Influences of different iron forms activated peroxydisulfate on volatile fatty acids production during waste activated sludge anaerobic fermentation

Jingyang Luo; Wenxuan Huang; Ying Zhu; Wen Guo; Li Yibing; Lijuan Wu; Qin Zhang; Yang Wu; Fang Fang; Jiashun Cao

doi:10.1016/j.scitotenv.2019.135878

Influences of different iron forms activated peroxydisulfate on volatile fatty acids production during waste activated sludge anaerobic fermentation

Sci Total Environ. 2020 Feb 25:705:135878. doi: 10.1016/j.scitotenv.2019.135878. Epub 2019 Nov 30.

Authors

Jingyang Luo¹, Wenxuan Huang², Ying Zhu², Wen Guo², Li Yibing², Lijuan Wu³, Qin Zhang², Yang Wu², Fang Fang², Jiashun Cao²

Affiliations

¹ Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China. Electronic address: luojy2016@hhu.edu.cn.
² Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China.
³ Jiangsu Provincial Key Laboratory of Environmental Engineering, Jiangsu Provincial Academy of Environmental Science, Nanjing 210036, China.

PMID: 31972926
DOI: 10.1016/j.scitotenv.2019.135878

Abstract

The treatments of peroxydisulfate (PDS) activated with different iron forms (zero-valent iron (ZVI), ferrous iron (Fe²⁺) and nano zero-valent iron (NZVI)) all contributed to the generation of volatile fatty acids (VFAs) during waste activated sludge (WAS) anaerobic fermentation. The maximal VFAs generation was 3036, 5537 and 3533 mg COD/L in the PDS/ZVI, PDS/Fe²⁺ and PDS/NZVI reactors, respectively, while it was only 702 mg COD/L in the control. The enhancing effects followed the order of PDS/Fe²⁺ > PDS/NZVI > PDS/ZVI. ZVI and NZVI showed no dual promoting effects with PDS on the VFAs production. Mechanisms exploration indicated that the simultaneous improvement of WAS solubilization and hydrolysis (high concentrations of soluble proteins and carbohydrates) and enrichment of fermentative bacteria (i.e. Bacteroides, Clostridium, Fonticella, and etc.) involved in VFAs generation were the main causes of VFAs promotion in the PDS treated systems. However, the reductive ZVI and NZVI partially consumed the generated free radicals (i.e. SO₄^- and/or OH), which possess strong oxidative potentials and are the main contributors to extracellular polymeric substances disintegration in WAS. This consumption of free radicals accounted for the lower efficiency of solubilization and hydrolysis and consequently reduced VFAs production in the PDS/NZVI and PDS/ZVI reactors compared with that in PDS/Fe²⁺ reactor. Moreover, the treatment of PDS activated by different forms of iron improved the VSS reduction extent and dewaterability of fermented sludge compared with that of the control, which is advantageous to the ultimate disposal of WAS.

Keywords: Anaerobic fermentation; Dewaterability; Iron forms; Peroxydisulfate (PDS); Volatile fatty acids (VFAs); Waste activated sludge (WAS).

MeSH terms

Anaerobiosis
Fatty Acids, Volatile
Fermentation
Iron
Sewage*

Substances

Fatty Acids, Volatile
Sewage
Iron