Assessing activated sludge morphology and oxygen transfer performance using image analysis

Area of Science:

• Environmental microbiology
• Wastewater treatment engineering

Background:

• Microbial community morphology influences activated sludge process performance.
• Key morphological parameters require accurate quantification for process optimization.

Purpose of the Study:

• To develop and calibrate an image analysis technique for quantifying microbial morphology in activated sludge.
• To investigate the impact of specific filament length (SFL) on process performance and energy use.

Main Methods:

• Development and calibration of an image analysis technique.
• Measurement of morphological parameters including floc diameter and SFL.
• Correlation analysis between SFL and performance indicators.

Main Results:

• SFL significantly impacts sludge floc size, extracellular polymeric substances production, settleability, mixed liquor viscosity, and oxygen transfer efficiency.
• Increased SFL led to a 67% rise in normalized apparent viscosity and a 29% decrease in oxygen transfer efficiency.
• Long solids retention time (SRT) reduced SFL, enhancing sludge settling and oxygen transfer.

Conclusions:

• Microbial morphology, particularly SFL, is a critical factor in activated sludge treatment and energy performance.
• Image analysis provides a valuable tool for assessing microbial morphology.
• Optimizing SRT can mitigate negative impacts of high SFL on process efficiency.