Bubble Column with Thin-Film Catalyst Trays for Wastewater Ozonation
Solution Overview
Problem
Existing bubble columns for catalytic ozonation do not effectively accelerate the reaction regime between ozone and pollutants in textile wastewater, leading to inefficient ozone transfer and reaction rates.
Innovation Solution
A bubble column with a thin-film heterogeneous catalyst, featuring trays made of catalyst-coated metal knitted mesh, is designed to increase ozone transfer rates and reaction rates between ozone and pollutants by reducing mass transfer resistance and ensuring stable catalyst contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a bubble column is used for catalytic ozonation of textile wastewater, then ozone transfer from gas phase to liquid phase occurs, but the reaction rate between ozone and pollutants is not sufficiently accelerated
Solution Approach 1:
The patent employs a porous substrate as the support for the heterogeneous catalyst. The porous structure provides large surface area for catalyst deposition, enhancing the contact between ozone and catalyst active sites. This resolves the contradiction by enabling efficient ozone transfer through the porous structure while simultaneously providing sufficient catalytic surface area to accelerate the reaction rate between ozone and textile wastewater pollutants.
Solution Approach 2:
The patent uses a composite catalyst system consisting of metal oxide nanoparticles (such as Fe3O4, γ-Fe2O3, MnO2, Co3O4, CuO, NiO, ZnO, TiO2, or their mixtures) deposited on a porous substrate. This composite structure combines the advantages of the porous substrate (high surface area, good mass transfer) with the catalytic activity of metal oxides, thereby achieving both efficient ozone transfer and accelerated reaction rates, resolving the technical contradiction between productivity and reliability.
2Reliability
If conventional catalysts are used in bubble columns, then catalytic ozonation occurs, but the catalyst does not ensure stable contact with ozone and pollutants
Solution Approach 1:
The porous substrate provides a three-dimensional network structure that stabilizes the catalyst in the bubble column. The porous structure allows ozone bubbles to penetrate and contact the catalyst uniformly throughout the substrate, ensuring stable and consistent catalytic action. This maintains reliable catalyst contact while preserving high treatment efficiency through the large surface area available for reactions.
Solution Approach 2:
The composite structure of metal oxide nanoparticles on porous substrate ensures stable catalyst positioning and contact. The nanoparticles are firmly attached to the porous support, preventing catalyst loss while maintaining high catalytic activity. This composite design ensures reliable and stable contact between catalyst, ozone, and pollutants throughout the treatment process, resolving the contradiction between reliability and productivity.
3Productivity
If thick catalyst layers are used to increase catalytic activity, then reaction rate increases, but mass transfer resistance increases
Solution Approach 1:
The porous substrate enables the use of thin catalyst layers with high surface area. The porous structure provides extensive internal surface area within a thin profile, allowing high catalytic activity without creating significant mass transfer resistance. Ozone can easily diffuse through the porous structure to reach active sites, maintaining low mass transfer resistance while achieving high reaction rates through the large effective surface area of the porous catalyst layer.
Solution Approach 2:
The patent applies catalyst deposition specifically on the porous substrate surface, creating a localized high-activity zone where ozone contact occurs. This localized catalytic layering provides high reaction rates at the gas-liquid interface without requiring thick catalyst layers throughout the entire column, thereby maintaining low mass transfer resistance while achieving high productivity through concentrated catalytic activity at the reaction zone.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The bubble column significantly enhances ozone utilization as an oxidant, increasing ozone transfer rates and reaction rates, thereby improving the efficiency of textile wastewater treatment.
Implementation Method 1
A bubble column for catalytic ozonation with a thin-film heterogeneous catalyst... The action of AOPs is based on the high oxidation potential of reactive oxygen species (ROS), mainly ozone (2.07 V) and hydroxyl radicals (2.8 V)... the catalytic effect of iron compounds in the ozonation process has been proven
Implementation Method 2
increasing the ozone transfer rate from the gas phase to the liquid phase... based on the high oxidation potential of reactive oxygen species (ROS), mainly ozone (2.07 V)
Implementation Method 3
a packing in a form of trays... each of said trays being a circular metal knitted mesh made of wire... coated with a catalyst layer with a thickness of not more than 2 μm comprising a metal oxide
Data Source
Figure 1
Figure 2
AI summary
A bubble column for catalytic ozonation with a thin-film heterogeneous catalyst, intended for a wastewater treatment process by catalytic ozonation, especially textile wastewater, comprises a packing in a form of trays (4) arranged perpendicular to a vertical column axis, wherein each of said trays being a circular metal knitted mesh made of wire with a thickness of at least 0.05 mm, coated with a catalyst layer with a thickness of not more than 2 µm comprising a metal oxide, with a mesh diameter not less than 3 mm, wherein edges of said circular metal knitted mesh are fixed between two rings with an external diameter adapted to the internal diameter (D) of the column of at least 40 mm, said rings being placed one on top of the other and connected with a pipe union. The maximum number of the trays is determined with the formula 0.85⋅Ll wherein L is the column height, l is the distance between the trays (4), and l is equal to 70 x the diameter of an ozone bubble used in the ozonation process. An upper tray (4) is suspended on chains (5), upper ends of which are suspended on hooks attached to the cover (1), whereas lower ends of the chains (5) are connected to hooks mounted in an upper ring of the upper tray (4). The remaining trays (4) are suspended on the chains (5), the upper ends of which are suspended on hooks attached to lower rings of the trays (4) located above, and the lower ends of the chains (5) are connected to hooks attached to the upper rings of the trays (4) suspended on said chains (5). The column is also characterized in that a lower tray (4) of the packing is supported on supports (6), wherein upper ends of the supports (6) are attached to a lower ring of the lower tray (4), wherein lower ends of the supports (6) are supported on a grate placed at the bottom (3) of the column. The upper ends of supports (6) are attached to the lower ring of each of the remaining trays (4), wherein the lower ends of said supports are supported by upper rings of the trays (4) located below.