Generic PHREEQC Database

[celine1]

Dear all,

I am using PHREEQC for modelling of wastewater treatment plants.
However, I discovered that some important species/components/reactions occuring in treatment plants are not included in the PHREEQC database, such as AlPO4 precipitation, K-struvite precipitation, as well as multiple species that are included in MINTEQ but not in PHREEQC. I think it might be interesting to extend the database for application to wastewater treatment and nutrient recovery systems.

Moreover, when coupling a PHREEQC code to the Tornado/West engine for speciation calculation, I have an issue with the units. In the PHREEQC code the units of the initial solution are expressed as mol/m3. However, in the selected output file, the units always appear in kmol/m3. Even when I explicitely mention in the code that the inputs should also be read as kmol/m3. Is there an explanation for this issue ?

Thanks,
Céline

[dlparkhurst]

There are multiple databases for PHREEQC, including two derived from MINTEQ (minteq.dat and minteq.v4.dat), which are distributed with all versions of PHREEQC. I did not see struvite or AlPO4 listed in them, but there is an AlPO4 phase in llnl.dat. It is certainly possible to extend any of these databases with additional aqueous species and phases by using SOLUTION_MASTER_SPECIES, SOLUTION_SPECIES, and PHASES data blocks.

Units of input in SOLUTION are mmol/kgw by default. You can use -units to set umol/L, mmol/L, or mol/L (as well as other units of mass ug/L, mg/L, or g/L). You can also set individual element concentrations to different units from the default. However, units for all elements must be consistently /L, /kgw, or /kgs.

Most output for SELECTED_OUTPUT is in moles or moles per kg water. However, with USER_PUNCH, additional data can be added to the selected output file. You can use USER_PUNCH to convert to other units.

USER_PUNCH
-head PO4_mg/kgw
10 PUNCH TOT("P") * GFW("PO4") * 1000