Table 1 Experimental parameters for calcium carbonate crystallization in FBHC

Q_CO3, Q_Ca (mL min ^− 1)

Influx of CO₃-containing wastewater and Ca solution, respectively

(CO₃²⁻)_in (M)

The influent concentration of CO₃

(CO₃²⁻)_t, (CO₃²⁻)_d (M)

Total and soluble of carbonate in effluent

A (cm²)

Cross-section area of reactor

V_T (mL)

The total volume of the reaction solution in the reactor

L (kg m^− 2 h^− 1)

Cross-section loading

\(\frac{{{\text{C}}_{\text{CO3 }}\text{Q}}_{\text{CO3 }}\text{ }}{\text{A}}\)

Q_T (mL min ^− 1)

Total influx flow rate

Q_CO3 + Q_Ca

HRT (min)

Hydraulic retention time

\(\frac{{V}_{T }}{{ Q}_{T }}\)