Bacterial polymer production using pre-treated sludge as raw material and its flocculation and dewatering potential

Area of Science:

• Environmental Science
• Biotechnology
• Chemical Engineering

Background:

• Wastewater sludge is a significant waste product requiring effective management.
• Extracellular polymeric substances (EPS) show potential as natural flocculants and dewatering agents.
• Developing sustainable methods for EPS production is crucial for resource recovery.

Purpose of the Study:

• To investigate the production of extracellular polymeric substances (EPS) from pre-treated wastewater sludge.
• To evaluate the effectiveness of different sludge pre-treatment methods on EPS yield.
• To assess the performance of produced EPS as conditioning agents in water treatment.

Main Methods:

• Wastewater sludge was subjected to sterilization, alkaline-thermal, and acid-thermal treatments at various solids concentrations.
• Pre-treated sludge was used as a substrate for Serratia sp. fermentation to produce EPS.
• Extracted EPS (broth, capsular, slime) were tested for flocculation activity and dewatering enhancement with kaolin suspensions.

Main Results:

• Alkaline-thermal pre-treatment yielded higher EPS concentrations (3.4 g/L) compared to acid-thermal (1.5 g/L) and sterilization.
• Optimal EPS production was observed at lower sludge solids concentrations (17.0-29.8 g/L).
• EPS demonstrated significant performance, achieving 79.1% flocculation activity and 52.2% dewatering enhancement.

Conclusions:

• Wastewater sludge can serve as a viable raw material for producing high-performance EPS.
• Alkaline-thermal pre-treatment is an effective method for maximizing EPS yield.
• The produced EPS show promise as efficient conditioning agents for water and wastewater treatment applications.