I would imagine it should be installed at the end of the aeration tank. You can then use this meter to help determine the minimum dose of chemical (aluminum or iron salt) needed to precipitate any remaining phoshphorus. If you wanted to be extremely efficent you could control your chemical feed pump off the phoshate analyzer too.

I'm not familiar with this particular meter, but it's always important to keep up on their maintenance needs, keep them properly calibrated, and still do in house testing to confirm that they're working.

Hach should help provide you with assistance too if needed.

best regards,

Ryan

Mr. Roger w/ Hach

This a phosphate analyzer (0-50 mg/L range),HACH make.

We have installed it in the aeration tank inlet. I need to now if it is the right location. Also, how the phosphates are analyzed from the mixed liquor

Hello VC,

Sounds like the Phosphax, which uses the Molybdovanadate method where PO4 reacts with the molybdate to form a complex that then reacts with vanadium in the reagent.  The yellow color formed by the complex is proportional to the PO4 level.  This link will take you to our bench methods, which have more explanation if you need it.
http://www.hach.com/quick.search-download.search.jsa?keywords=molybdovanadate  One key thing, the reaction only occurs with "free" PO4 and this is not a "total" PO4 analyzer.

As far as location of the sampling point, can't speak to your situation as I don't know the goal of your facility when it comes to PO4.  Nor, what type of PO4 control you are using.  I always want to know "why are you testing for (name of analyte, in your case PO4) at this point, and does this data help you with your process downstream of this point?"  I'll leave it up to you to help me (and others, except Dallas) figure out if the location you have is proper for what your goals are should you want to dig deeper via the forum.

If you are in the USA our Process Tech Help team is avail 6:30-5 Mtn time (800-227-4224 x6132).  I can also steer you towards your US field rep, or connect you with your international connection.  Drop me a message.  

Hello VC,

Measuring PO₄-P at the inlet to the oxic zone would give you an idea of maximum P release.  However, I believe you are better suited having the analyzer at the end of the oxic zone to provide an early warning of a potential upset.

Cheers, RS