The Synthesis of Secondary Iron Minerals Induced by Quartz Sand during the Bioleaching Process Improves the Dewaterability of Municipal Sewage Sludge

Minerals

Yongwei Song¹  Yiqian Wu¹  Zehao Guo¹  Heru Wang¹  Yingying Ma¹ 

[1] Department of Environmental Science and Engineering, Zhongnan University of Economics and Law, Wuhan 430073, China;

关键词: Acidithiobacillus ferrooxidans;    quartz sand;    municipal sewage sludge;    secondary iron minerals;    dewaterability;   

DOI  :  10.3390/min8100419

来源: DOAJ

【 摘 要 】

This study elucidated the mechanisms during the bioleaching process when optimizing the dewaterability of municipal sludge using quartz sand. The experiment was conducted with a shaking table and a series of controlled trials designed to investigate the influence of quartz sand on sludge dewaterability. Scanning electron microscopy and X-ray diffraction were applied to explore the quartz sand’s action mechanism. Results indicated that quartz sand could improve the sludge bioleaching efficiency. The optimal reaction time was between 24–48 h and 48–72 h with and without 10 g·L−1 of quartz sand, and a minimum sludge specific resistance to filtration was 1.2 × 1012 and 2.4 × 1012 m·kg−1, respectively. Quartz sand could provide nucleating sites for secondary iron minerals and overcome the unfavorable influence of a low Fe3+ supply rate in the initial bioleaching stage (0–24 h). Because it was conducive to accelerating the initial mineral precipitation, quartz sand could improve bioleaching efficiency. The X-ray diffraction spectrum showed that quartz sand induced changes in the synthesis pathway of secondary iron minerals when the concentration of Fe2+ ≥ 4 g·L−1. This then promoted the transformation of schwertmannite into jarosite during the mineralization process, which immobilizes nutrients such as K+ and NH4+ in the form of jarosite. Accordingly, bioleached sludge dewaterability and its utilization value can be improved. These results provide theoretical reference for improving bioleaching techniques in the treatment of municipal sludge.

【 授权许可】

Unknown