Integration of anaerobic digestion and electrodialysis for methane yield promotion and in-situ ammonium recovery

Ammonia inhibition is a common issue encountered in anaerobic digestion (AD) when treating nitrogen-rich substrates. This study proposed a novel approach, the electrodialysis-integrated AD (ADED) system, for in-situ recovery of ammonium (NH₄ ⁺) while simultaneously enhancing AD performance. The ADED reactor was operated at two different NH₄ ⁺-N concentrations (5,000 mg/L and 10,000 mg/L) to evaluate its performance against a conventional AD reactor. The results indicate that the ADED technology effectively reduced the NH₄ ⁺-N concentration to below 2,000 mg/L, achieving this with a competitive energy consumption. Moreover, the ADED reactor demonstrated a 1.43-fold improvement in methane production when the influent NH₄ ⁺-N was 5,000 mg/L, and it effectively prevented complete inhibition of methane production at the influent NH₄ ⁺-N of 10,000 mg/L. The life cycle impact assessment reveals that ADED technology offers a more environmentally friendly alternative by recovering valuable fertilizer from the AD system.