Shear-driven stirring optimization modulates microbial synergy for robust structural-metabolic performance in...

Area of Science:

• Environmental Microbiology
• Biotechnology
• Wastewater Treatment

Background:

• Microalgal-bacterial granular sludge (MBGS) is a promising technology for wastewater treatment.
• Optimizing operational parameters is crucial for enhancing MBGS efficiency and stability.
• Stirring speed is a key factor influencing the physical and biological properties of granular sludge.

Purpose of the Study:

• To systematically investigate the impact of stirring speed on MBGS performance.
• To identify the optimal stirring speed for treating simple organics.
• To elucidate the structural and metabolic adaptations induced by stirring.

Main Methods:

• MBGS were operated at various stirring speeds (0–250 rpm).
• Granule morphology, homogeneity, and stability were analyzed.
• Microbial community structure and functional gene abundance were assessed using molecular techniques.

Main Results:

• An optimal stirring speed of 210 rpm was identified, significantly improving granule morphology, homogeneity, and stability.
• This speed promoted an optimal microalgae-bacteria ratio and increased the abundance of specific bacterial taxa (Pseudomonadota).
• Key functional genes involved in contaminant metabolism were upregulated at 210 rpm.

Conclusions:

• Stirring shear force is a critical factor for maintaining MBGS granule size and stability.
• Optimized stirring speed can induce synergistic structural and metabolic adaptations for efficient organic contaminant removal.
• This study provides strategic insights for the real-world application of MBGS technology.