Stability of aerobic granular sludge for simultaneous nitrogen and Pb(II) removal from inorganic wastewater

ABSTRACT

In this paper, we proposed a strategy for the establishment of an aerobic granular sludge (AGS) system for simultaneous nitrogen and Pb(II) removal from inorganic wastewater. AGS was stored in lead nitrate solution to select functional bacteria resistant to lead poison, and then an AGS system for ammonia nitrogen (180-270 mg/L) and Pb(II) (15-30 mg/L) removal was established based on carbon dosing and a two-stage oxic/anoxic operational mode. After storage for 40 days, the stability of AGS decreased because specific oxygen uptake rate, nitrification rate and abundance of Nitrosomonas decreased to different degrees compared with those before storage. During the first 70 days of the recovery process, AGS in R₁ (the blank reactor) and R₂ (the control reactor) both experienced a first breakage and then regranulation process. The main properties of AGS in reactors R₁ and R₂ tended to be stable after days 106 and 117, respectively, but the structure of steady-state AGS in R₂ was more compact. The total inorganic nitrogen (TIN) in effluent from R₁ and R₂ basically remained below 25 mg/L after days 98 and 90, respectively. The Pb(II) concentration in effluent from R₂ was always below 0.3 mg/L. On day 140, the relative abundance of Nitrosomonas in R₂ (6.17%) was significantly lower than that in R₁ (12.15%), whereas the relative abundance of denitrifying bacteria was significantly higher than that in R₁ (62.44% and 46.79%). The system removed 1 kg of influent TIN only consuming approximately 1.85 kg of carbon source, demonstrating clear advantages in energy savings.

GRAPHICAL ABSTRACT

KEYWORDS:

• Aerobic granular sludge
• pb(II)
• nitrification
• denitrification
• stability

Acknowledgement

This research was supported by National Natural Science Foundation of China (No. 52060007), Science and Technology program of Education Department of Jiangxi Province (GJJ190502), The Program of Qingjiang Excellent Young Talents, Jiangxi University of Science and Technology (JXUSTQJYX2020008), and the Opening Project of Henan Province Key Laboratory of Water Pollution Control and Rehabilitation Technology (CJSP2021004).

Disclosure statement

No potential conflict of interest was reported by the authors.

Data Availability Statement

The authors confirm that the data supporting the findings of this study are available within the article and its supplementary materials.

Additional information

Funding

This work was supported by Education Department of Jiangxi Province: [Grant Number GJJ190502]; Jiangxi University of Science and Technology: [Grant Number JXUSTQJYX2020008]; National Natural Science Foundation of China: [Grant Number 52060007]; Henan Province Key Laboratory of Water Pollution Control and Rehabilitation Technology: [Grant Number CJSP2021004].