Novel CaO2 beads used in the anaerobic fermentation of iron-rich sludge for simultaneous short-chain fatty acids and phosphorus recovery under ambient conditions

Qian Ping; Zhipeng Zhang; Xiaohu Dai; Yongmei Li

doi:10.1016/j.biortech.2020.124553

Novel CaO₂ beads used in the anaerobic fermentation of iron-rich sludge for simultaneous short-chain fatty acids and phosphorus recovery under ambient conditions

Bioresour Technol. 2021 Feb:322:124553. doi: 10.1016/j.biortech.2020.124553. Epub 2020 Dec 17.

Authors

Qian Ping¹, Zhipeng Zhang¹, Xiaohu Dai², Yongmei Li³

Affiliations

¹ State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
² State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
³ State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China. Electronic address: liyongmei@tongji.edu.cn.

PMID: 33359566
DOI: 10.1016/j.biortech.2020.124553

Abstract

A novel composite CaO₂ bead was prepared to improve total short-chain fatty acids (TSCFAs) production and phosphorus (P) recovery from iron-rich waste activated sludge (WAS) during ambient anaerobic fermentation. Results showed that CaO₂ mass percentage of 5% and CaCl₂:nylon66 = 1:1 (mass ratio) were the optimal prescription for the preparation of CaO₂ beads with porous structure, loose morphology, and sustained-release of CaO₂. The highest TSCFAs production (356 mg/g VSS) was observed and about 9% of P in sludge could be recovered on beads. The decrease of Fe-phosphate and Fe-oxides in the sludge were due to different mechanisms. Microbial community analyses showed that CaO₂ beads effectively enriched dissimilatory iron-reducing bacteria (DIRB) and promoted iron-reduction related genes. After fermentation, the P-rich beads are easy to separate from sludge for further P recovery, and the supernatant carrying abundant acetate and Fe²⁺ can be returned to the wastewater treatment line to improve nutrient removal.

Keywords: Ambient anaerobic fermentation; Calcium peroxide; Dissimilatory iron-reducing bacteria; Iron-rich sludge; Short-chain fatty acids.

MeSH terms

Anaerobiosis
Fatty Acids, Volatile
Fermentation
Iron
Phosphorus*
Sewage*

Substances

Fatty Acids, Volatile
Sewage
Phosphorus
Iron