# Sustainable recovery from pig slurry using ionic liquid microbial fuel cells and microalgae consortia

## TL;DR

This study introduces a sustainable method to manage pig slurry by combining microbial fuel cells and microalgae-bacteria systems to recover nutrients and generate energy.

## Contribution

The novel integration of ionic liquid microbial fuel cells with microalgae-bacteria consortia for raw pig slurry treatment is presented.

## Key findings

- The system achieved 50% COD removal and generated 57.27 ± 10.99 mW·m⁻² of power using ionic liquid microbial fuel cells.
- The combined treatment recovered up to 67% COD, over 99% N-NH4+, and 65–85% P-PO43− from pig slurry.
- Biomass productivity from treated slurry matched levels achieved with chemical fertilizers.

## Abstract

Pig slurry management has emerged as a pressing environmental challenge in the context of rapid population growth and intensified livestock production, highlighting the need for sustainable recovery technologies. While microalgae–bacteria (MB) systems offer promising opportunities for nutrient recycling, the high turbidity of raw pig slurry (PS) typically limits their direct application. This study proposes an innovative two-step treatment that combines microbial fuel cells (MFCs) with MB consortia to enhance both pollutant removal and resource recovery from raw PS with COD levels exceeding 18,000 mg·L⁻1. Unlike conventional designs relying on perfluorinated membranes, the MFCs employed an ionic liquid [N8-10,8–10,8–10,1+][Cl−] as a proton exchange medium, achieving 50% of COD removal and generating 57.27 ± 10.99 mW·m⁻2. The effluent was subsequently treated with MB consortia, yielding biomass productivities of 0.1 to 0.2 g·L⁻1·day⁻1, comparable to chemical fertilizer-based controls. Cell density with pre-treated and untreated pig slurry also matched control levels. In pollutant recovery, the combined microbial fuel cell and microalgae-bacteria treatment achieved up to 67% recovery of COD, over 99% of N-NH4+, and between 65 and 85% of P-PO43−. These findings highlight the potential of integrating MFCs with MB consortia as a strategy for raw pig slurry management, t-ransforming waste into renewable energy and bioresources.

• Pig slurry is transformed into biomass and bioenergy using sustainable technologies

• Microalgae-bacteria consortia enhance nutrient recovery and water treatment

• Ionic liquid microbial fuel cells support energy generation and COD reduction