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Updated: Aug 7, 2025
Extraction of Structural Extracellular Polymeric Substances from Aerobic Granular Sludge
Published on: September 26, 2016
Integrated resource recovery from aerobic granular sludge plants
Nouran T Bahgat1, Philipp Wilfert2, Leon Korving3
1Wetsus, European Centre Of Excellence for Sustainable Water Technology, Oostergoweg 7, 8911, MA, Leeuwarden, the Netherlands; Dept. Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629, HZ, Delft, the Netherlands.
This study integrates alkaline anaerobic digestion with aerobic granular sludge (AGS) wastewater treatment for resource recovery. It recovers extracellular polymeric substances (EPS), methane, phosphorus, and nitrogen, enhancing sustainability in wastewater management.
Area of Science:
- Environmental Engineering
- Biotechnology
- Resource Recovery
Background:
- Aerobic granular sludge (AGS) wastewater treatment plants generate significant sludge volumes.
- Resource recovery from wastewater sludge is crucial for sustainable water management and circular economy principles.
Purpose of the Study:
- To evaluate the combined recovery of phosphorus, nitrogen, methane, and extracellular polymeric substances (EPS) from AGS.
- To assess the feasibility of integrating alkaline anaerobic digestion (AD) for enhanced resource recovery.
Main Methods:
- Development of a laboratory protocol for EPS extraction mimicking demonstration-scale conditions.
- Establishment of mass balances for EPS extraction at laboratory, demonstration, and full scales within an AGS WWTP.
- Evaluation of resource recovery feasibility based on concentrations, loads, and existing technologies.
Main Results:
- Integration of alkaline AD recovered approximately 30% of sludge organics as EPS and 25-30% as methane (≈260 ml methane/g VS).
- Phosphorus recovery: 20% in EPS, 20-30% in acidic liquid waste, and 15% in AD centrate, all recoverable via chemical precipitation.
- Nitrogen recovery: 30% as organic nitrogen in EPS. High ammonium concentration (2600 mg NH4-N/L) in AD centrate is feasible for recovery.
Conclusions:
- Alkaline anaerobic digestion effectively enhances resource recovery from AGS, including EPS, methane, phosphorus, and nitrogen.
- The AD centrate presents a viable stream for ammonium recovery due to its high concentration.
- The study demonstrates a feasible pathway for resource recovery from wastewater sludge, contributing to sustainable wastewater treatment.
