2 replies to this topic

[aliadnan]

Hi
Is there any way to separate ammonia which is dissolved by some means during process in water? That water is the waste water. The solution should be cost effective and easy to handle. I hope to get some good responses on this.
Thanks for the help in advance.

Alidnanan...

I think the answers you seek will require a bit more information. Is the wastewater for re-use or discharge? What else is in the water... etc.

Ammonia water separation can be achieved with air stripping in a packed tower. This requires reasonably high pH for good removal... say 11, so lime or caustic may have to be added - with further post-treatment to rsmove Ca or Na (possibly performed in existing plant?) - may involve scaling issues - should be reliable

Biological treatment also widely used. Anaerobic and Aerobic digesters (or zones) are used (together) in various combinatons. Ammonia is converted to Nitrite and then Nitrate by bacteria. Other bacteria can then convert the Nitrate to N2 if conditions are correct... for example may need to provide carbon source, monitor O2, BOD etc.

Ion exchange - good for high capacities and concentrations, small area etc.

There is a fair amount of info online - the US EPA website is often good for this sort of thing and may have other options, general design guidelines/rules of thumb... etc.

Nat

[Samir Gupta]

If this stream contains free ammonia, air stripping in a packed tower may be the best solution. For better results, hot air may be used for stripping. However, this works best for removing small amount from the final discharge and acts as a polishing filter.
For a more concentrated solution (above 2%) , the waste water stream may be pre-heated above 100 degree C and then flashed in a column. The flashed portion may be condensed in an overhead condenser and the acquous ammonia may be recycled. Please note that the waste water has to be under pressure (say pump's discharge) and higher the pressure of the water the more is the possible teperature rise for the pre heating and therefore better flash recovery.
Alternatively, live steam may be injected in the system to heat the waste stream prior to flashing. The disadvantage is the addition of more water into your waste stream.
In case the stream contains bounded ammonia and is not 'free' ammonia, the best way would be to neutrilize it with a waste acid stream from your process.
Hope this helps...
Samir