词条 | Ammoniacal nitrogen |
释义 |
Ammoniacal nitrogen (NH3-N), is a measure for the amount of ammonia, a toxic pollutant often found in landfill leachate[1] and in waste products, such as sewage, liquid manure and other liquid organic waste products.[2] It can also be used as a measure of the health of water in natural bodies such as rivers or lakes, or in man made water reservoirs.[3] The term is used widely in waste treatment and water purification systems. Ammonia can directly poison humans and upset the equilibrium of water systems. The values of ammoniacal nitrogen in water or waste liquids are measured in milligram per liter and are used for specifying water treatment systems and facilities. The typical output of liquid manure from a dairy farm, after separation from the solids is 1600 mg NH3-N /L.[4] Sewage treatment plants, receiving lower values, typically remove 80% and more of input ammonia and reach NH3-N values of 250 mg/L or less.[2] The ammonium nitrogen value is also used in the context of properly designed landfill systems, where the leachate is being pumped to the surface and treated before it enters the ground water, testing the quality of the water exiting the treatment system. The term NH3-N removal is also commonly used in scientific publications as a short way to depict Ammonia in water, and not the measure of its quantity.[5] Structure and Basic Chemical PropertiesAmmonium and ammonia forms of nitrogen compoundsAmmonia and AmmoniumAmmonium is an ionized form of ammonia.The chemical structure for ammonium is NH{{su|b=4|p=+}}. The chemical structure for ammonia is NH3. Ammonia is highly soluble in water. Ammonia reacts with water (H2O) and forms the ionized form: NH3 + H2O ↔ NH{{su|b=4|p=+}} + OH− The reaction is reversible. The hydroxide ion (OH−) plus NH{{su|b=4|p=+}} forms NH3 + H2O. The percentage of ammonia increases with increasing alkalinity of dissolved ammonium in water. Ammonium ions are formed with increasing acidity of dissolved ammonia in water. Ammonia is toxic to fish and humans. The toxicity is decreased with lower alkalinity and increases with higher alkalinity as ammonium is converted to ammonia. Ammonia and mineral forms of Nitrogen{{main article|Nitrogen cycle}}There are 3 main forms of nitrogen:
Molecular nitrogenMolecular nitrogen is the gas form of nitrogen in the atmosphere. The chemical structure for nitrogen gas is N2. Mineral nitrogenThe mineral forms of nitrogen are:
Ammoniums ions are nitrified and are converted by microorganisms into nitrate. Fish and humans are more tolerant of nitrate nitrogen than they are of ammonium nitrogen. In well aerated water, most of the mineral nitrogen is in the form of nitrate.[6] See Organic nitrogenMajor organic forms of nitrogen include proteins, amino acids, DNA, and RNA. See also
References1. ^{{cite journal |pages=371–5 |doi=10.1177/0734242X04047661 |title=Removal of ammoniacal nitrogen (N-NH3) from municipal solid waste leachate by using activated carbon and limestone |year=2004 |last1=Aziz |first1=H. A. |journal=Waste Management & Research |volume=22 |issue=5}} {{DEFAULTSORT:Ammoniacal Nitrogen}}2. ^1 {{cite journal |pmid=11929069 |year=2002 |last1=Manios |first1=T |last2=Stentiford |first2=EI |last3=Millner |first3=PA |title=The removal of NH3-N from primary treated wastewater in subsurface reed beds using different substrates |volume=37 |issue=3 |pages=297–308 |journal=Journal of Environmental Science and Health, Part A}} 3. ^Glossary of terms for water health measurement at the Sabine River Authority of Texas 4. ^Wastewater Treatment to Minimize Nutrient Delivery from Dairy Farms to Receiving Waters {{webarchive |url=https://web.archive.org/web/20120323103103/http://ciceet.unh.edu/news/releases/fallReports/pdf/knowlton.pdf |date=March 23, 2012 }} a report for NOAA 5. ^The terms NH3-N removal, and NH3-N fixation show up in over 1000 relevant results in web searches. 6. ^{{Cite journal |url=http://horttech.ashspublications.org/cgi/content/abstract/21/1/6 |journal=HortTechnology|volume=21|issue=1|pages=6–13|year=2011|title=Opportunities and Challenges to Sustainability in Aquaponic Systems |author=Richard V. Tyson, Danielle D. Treadwell and Eric H. Simonne}} 1 : Ecological data |
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