Effects of sludge-reflux ratio and energy substrate dose on sludge bioleaching with a two-phase baffled flow reactor

作者：Pan, Jiajing; Dai, Yu; Liu, Hongtao; Wu, Rongjun; Zhang, Jun^*; Lu, Yulan

来源：Desalination and Water Treatment, 2022, 278: 82-92.

DOI：10.5004/dwt.2022.29089

• Sewage sludge
• Bioleaching
• Dewaterability
• Heavy metal
• Sludge-reflux ratio
• Energy substrate dose

Although two-phase bioleaching can enhance the dual effects of sludge dewaterability improve-ment and heavy-metal removal due to a superior microbial synergistic effect caused by phase sep-aration, it has not been widely applied because of the unclear optimal ranges of several essential parameters, such as sludge-reflux ratio and energy substrate dose. Therefore, we investigated how the sludge-reflux ratio (15%/10%, 25%/0%, 40%/0%, for the 1st/2nd compartment) and energy-sub-strate dose (FeSO4 center dot 7H2O: 2, 6, and 10 g/L) affected the two-phase bioleaching process of sewage sludge with a baffled flow bioreactor in this study. The results showed that increasing sludge reflux resulted in rapider acidification but no significant increase in bioleached sludge dewater-ability, whereas increasing sludge reflux in 1st compartment enhanced the removal rates of Cu, As, and Pb but had no remarkable effects on Cd, Zn, Ni, and Cr. The acidification and removal rates of heavy metals increased when the FeSO4 center dot 7H2O dose was increased from 2 to 10 g/L, whereas sludge dewaterability only increased from 2 to 6 g/L. Under optimal conditions (25% sludge-re-flux ratio and 6 g/L FeSO4 center dot 7H2O), the specific resistance to filtration and capillary suction time of the sludge decreased by 96.14% and 75.88% after bioleaching, respectively, and the corresponding removal rates of heavy metals were 65.35% (Cd), 65.05% (Zn), 44.31% (Cu), 23.88% (As), 15.81% (Ni), 11.31% (Cr), and 8.15% (Pb).

• 单位
  中国科学院; 桂林理工大学