# Performance of a Novel Worm-Assisted Membrane Bioelectrochemical System: Electricity Recovery, Sludge Reduction, and Membrane Fouling Mitigation

## TL;DR

A new wastewater treatment system using worms and bioelectrochemical technology improves energy recovery, reduces sludge, and prevents membrane fouling.

## Contribution

The novel integration of aquatic worms with a microbial fuel cell in a membrane bioreactor is introduced for enhanced wastewater treatment.

## Key findings

- The system produced 290 mV and 0.013 W/m² power density while achieving high removal of chemical oxygen demand and ammonia nitrogen.
- Sludge production was reduced by 28.51%, and membrane fouling was mitigated through changes in microbial product properties.
- The W-MBER system showed a 12.93% higher TN removal efficiency compared to conventional MBR systems.

## Abstract

This study developed a novel worm-assisted membrane bioelectrochemical reactor (W-MBER) that integrates aquatic worms and a single-chamber sediment microbial fuel cell into a membrane bioreactor (MBR) to address challenges in energy recovery, sludge reduction, and membrane fouling. The system achieved a stable output of 290 mV at an external resistance of 250 Ω and a maximum power density of 0.013 W/m2 while maintaining high removal efficiencies for chemical oxygen demand (93.57%) and ammonia nitrogen (98.61%). Furthermore, the TN removal efficiency was 12.93% higher than that in the conventional MBR (C-MBR), attributed to the anodic anoxic microenvironment. The synergy of worm predation and the bioelectrochemical process reduced sludge production by 28.51% and extended the filtration cycle by 43.75%, indicating significant sludge reduction and membrane fouling mitigation. Mechanistic analysis revealed that the W-MBER system decreased protein content and protein/polysaccharide ratios in soluble microbial products (SMPs) and extracellular polymeric substances (EPSs), and the hydrophobicity of SMPs, EPSs, and sludge flocs was reduced, resulting in a lower free energy for their interaction with membrane. The foulants in the W-MBER encountered higher energy barriers and lower secondary energy minimums when approaching the membrane, indicating a lower membrane fouling propensity. These results demonstrate the promise of W-MBER for sustainable wastewater treatment.