TY - JOUR
T1 - Recovering chemical sludge from the zero liquid discharge system of flue gas desulfurization wastewater as flame retardants by a stepwise precipitation process
AU - Guo, Jiaming
AU - Zhou, Zhen
AU - Ming, Qiang
AU - Sun, Dongqi
AU - Li, Fei
AU - Xi, Jiafu
AU - Wu, Qiong
AU - Yang, Jian
AU - Xia, Qing
AU - Zhao, Xiaodan
N1 - Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/9/5
Y1 - 2021/9/5
N2 - In this study, a five-stage stepwise precipitation process, including pre-sedimentation, magnesium removal, gypsum precipitation, ettringite precipitation and calcium removal, was proposed as a softening pretreatment for zero liquid discharge system for flue gas desulfurization wastewater. Batch tests and long-term bench-scale experiment showed that magnesium, sulfate and calcium were efficiently removed with efficiencies all above 98.0%, leaving a clean effluent majorly containing NaCl and NaOH. The precipitated CaSO4, CaCO3, Mg(OH)2 and ettringite were completely separated by stepwise precipitation, and the purity of Mg(OH)2 and ettringite were further enhanced by washing and soaking treatment. CaSO4 and CaCO3 can be directly recycled as gypsum product and desulfurizing agent within the power plant, while Mg(OH)2 and ettringite presented proper particle size and excellent thermal properties as a synergistic flame retardant. The flame retardancy of ethylene vinyl acetate copolymer were greatly improved when blended with recovered Mg(OH)2 and ettringite, and possessed better performance by blending them together because ettringite could act as a dispersing and compatible agent of Mg(OH)2, and relieve the intensity of smoke releasing. Chemical sludge recovery compensates the total cost of the five-stage process by 45.0%, and makes the process technically versatile, economically beneficial and environmentally friendly without solid waste production.
AB - In this study, a five-stage stepwise precipitation process, including pre-sedimentation, magnesium removal, gypsum precipitation, ettringite precipitation and calcium removal, was proposed as a softening pretreatment for zero liquid discharge system for flue gas desulfurization wastewater. Batch tests and long-term bench-scale experiment showed that magnesium, sulfate and calcium were efficiently removed with efficiencies all above 98.0%, leaving a clean effluent majorly containing NaCl and NaOH. The precipitated CaSO4, CaCO3, Mg(OH)2 and ettringite were completely separated by stepwise precipitation, and the purity of Mg(OH)2 and ettringite were further enhanced by washing and soaking treatment. CaSO4 and CaCO3 can be directly recycled as gypsum product and desulfurizing agent within the power plant, while Mg(OH)2 and ettringite presented proper particle size and excellent thermal properties as a synergistic flame retardant. The flame retardancy of ethylene vinyl acetate copolymer were greatly improved when blended with recovered Mg(OH)2 and ettringite, and possessed better performance by blending them together because ettringite could act as a dispersing and compatible agent of Mg(OH)2, and relieve the intensity of smoke releasing. Chemical sludge recovery compensates the total cost of the five-stage process by 45.0%, and makes the process technically versatile, economically beneficial and environmentally friendly without solid waste production.
KW - Chemical precipitation
KW - Flame retardant
KW - Limiting oxygen index
KW - Sludge
KW - Zero liquid discharge
UR - https://www.scopus.com/pages/publications/85105579178
U2 - 10.1016/j.jhazmat.2021.126054
DO - 10.1016/j.jhazmat.2021.126054
M3 - 文章
C2 - 33992018
AN - SCOPUS:85105579178
SN - 0304-3894
VL - 417
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
M1 - 126054
ER -
