The most concerned forms of nitrogen in water and wastewater are nitrate ammonia, nitrite nitrogen, ammonia nitrogen and organic nitrogen. Through biochemical action, they can be transformed into each other. Ammonia nitrogen digestion process-luheng
According to the "Surface Water Environmental Quality Standards" (GB 3838-2002) issued by the Ministry of Ecology and Environment of the People's Republic of China, it is stipulated that the concentration of ammonia nitrogen in surface water of category III is ≤1mg/L. The "Integrated Wastewater Discharge Standard" (GB8978-1996) stipulates that the general pollutant discharge unit ammonia nitrogen discharge ≤15mg/L (first-level discharge standard), ≤25mg/L (secondary discharge standard).
So how to quickly determine the ammonia nitrogen content in water? The following introduces two national standard methods with simple operation and accurate data. No professional knowledge is required, and the results can be detected very well.
1. Salicylic acid method (HJ 533-2009);
Detection principle: In the presence of alkaline medium (pH =11.7) and sodium nitroferricyanide, ammonia and ammonium ions in water react with salicylate and hypochlorite ions to form blue compounds.
Operation process: Take a clean colorimetric tube, add the water sample to be tested to the 15mL scale line of the tube, add a package of ammonia nitrogen reagent (I), cover the lid and shake to dissolve, after 2 minutes, add a package of ammonia nitrogen reagent II ), close the lid and shake to dissolve it, leave it for 15 minutes, open the lid, and place the colorimetric tube on the colorimetric card. The upper blank space is compared with the standard color scale from top to bottom, and the color of the solution in the tube is the same The color scale is the content of ammonia nitrogen in the water (mg/L).
Application industry: The salicylic acid method can detect sea water because of its low detection limit. It is widely used in aquaculture, aquarium, marine park, underwater world, domestic fish tank and ornamental fish water detection.
2. Nano reagent method (HJ 533-2009);
The detection principle is that ammonia nitrogen in the form of free ammonia or ammonium ions reacts with Nessler's reagent to form a reddish-brown complex whose absorbance is proportional to the content of ammonia nitrogen.
(1.) Add 1ml of water sample to be tested in the matching small test tube
(2.) Add 4 drops of matching reagents, cover and shake well
(3.) Take a test paper and immerse it in a small test tube for 10 seconds
(4.) Shake off the excess solution on the test paper and immediately compare it with the color chart.
Industry application: Because of its wide range, the Na-type method produces data quickly. It is widely used for wastewater testing in printing and dyeing factories, textile factory wastewater, environmental protection projects, sewage treatment plants and other industries.