Anaerobic Digestion Performance and Microbial Community Structures in a Pilot‐Scale Up‐Flow Anaerobic Sludge Blanket (UASB) Treating Distillery Wastewater

Anaerobic digestion (AD) is a promising technology for treating high‐strength industrial wastewater while recovering biogas as a renewable energy source. In this study, a pilot‐scale up‐flow anaerobic sludge blanket (UASB) reactor, with a working volume of 225 L, was operated for 130 days to treat raw distillery wastewater. Three different types of distillery wastewater, including centrate, spent caustic, and other low‐strength process wastewater generated during operations (e.g., condensation water), were mixed to balance extreme pH levels and create conditions more suitable for AD. The UASB reactor demonstrated stable performance at an organic loading rate (OLR) of 10.0 kg COD/m 3 /day, achieving a COD removal efficiency of 86%. Average methane yield was more than 71% throughout the operation. Microbial community analysis revealed a significant increase in key syntrophic bacteria and methanogens, with Methanobacterium accounting for 55.8% of the archaeal population. Network and Mantel analyses indicated that syntrophic partnerships play a crucial role in enhancing AD of distillery wastewater under high OLR conditions. Overall, the UASB reactor exhibited high process stability, highlighting its potential for large‐scale application in distillery wastewater treatment.