DATABASE C:\Program Files (x86)\USGS\Phreeqc Interactive 3.6.2-15100\database\wateq4f.dat PHREEQC Calculations #solubility products of all relevant Mg-containing phases PHASES Newberyite MgHPO4:3H2O = 3H2O + HPO4-2 + Mg+2 log_k -5.8 #from Metha and Batstone 2013 Bobbierite Mg3(PO4)2:8H2O = 8H2O + 3Mg+2 + 2PO4-3 log_k -25.2 #from Metha and Batstone 2013 Trimagnesium Mg3(PO4)2:22H2O = 22H2O + 3Mg+2 + 2PO4-3 log_k -23.1 #from Metha and Batstone 2013 Brucite Mg(OH)2 = Mg+2 + 2OH- log_k -11.16 Struvite MgNH4PO4:6H2O = 6H2O + Mg+2 + NH4+ + PO4-3 log_k -13.36 #from Bhuiyan et al. 2007 # defining the 0.1 M (NH4)2HPO4 (DAP) solution SOLUTION 1 temp 20 pH 7 charge pe 4 redox pe units mmol/kgw density 1 N(-3) 200 P 100 -water 0.1 # kg SAVE solution 1 END # defining the 0.1 M MgCl2 solution SOLUTION 2 temp 20 pH 7 charge pe 4 redox pe units mmol/kgw density 1 Mg 100 Cl 200 -water 0.1 # kg SAVE solution 2 # allow equilibrium of the aqueous solution with forming struvite EQUILIBRIUM PHASES Struvite 0.0 0.0 # mix DAP and MgCl2 solution MIX 2 1 1 2 1