Dragged-Bed Electrochemical Reactor for Low-Pressure Dye Reduction

The patent extracts and eliminates the harmful reduction agent (hydrosulfite) from the system by replacing it with an electrochemical reduction method using a dragged bed reactor. The electrochemical cell directly reduces dyes at the electrode surface without requiring chemical reduction agents, thereby removing the source of toxic sulfite and sulfate effluents while maintaining effective dye reduction.

The patent employs a dragged bed of conductive granules as an intermediary material that facilitates direct electrochemical reduction of dyes at the electrode surface. The granules act as a physical mediator between the electrode and dye molecules, enabling efficient electron transfer without requiring soluble chemical mediators. This eliminates the need for continuous mediator feeding and complex wastewater treatment systems while maintaining reduction-agent free operation.

The patent implements a dynamic dragged bed system where conductive granules are continuously moved by an upward liquid flow against gravity, maintaining them in a suspended state rather than a static packed bed. This dynamic configuration prevents particle compaction and clogging while allowing the use of fine particles (0.1-1.0 mm) that provide high surface area. The granules are dragged through the electrochemical cell by the liquid flow, ensuring continuous contact with dye molecules without creating excessive pressure drops.

The patent utilizes a dragged bed of porous conductive granules (such as graphite, carbon, or metal particles) as the electrode material. These granules provide an extremely high specific surface area due to their porous structure and small particle size (0.1-1.0 mm). The high surface area to volume ratio of the granular bed enables efficient electrochemical reduction within a compact reactor volume, eliminating the need for large flat electrode surfaces while maintaining high specific reactor power.