Chemical precipitation for WWTP

Hi!

I am using WEST 2014 (SP1) and setting up a full-scale WWTP with post-precipitation (FeCl3).
I am wondering if there is an icon for chemical addition available where one can select the precipitant?
I know it is available for C-source but not for e.g. P-removal.

Somebody can either confirm or clearify?
Thank you very much in advance.

Tobias, Sweden

Yes: the same icon (chemical dosing) is attached to FeCl3 and other dosing models for P-precipitation - if the right instance is selected, i.e. either ASM2d or 3P_EAWAG. If you are using an instance, e.g. ASM1, that does not model P, those icons are not enabled in the Block Library.

Hi
ASM2d has FeCl3 precipitation (I found it - Thank you!).

However, by using ASM2d I cannot apply the Anaerobic Digester (Sludge Treatment) which I can only do if I use ASM1Temp (therefore I did not find the Iron-button).

Regards
Tobias

Correct. And that's because there are 3 anaerobic digestion models in WEST: Siegrist, Lessard-Desjardins (both explicitly written with reference to ASM1 components) and ADM1 (for which only the interface to ASM1 and ASMG1 is available).
Bottom line is: with the standard model library, one can only use an anaerobic digester within ASM1 (or -G1); or, conversely, cannot use an anaerobic digester in combination with P-precipitation.
There may be two ways around.
1) write a dedicated interface, e.g. ADM1/ASM2d (I might have something - I can contact you via email)
2) turn to the plant-wide model (PWM_SA) which incorporates all

Hi again!

I was wondering about the Fe-dosing for P-removal.

I have tried alot now but I cannot see any change in the P-removal even if I enter utopic numbers but there is not any change in the TP, S_PO concentration.

I try to control the P-removal with a PO4-sensor linked to the FeOH-tank and tell the controller that PO4 should be 0.5 after adding the FeOH.

Can you explain very briefly how to set up a good pre-precipitation with the Fe-dosing unit?

Thank you very much in advance.

Tobias

I would imagine everything depends on what kind of control model are you using "between" the PO sensor and the chemical dosing blocks.
For instance, if you take an OnOff, where the output signal "u" is linked to the flow rate of the dosing unit, you could set it up as follows:
[list]
[li]if PO < lower bound, e.g. 0.2-3 then lower or stop dosage (e.g. uOn = 0)[/li]
[li]if PO > upper bound, e.g. 0.6 then increase dosage (e.g. uOff = 50)[/li]
[/list]

Hi!

Thank you very much for your fast reply.

I have tried as you recommended and tried other controllers and "overdosed" Fe into the stream but neither me nor my colleague (he works with post-precipitation) can get a precipitation.
Do we need a "reaction chamber" or similar or does it "react" immediately.

Do you have a very simple example for us (we can download from somewhere or can you send us a project) where one can see a change in the y_PO before and after adding Fe?

Thank you very much in advance.

Tobias

No reaction chamber / mixing tank is needed: it's an inline dosage principle.
With the system depicted in the figure (will send you the project separately), I can achieve the following (average +/- st.dev (5%-ile - 95%-ile)):
[list]
[li]No dosage[/li]
[list]
[li]TP removal: 0.16 +/- 0.29[/li]
[li]PO in effluent (mg/l): [b]9.6[/b] +/- 2.1 ( 5.2-12.8 ) [/li]
[/list]
[li]FeOH dosage[/li]
[list]
[li]TP removal: 0.87 +/- 0.08[/li]
[li]PO in effluent (mg/l): [b]0.46[/b] +/- 0.35 ( 0.21-0.91 ) [/li]
[/list]
[/list]
Hope this will be of help.