Symmetry to asymmetry: innovative evolvement of a gas-liquid-solid (GLS) separator in UASB/EGSB reactors on a new perspective.

Abstract

The transition from up-flow anaerobic sludge blanket (UASB) reactors to expanded granular sludge bed (EGSB) reactors presents challenges for traditional symmetric critical gas-liquid-solid (GLS) separators, including high spatial occupation, fluid-energy consumption, and reduced separation efficiency. This study introduced a novel GLS separation mechanism based on vortex circulation-induced deposition, agglomeration, and flowback of solid separation. Leveraging this mechanism, an innovative asymmetrical laboratory-scale GLS separator was developed and tested with both granular and flocculent sludge. The new prototype demonstrates superior solid separation performance, achieving 98.3% for granular sludge and 96.0% for flocculent sludge. It features a simple structure and optimized flow paths, resulting in approximately 30% reduction in height and 14.8% less material consumption compared to existing models. Flocculent sludge shows greater sensitivity to operational factors than granular sludge, with higher sludge concentration and smaller fragment size being preferable for high separation efficiency. This mechanism is validated by experimental observations and computational fluid dynamics (CFD) simulations, providing a new perspective on GLS separation and establishing the new model as a promising candidate for UASB/EGSB bio-reactors.