Municipal waste and sewage

Municipal waste and sewage has so far seen nitrogen as a cost and challenge to get rid of without creating harmful pollution. The use of acidic nitrates and nitrite will change this to become a business opportunity. One sewage plant is already using nitric acid to recover ammonia from the final waste water and return ammonium nitrate to fertilizer industry.

Sewage treatment plant

Sewage treatment plant
The nitrogen content in the sewage is exposed to aeration and biological nitrification and de-nitrification.
The surplus of ammonia is seen as a main bottleneck and potential pollutant

Municipal waste and sewage contains nitrogen in the form of ammonia, urea and protein.  As long as the nitrogen is not seen as a valuable nutrient, it is becoming a capacity limitation and potential pollutant.

The free ammonia Nitrogen is stripped off using air in the first part of the sewage handling.  In this process the two mechanisms are a direct loss of ammonia to air and nitrification de-nitrification process.  For both alternatives the ammonia ends up as acidic rain, N2O and N2.

The Nitrogen which is not stripped off by air, is ending up in the effluent water from the frontend of the plant, and or is fed to the bio-gas reactor as part of the solid part of the waste stream.  In the biogas reactor the biological degradation is releasing more free ammonia, and this ammonia will follow the liquids back to the feed where it is supposed to be stripped off again.The alternative to recycling the ammonia to the feed stream is to strip off the ammonia and absorb it an acidic nitrate solution.  The benefit of using acidic nitrate as an absorbent is that the product is getting the full value as a pure commercial nutrient.

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