Study on decaying characteristics of activated sludge from a circular plug-flow reactor using response surface...

Area of Science:

• Environmental Science
• Microbiology
• Biotechnology

Background:

• Activated sludge is crucial for wastewater treatment.
• Understanding factors affecting sludge decay is vital for process optimization.
• Previous studies have explored various decay factors with varying methodologies.

Purpose of the Study:

• To investigate the decay characteristics of activated sludge.
• To determine the most significant factors influencing sludge decay: pH, temperature, and dissolved oxygen.
• To quantify the contribution of reduced cell activity versus cell death to overall sludge decay.

Main Methods:

• Utilized a laboratory-scale circular plug-flow reactor for activated sludge generation.
• Employed batch experiments with response surface methodology for experimental design.
• Combined LIVE/DEAD® Baclight technique with 2,3,5-triphenyl tetrazolium chloride - dehydrogenase activity assay.

Main Results:

• pH was identified as the most influential factor in activated sludge decay.
• Temperature and dissolved oxygen were found to be secondary influential factors.
• Sludge activity decay was attributed to 40.94-90.03% reduced cell activity, with the remainder due to cell death.

Conclusions:

• pH is the dominant factor controlling activated sludge decay.
• Wastewater treatment processes should prioritize pH control for sludge stability.
• Both reduced cellular activity and cell death contribute to sludge decay, with reduced activity being the major component.