Structure-function dynamics and modeling analysis of the micro-environment of activated sludge floc

Area of Science:

• Environmental microbiology
• Biochemical engineering

Background:

• Activated sludge flocs exhibit complex microenvironments influenced by biodegradation and mass transfer.
• Heterogeneity within flocs can lead to stratification of microbial processes, affecting overall treatment efficiency.

Purpose of the Study:

• To develop and validate an integrated model simulating the activated sludge floc microenvironment.
• To dynamically simulate combined chemical oxygen demand (COD) and nitrogen removal processes.
• To analyze the impact of varying substrate and oxygen concentrations on floc microenvironments.

Main Methods:

• Development of an integrated model for activated sludge floc microenvironment simulation.
• Dynamic simulation of COD and nitrogen removal processes.
• Experimental analysis of floc microenvironments under different wastewater strengths and oxygen levels.

Main Results:

• Model simulations and experimental data revealed heterogeneous, gradient-governed microenvironments within activated sludge flocs.
• High pollutant loads resulted in limited oxygen penetration (0.15 mm) and substrate accumulation zones.
• Lower pollutant concentrations led to fully aerobic conditions throughout the floc, with no substrate accumulation zones.

Conclusions:

• Microbial structure and function within activated sludge flocs are significantly influenced by bulk substrate and dissolved oxygen concentrations.
• The developed model provides insights into the complex dynamics of floc microenvironments and their role in wastewater treatment.
• Understanding these microenvironmental factors is crucial for optimizing activated sludge processes for COD and nitrogen removal.