Hi all,
I'm working on municipal wastewater treatment and am using MAP precipitation technique for nutrients recovery.
I found out from other literature that this method is commonly used in some especial industrial wastewater that contains a lot of ammonium (usually around 1000 mg/L), and although the removal efficiency is at least more than 90%, after that it still has a significant amount of ammonium.
As I need to achieve acceptable nutrient limits (
Hi Marzieh
My suggestion will be to look for removal of ammonia by either air stripping or ion-exchange adsorption methods for low-strength ammoniacal-nitrogen wastewater.
It is necessary to add magnesium and phosphate in proper ratio to get ammonium precipitated as MAP. Another problem would be conversion of organic nitrogen to ammonia by nitification/denitrification process. Even after additional inputs the amount of MAP recovered would be very low.
Hence, the better option would be to remove ammonium rather than its recovery.
Best luck!
Regards
Sumathi M
Remember that MAP is a chemical reaction which requires a driving force to form the precipitate. That driving force is a function of the pH ( >7.5) and the concentration of Mg, NH3, and PO4. If this is municipal WW and I see you have about 50 mg/L of NH3 - then I'm guessing you probably have about 10 mg/L of TP with generally 60% as PO4-P or 6 mg/L. Regardless of the NH3 concentration - which already is too low to practically generate MAP, the PO4 is way too low as well. Thus to create MAP, you'd have to add chemicals to (a) increase the pH; (b) add Mg; and also (c) add PO4-P. And you'll have to add a lot of P. It would likely be far more cost effective to do biological treatment.
Marzieh Niksefat The answer about using MAP in this case is definitely NO in terms of technical feasibility, environmental performance and economics (high capital and operating costs). I agree with Peter Balslev
that biological N-removal would be most efficient and sustainable especially when using the nitrite (NO2-) shortcut with 50% nitritation and anammox to convert the ammonia (NH4+) to inert nitrogen gas (N2) with low energy consumption and without adding any chemicals ( alkalinity and organic carbon).Also air stripping will not work at such low ammonia levels and neutral pH.
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