High-Pressure RO Membrane Boron Removal in Pure Water Systems
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Solution Overview
Problem
In the RO-EDI system, low-pressure RO devices have a low boron rejection rate, leading to increased boron concentration in the treated water when used in multiple stages, which decreases the overall water quality due to concentration effects.
Innovation Solution
Incorporating at least one high-pressure RO device in the second stage or later, with the permeated water from the high-pressure RO being recycled back to the system, and using a third RO device to further treat the concentrated water, thereby diluting and reducing boron concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If low-pressure RO devices are used in multiple stages to improve water recovery rate, then water recovery rate is improved, but boron concentration in treated water increases due to low boron rejection rate
Solution Approach 1:
The RO system is divided into multiple stages with different functions: first stage uses low-pressure RO for high water recovery, second stage uses high-pressure RO specifically for boron removal, and third stage treats concentrated water. This segmentation allows each stage to optimize for its specific function, resolving the contradiction between overall water recovery and boron concentration control.
Solution Approach 2:
Different RO membrane types are applied to different stages based on local requirements: low-pressure membranes in the first stage for high permeation flux and water recovery, high-pressure membranes in the second stage for high boron rejection. This local quality differentiation allows the system to achieve both high water recovery and low boron concentration simultaneously.
2Productivity
If concentrated water is returned to water to be treated to improve water recovery rate, then water recovery rate is improved, but impurity concentration in system increases due to concentration effect
Solution Approach 1:
The harmful concentrated water containing high impurity concentration is extracted from the main water flow and diverted to a dedicated treatment path (third RO device). This separates the high-recovery water stream from the impurity-concentrated stream, allowing the former to be returned to improve water recovery while the latter is treated separately to prevent impurity buildup.
Solution Approach 2:
The third RO device acts as an intermediary treatment unit for concentrated water. It processes the impurity-rich concentrated water from previous stages, converting it into permeated water that can be safely returned to the water to be treated, thus mediating between water recovery goals and impurity control requirements.
3Manufacturing precision
If high-pressure RO device is used in second stage to reduce boron concentration, then boron removal performance is improved, but system complexity increases
Solution Approach 1:
The third RO device merges multiple functions: it treats concentrated water from both the first and second RO stages, and its permeated water is returned to supplement the water to be treated. This consolidation of treatment functions into a single dedicated unit reduces overall system complexity compared to having separate treatment paths for each concentrated water stream.
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
This approach effectively reduces boron levels in the produced pure water without compromising the water recovery rate, maintaining high water quality.
Implementation Method 1
a first reverse osmosis membrane device to which the water to be treated is supplied, a second reverse osmosis membrane device to which permeated water from the first reverse osmosis membrane device is supplied
Implementation Method 2
an electrodeionization (EDI) device is widely used
Data Source
AI summary
A pure-water production device including: a first reverse osmosis membrane device to which water to be treated is supplied; a second reverse osmosis membrane device to which permeated water from the first reverse osmosis membrane device is supplied; an electrodeionization device to which permeated water from the second reverse osmosis membrane device is supplied; a brine tank to which concentrated water from the first reverse osmosis membrane device is supplied; and a third reverse osmosis membrane device connected to the brine tank, wherein the second reverse osmosis membrane device is a high-pressure reverse osmosis membrane device, the brine tank is supplied with at least one concentrated water selected from the group consisting of concentrated water from the second reverse osmosis membrane device and concentrated water from the electrodeionization device, wherein permeated water from the third reverse osmosis membrane device is supplied to water to be treated, is used.