Recovery of Extracellular Polymeric Substances from Excess Sludge Using High-Flux Electrospun Nanofiber Membranes

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Extracellular polymeric substances (EPSs) recycling from wastewater sludge is crucial for resource recovery.
• Conventional membrane separation for EPS recovery suffers from low water flux and high energy demands.

Purpose of the Study:

• To develop and evaluate electrospun nanofiber membranes (ENMs) for efficient concentration and recycling of EPSs.
• To assess the performance of ENMs in terms of water flux, EPS recovery, mechanical strength, antifouling properties, and reusability.

Main Methods:

• Fabrication of polyvinylidene fluoride (PVDF) electrospun nanofiber membranes (ENMs).
• Extraction of EPSs from excess sludge using the cation exchange resin (CER) method.
• Dead-end filtration experiments using ENMs to recover EPSs and remove heavy metals.

Main Results:

• The fabricated ENM (14 wt.% PVDF) demonstrated high average water flux (376.8 L/(m²·h)) and EPS recovery rate (94.1%) at 20 kPa.
• ENMs exhibited excellent mechanical strength, antifouling properties, and reusability over five cycles.
• The filtration process effectively removed heavy-metal ions (Pb2+, Cu2+, Cr6+) with removal rates ranging from 73.5% to 89.5%.

Conclusions:

• Electrospun nanofiber membranes offer a promising solution for efficient EPS concentration and recycling from wastewater sludge.
• The developed ENMs present a sustainable approach for resource recovery and potential for wastewater remediation.
• Filtration pressure showed minimal impact on EPS recovery and water flux, highlighting process robustness.