OTAR adapts to the site instead of forcing the site to adapt to the technology.

OTAR serves a wide range of industries. These include biogas developers, CAFOs, municipal WWTPs, food processors and landfill operators. One of the five variants is designed for each application.

Variant 1

Waste Heat with Thermal Destruction

Variant 2

Waste Heat to Recover Ammonium Hydroxide

Where product recovery is desired, OTAR Variant 2 uses waste heat to strip ammonia and then absorbs the recovered gas into water, producing ammonium hydroxide (aqueous ammonia, typically 20–25% NH₃).

This is the preferred configuration for most UK and European markets, and it is gaining traction with US industrial processors as well. The process uses no acid and generates no salt waste, making the product eligible for OMRI listing — a certification that conventional acid-absorption systems cannot achieve.

One documented example involves a chemical manufacturing plant that integrated this variant to generate ammonium hydroxide for its own processes, reducing external purchases by nearly a third. With further concentration, the same system can produce anhydrous ammonia for fertilizer, refrigeration or hydrogen carrier applications.

This configuration suits AD and biogas developers and industrial processors who want to reuse or sell a high-purity, OMRI-eligible product without managing acid or salt byproduct.

Variant 3

Waste Heat to Recover Ammonium Sulphate

In agricultural regions with strong local demand for sulfate fertilizer, OTAR Variant 3 reacts the stripped ammonia gas with sulfuric acid to produce ammonium sulfate — either as a liquid fertilizer or crystalline solid. This pathway has proven particularly attractive where farming cooperatives can take the product directly and where sulfuric acid is readily available at competitive cost. The advantage is a stable, widely recognized product with established markets. The challenges are the need for a reliable acid supply chain and the requirement to meet agricultural quality standards. This variant does not produce OMRI-eligible product.

This pathway is a natural fit for dairy and swine CAFOs and agricultural regions where a farming cooperative or nearby growers can take ammonium sulfate directly as a nitrogen fertilizer, turning a manure management cost into farm revenue.

Variant 4

Heat Recycling

For sites without reliable waste heat, Variant 4 uses electricity to power a heat recycling system. The system compresses and recycles steam to generate the thermal energy needed for ammonia stripping.

The coefficient of performance exceeds 15 — meaning 15 or more units of stripping heat are delivered per unit of electrical energy consumed. This is highly efficient. Variant 4 is compatible with all product pathways: it can support thermal destruction, ammonium hydroxide production, anhydrous ammonia production or ammonium sulfate generation depending on the absorption stage selected. It is particularly suited to remote sites, standalone plants, and facilities with fluctuating waste heat availability such as seasonal food processors.

This makes Variant 4 a strong match for high-protein food & beverage processors with fluctuating production schedules, as well as remote AD sites and standalone CAFO digesters that lack a reliable waste-heat source.

Variant 5

pH-Driven Conversion

Where waste heat is in short supply, ammonia stripping can be facilitated by raising the pH of the wastewater to around pH 11 using an alkali base such as lime or sodium hydroxide (soda ash). At elevated pH, the equilibrium shifts toward free ammonia gas without requiring high temperatures, enabling stripping at ambient or moderately elevated conditions. Where some heat is available alongside pH adjustment, the chemical requirement can be proportionally reduced. This variant is fully compatible with all OTAR product recovery routes and is suited to sites where bulk chemical supply is straightforward. The trade-offs are the ongoing alkali cost and the need to adjust pH back after stripping for discharge compliance.

This variant suits sites — including many CAFOs and food processors — where bulk chemical (lime or caustic) supply is straightforward and a lower-capital, chemically driven approach is preferred over investing in waste heat recovery.

Which Ammonia Recovery System Variant Fits Your Facility?

Use this quick-reference guide to identify the OTAR configuration most likely to fit your site’s energy availability, ammonia load and product market:

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