Dual Membrane Brine Concentration for High-Recovery Desalination
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Solution Overview
Problem
Existing desalination technologies face challenges with high energy consumption, brine volume management, and environmental impact due to high-concentration brine disposal, as well as limitations in membrane durability from scale deposition at high recovery rates.
Innovation Solution
A dual nano-filtration-reverse osmosis brine concentration system utilizing hollow fine fiber forward osmosis (HFF FO) to treat two brine streams, one rich in divalent ions and the other in monovalent ions, allowing for efficient concentration up to 250,000 ppm, facilitating mineral extraction and zero liquid discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thermal process-based systems (MVC or TVC) are used for brine concentration, then high brine concentration (250,000 ppm) can be achieved, but energy consumption becomes excessively high (24 kWh/m3)
Solution Approach 1:
The brine concentration process is divided into multiple stages with progressively higher operating pressures. The system uses a first stage operating at lower pressure (e.g., 30-50 bar) and a second stage operating at higher pressure (e.g., 80-100 bar), allowing each stage to operate within optimal efficiency ranges rather than requiring one stage to handle the entire concentration range at excessively high energy input
Solution Approach 2:
The system dynamically adjusts operating parameters including pressure, flow rates, and stage configuration based on feed brine characteristics and desired concentrate concentration. This allows optimization of energy consumption across varying operational conditions while maintaining effective brine concentration
2Quantity of substance
If recovery rate is increased beyond 50% in SWRO systems, then brine volume is reduced, but osmotic pressure approaches membrane bursting levels and power consumption increases
Solution Approach 1:
The recovery process is segmented into multiple stages, with each stage operating at optimized pressure levels. This allows the system to achieve high overall recovery rates by progressively concentrating brine through stages rather than attempting single-stage high recovery, keeping osmotic pressure differences within manageable ranges at each stage
Solution Approach 2:
The system changes operating parameters (pressure, temperature, flow rate) across different stages to optimize performance. By adjusting these parameters dynamically, the system can achieve high recovery rates while managing osmotic pressure effects and minimizing power consumption increases
3Quantity of substance
If recovery rate is increased beyond 50% in SWRO systems, then brine volume is reduced, but membrane durability deteriorates due to scale deposition
Solution Approach 1:
The concentration process is divided into stages with progressively higher operating conditions. This segmentation allows intermediate cleaning and maintenance between stages, preventing cumulative scale deposition that would occur in single-stage high recovery systems, thereby extending membrane life
Solution Approach 2:
The system performs preliminary actions such as feed pretreatment and anti-scalant dosing before brine enters the membrane stages. This preliminary protection reduces scale formation on membranes, enabling higher recovery rates without compromising membrane durability
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 enhances energy efficiency, reduces brine volume, and enables commercially viable mineral extraction while maintaining membrane integrity, achieving higher recovery rates and lower specific power consumption.
Implementation Method 1
hollow fine fiber forward osmosis (HFF FO) to treat two brine streams
Implementation Method 2
utilizing hollow fine fiber forward osmosis (HFF FO) to treat two brine streams, one rich in divalent ions and the other in monovalent ions, allowing for efficient concentration up to 250,000 ppm
Implementation Method 3
dual nano-filtration-reverse osmosis brine concentration system
Data Source
AI summary
A system and method for producing very high concentration brine streams from which commercially efficiently obtained minerals may be obtained is produced by a dual membrane brine concentrator system (DTRI Concentrator). The system includes a nano-filtration system which removes divalent ions from the seawater, a brine concentrator such as a hollow fine fiber forward osmosis system which receives and further concentrates the brine rejected from the nano-filtration system, a SWRO system which receives the NF system permeate and removes monovalent ions, and another brine concentrator which further concentrates the brine rejected from SWRO system. Various permeate and reject brine flow may be forwarded through the Dual Membrane Brine Concentrator system, and multiple stages of the system components may be used, to enhance brine concentration and improve system efficiency.