Zero liquid discharge(ZLD) of wastewater generated by flue gas desulfurization(FGD) system of coal-fired power plants is a hot and difficult issue in the industry. A ZLD process of FGD wastewater integrated with pre-treatment

intensive softening

pre-concentration and evaporation-crystallization units was established

through quality analysis for desulfurization waste water. Moreover

a 25 m~3/d pilot-scale test was carried out. The results show that

all units of the process operated efficiently and stably

and realized ZLD. The pretreatment module consisting of primary sedimentation tank and sequencing batch softening reactor realized simultaneous removal of suspended substance(SS)

hardness

organic matter and heavy metals by adding lime

sodium hydroxide(Na OH)

sodium carbonate(Na_2CO_3) and flocculants. The removal efficiency of SS

Ca~(2+)

Mg~(2+) and organic compounds reached 97.3%

38.1%

98.5% and 74.3%

respectively. The intensive softening unit

including filter

ultrafiltration(microfiltration) and nanofiltration unit

could efficiently intercept divalent ions and organic compounds. The concentrations of Ca~(2+)

Mg~(2+) and sulfate in the effluent of nanofiltration unit were 5.2

0.4 and 84.3 mg/L

respectively

which reduced the risk of membrane fouling and guaranteed quality of industry salt product. After electrodialysis

ion exchange and evaporation crystallization

the purity of the obtained industrial salt met the requirements of the secondary industrial wet salt in the National Standard for Industrial Salt(GB 5462—2015).