Table 3 Variables and levels used in the modified OFAT screening strategy

CaSO₄ .2H₂O

0.4 g/L

2 g/L

MgCl₂ .6H₂O

2 g/L

4 g/L

Phosphate stock solution (1) (5.44 g/L KH₂PO₄ and 5.67 g/L Na₂HPO₄)

0.27 g/L of KH₂PO₄ and 0.28 g/L of Na₂HPO₄ (50 mL of phosphate stock solution (1)/L)

–

Phosphate stock solution (2) (27.22 g/L KH₂PO₄ and 28.39 g/L Na₂HPO₄)

–

1.36 g/L of KH₂PO₄ and 1.41 g/L of Na₂HPO₄ (50 mL of phosphate stock solution (2)/L)

NH₄Cl (53.49 g/L and 160.4 g/L stock solutions)

0.535 g/L (10 mL of 53.49 g/L NH₄Cl stock solution/L)

1.6 g/L (10 mL of 160.4 g/L NH₄Cl stock solution/L)