Fixing nitrogen, recovering valuable materials
Chemical air scrubbing is used to capture emissions containing ammonia. This often produces ammonium sulfate solution, or ASS for short. Typical fields of application include fermentation residue treatment in biogas plants, sludge treatment, and industrial drying and processing methods, in which ammonia emissions must be safely reduced. ASS contains nitrogen and sulfur and is therefore a valuable source of nutrients. The real challenge starts after the chemical air scrubbing, with the formation of a liquid intermediate product that requires storage and must be processed further without compromising its quality. The plant owner must therefore ask themselves how they can reliably convert ASS into a marketable fertilizer.
Valuable, but problematic
As a liquid, ASS is difficult to handle. Storage can impose special requirements on tanks, pipes, and operational reliability depending on the concentration, pH value, and composition. In addition, fluctuating quality levels and differing nitrogen contents make direct use or marketing difficult. Especially in situations where storage capacity is low or larger quantities of ASS are produced, this liquid quickly becomes a financial and logistical issue. Instead of specifically feeding nutrients back into the cycle, additional costs are incurred for temporary storage, transportation, and quality assurance. As a result, the benefits of the nutrients it contains can often only be harnessed to a limited extent.
The solution: Refinement into a solid fertilizer
In order to be able to use ASS profitably, it must be converted into a stable form that is easy to handle. This is where Terrawater ASL comes in: The ammonium sulfate solution is thermally concentrated and crystallizes into sulfuric acid ammonia – a solid nitrogen and sulfur fertilizer. The conversion into a solid yields a high-quality fertilizer from the qualitatively ambiguous ammonium sulfate solution. Because sulfuric acid ammonia is much lighter than ASS and also dry, it can be stored much more easily and transported for longer. The substance can therefore be integrated better into existing nutrient and marketing concepts. At the same time, available heat from technical processes can be used, meaning that processing can be incorporated into existing plant environments in an energy-neutral manner, which in turn saves resources.
More flexibility in nutrient management
The crystallization of ASS frees up storage capacity and makes it much easier to plan handling of the fertilizer. So, instead of having to handle liquid ASS as a problematic intermediate product, the result is a solid fertilizer of consistent quality that can be stored. Terrawater ASL therefore contributes to resource recovery efforts: Nitrogen and sulfur remain in the cycle, emissions requirements go hand-in-hand with financial benefit, and a challenging material flow is turned into a marketable product.
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