hypochlorite oxidation of ammonia: ORP control

[kiamaster]

I am developing a program to remove NH3 from wastewater (ammonia; 500-600mg/L) by using sodium hypochlorite to oxidize ammonia. Has anyone any experience with this kind of application? A literature search shows that it can be done at pH 7 - 8 and controlled by ORP. I cannot find any ORP value to use to control the reaction. Any information will be greatly appreciated.

 

[bimr]

Most have found this this process to be impractical at ammonia nitrogen concentrations of 20 mg/l. You have 500 mg/l ammonia nitrogen

The stoichiometric amount of chlorine to ammonia is approximately 10:1. So you will be adding a large amount of chlorine.

Assuming the conncentration is constant, you can add chlorine in proportion to the flow. A chlorine residual analyser can be used to limit overfeeding of chlorine.

Have you considered alternative methods of disposal? Ammonia is commonly used as a nutrient in the activated sludge process. You may be able to dispose of this material for little cost.

http://www.rmtech.net/Aqua Ammonia.htm

 

[siretb]

Bimr: when using hypochlorites to oxidize ammonia you mention 10:1 stoechiometry.
What kind of residence time is needed and what are the by products: chloramines?
Thanks Bernard

 

[bimr]

The reaction time would probably be similiar to the oxidation time for hydrogen sulfide which is about 10 minutes.

Breakpoint chlorination would have have to be used. This means that enough chlorine would have to be added to oxidize the chloramines. There would be a small amount of chloramines present. Some choramines are resistant to ozidation.