Two-Stage RO and EDI Boron Removal for Ultrapure Water
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Solution Overview
Problem
Existing methods for boron removal in water treatment systems, such as using high-pressure RO membranes or adjusting pH, lead to increased energy consumption and maintenance costs without achieving sufficient boron removal rates.
Innovation Solution
A water treatment system comprising an extra low-pressure RO membrane device followed by an EDI device with a specific EDI stack configuration, including an anion and cation exchange resin arrangement, to enhance boron removal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-pressure RO membrane devices are used to increase boron removal rate, then boron removal rate improves to 80-90%, but pump power consumption increases
Solution Approach 1:
The patent changes the operating parameters by using extra low-pressure RO membranes instead of high-pressure membranes, operating at lower pressure (0.5-2.0 MPa) to achieve boron removal rates of 85-95% without the high energy consumption associated with high-pressure systems
Solution Approach 2:
The patent divides the water treatment process into multiple stages: first stage using extra low-pressure RO membranes for preliminary boron removal, second stage using EDI devices for final polishing. This segmentation allows each stage to operate at optimal parameters, achieving high overall boron removal (99.9%) while managing energy consumption efficiently
2Manufacturing precision
If pH of water is adjusted to alkaline side (pH 9 or more) to improve boron removal rate, then boron removal rate improves, but chemical injection facilities and chemical replenishment management are required, resulting in increased management costs
Solution Approach 1:
The patent employs EDI (Electrodeionization) devices that automatically remove ions including boron through electrical fields and ion-exchange membranes without requiring external chemical additives. The system self-regulates the water composition through electrochemical processes, eliminating the need for chemical injection facilities and manual chemical replenishment management
Solution Approach 2:
The patent replaces the chemical-based boron removal approach (pH adjustment requiring chemical injection) with an electrochemical approach using EDI devices. The mechanical/electrical system of ion-exchange membranes and electrical fields substitutes for the chemical system, achieving boron removal without chemical management complexity
3Manufacturing precision
If alkali is added to improve boron removal rate through RO membrane, then boron removal rate improves, but degradation of RO membrane accelerates, raising the concern that RO membranes will need to be replaced more frequently
Solution Approach 1:
The patent changes the chemical environment parameters by avoiding alkaline pH adjustment and instead using neutral or slightly acidic conditions with extra low-pressure RO membranes. This parameter change protects the membrane from alkaline degradation while maintaining effective boron removal rates of 85-95% in the first stage
Solution Approach 2:
The patent segments the boron removal process so that the RO membrane stage operates under mild conditions (extra low-pressure, neutral pH) to preserve membrane life, while the EDI stage handles the final boron removal. This segmentation allows the RO membrane to serve longer without chemical degradation while still achieving high overall boron removal through the combined system
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 system achieves boron removal rates up to 99.9% without significant energy or maintenance drawbacks, meeting ultrapure water standards for semiconductor manufacturing.
Implementation Method 1
The use of reverse osmosis membrane devices (hereinafter referred to as RO membrane devices) is known to be capable of removing boron
Implementation Method 2
The use of electro-deionization deionized water production devices (hereinafter referred to as EDI devices) is known to be capable of removing boron
Implementation Method 3
an EDI stack for high purity in which a lowermost layer of a desalination chamber is filled with at least an anion exchange resin and an adjacent concentration chamber via a cation exchange membrane that partitions the desalination chamber is filled with at least a cation exchange resin
Data Source
AI summary
A water treatment system for removing at least boron from treated water includes RO membrane devices that include an extra low-pressure RO membrane, and EDI devices that are arranged to follow the RO membrane devices and that include an EDI stack for high purity in which at least an anion exchange resin fills a bottom layer of a desalination chamber and at least a cation exchange resin fills an adjacent concentration chamber via a cation exchange membrane that partitions the desalination chamber, wherein the RO membrane devices are RO membrane devices in two stages, and an extra low-pressure RO membrane is arranged in at least one of the first and second stages.