Migration and distribution of sodium ions and organic matters during electro-dewatering of waste activated sludge at different dosages of sodium sulfate

TY - JOUR

T1 - Migration and distribution of sodium ions and organic matters during electro-dewatering of waste activated sludge at different dosages of sodium sulfate

AU - Xiao, Jun

AU - Wu, Xu

AU - Yu, Wenbo

AU - Liang, Sha

AU - Yu, Jiangwei

AU - Gu, Yueyuan

AU - Deng, Huali

AU - Hu, Jiukun

AU - Xiao, Keke

AU - Yang, Jiakuan

N1 - Publisher Copyright: © 2017 Elsevier Ltd

PY - 2017

Y1 - 2017

N2 - In this study, the influence of Na2SO4 on electro-dewatering (EDW) of waste activated sludge (WAS) was investigated. The highest water removal efficiency of 42.5% was achieved at the optimum Na2SO4 dosage of 12.5 g kg−1 DS during EDW process at a constant voltage of 20 V. The migration and distribution of water, organic matters and Na+ at different Na2SO4 dosages were investigated through layered experiments. The results indicated the entire EDW process followed the S curve model, and it can be divided into three stages: (1) initial desalination stage: at the initial few min of EDW process, the rate of electroosmosis was extremely slow while electromigration of ions like Na+ was intense, and the electromigration was more obvious with increased Na2SO4 dosage; (2) dewatering stage: the dewatering efficiency increased dramatically via electroosmosis; (3) the dewaterability limit stage: the maximum value of dewatering efficiency has been achieved, while the water removal efficiency and dry solids content remained constant. During the EDW process, the possible electrolysis resulted in a pH gradient in the sludge cake. With the addition of Na2SO4 in the EDW, the pH gradient was intensified, and the migration rate of organic matters moving from cathode to anode increased while compared with the raw WAS. This study provided insights into the mechanism of EDW process at different dosages of Na2SO4.

AB - In this study, the influence of Na2SO4 on electro-dewatering (EDW) of waste activated sludge (WAS) was investigated. The highest water removal efficiency of 42.5% was achieved at the optimum Na2SO4 dosage of 12.5 g kg−1 DS during EDW process at a constant voltage of 20 V. The migration and distribution of water, organic matters and Na+ at different Na2SO4 dosages were investigated through layered experiments. The results indicated the entire EDW process followed the S curve model, and it can be divided into three stages: (1) initial desalination stage: at the initial few min of EDW process, the rate of electroosmosis was extremely slow while electromigration of ions like Na+ was intense, and the electromigration was more obvious with increased Na2SO4 dosage; (2) dewatering stage: the dewatering efficiency increased dramatically via electroosmosis; (3) the dewaterability limit stage: the maximum value of dewatering efficiency has been achieved, while the water removal efficiency and dry solids content remained constant. During the EDW process, the possible electrolysis resulted in a pH gradient in the sludge cake. With the addition of Na2SO4 in the EDW, the pH gradient was intensified, and the migration rate of organic matters moving from cathode to anode increased while compared with the raw WAS. This study provided insights into the mechanism of EDW process at different dosages of Na2SO4.

KW - Desalination

KW - Electro-dewatering

KW - Migration

KW - Organic matters

KW - Waste activated sludge

UR - http://www.scopus.com/inward/record.url?scp=85029496576&partnerID=8YFLogxK

U2 - 10.1016/j.chemosphere.2017.09.034

DO - 10.1016/j.chemosphere.2017.09.034

M3 - 文章

C2 - 28926790

AN - SCOPUS:85029496576

SN - 0045-6535

VL - 189

SP - 67

EP - 75

JO - Chemosphere

JF - Chemosphere

ER -