AL CONCENTRATION EXCEEDS DRINKING WATER LIMIT AT LOW AND HIGH pH

The PHREEQC input file al_conc.phr : 


       SOLUTION 1; Al 0.2 mg/kgw; pH 4 Gibbsite
       SOLUTION 2; Al 0.2 mg/kgw; pH 10 Gibbsite

       PRINT; -reset false; -user_pr true
       USER_PRINT; -start; 10 print 'Solution ', cell_no, ':    pH =', -la("H+"); -end
       END
adapts the pH of the solution to be in equilibrium with gibbsite for the indicated concentration of 0.2 mg Al/ kg water.
Running the file gives as output: 

       ----------------------------------User print-----------------------------------

       Solution             1 :    pH =   4.4661e+00 

       ----------------------------------User print-----------------------------------

       Solution             2 :    pH =   9.4229e+00

At pH < 4.47 and pH > 9.42, the Al concentration can be expected to be higher than the drinking water limit of 0.2 mg/L.

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