Global insights into extracellular polymeric substances from activated sludge: Yield, composition, and microbial...

Area of Science:

• Environmental Microbiology
• Biotechnology
• Wastewater Engineering

Background:

• Activated sludge (AS) wastewater treatment produces significant excess sludge, increasing operational costs.
• Extracellular polymeric substances (EPS) in AS are a potential resource for recovery, reducing sludge volume and adding value.
• Understanding EPS composition and its link to microbial communities is crucial for effective recovery.

Purpose of the Study:

• To characterize alkaline-extractable EPS yields and composition from global AS plants.
• To investigate correlations between EPS yield, microbial community structure, and operational parameters.
• To evaluate Fourier Transform Infrared (FTIR) spectroscopy as a high-throughput EPS characterization tool.

Main Methods:

• Analysis of extracted EPS from 16 wastewater treatment plants across 5 continents.
• Quantification of EPS yield (wt.% VSS).
• Microbial community profiling and Fourier Transform Infrared (FTIR) spectroscopy for compositional analysis.

Main Results:

• Alkaline extractable EPS yields varied widely (2.81-18.5 wt.% VSS) globally.
• Microbial community composition did not correlate with EPS yield.
• Sludge retention time showed a significant positive correlation with EPS yield (p < 0.005).
• FTIR effectively distinguished EPS composition, with biological phosphorus removal systems showing higher lipid/polysaccharide content and chemical systems higher protein content.

Conclusions:

• Wastewater treatment design and operation influence EPS functional groups extracted via the alkaline method.
• FTIR is a valuable high-throughput tool for characterizing EPS composition.
• Further research is needed to link extracted EPS composition with microbial community structure for optimized resource recovery from wastewater sludge.