Fig. 1.
Ca2+ leaching under NH4+ shocking at different pH. (a) Different improved folds of Ca2+ dissolution vs. control group at 0 mg/L NH4+ and pH 7.0. (b) Ca2+ leaching under wash and aeration operation and different equivalent concentrations of monovalent cations. The red dashed line and two-way arrow indicated the dissolved Ca2+ concentration at 20 h in the group with NH4+ addition. (c) Average NH4+ concentration in supernatant of each group. (d) Relationships and linear fit between dissolved NH4+ concentration and dissolved Ca2+ concentration.