Supercapacitor Desalination System with Zero Liquid Discharge
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Solution Overview
Problem
Current desalination techniques are inefficient in reducing salt concentrations in seawater and brackish water, leading to significant liquid waste and high energy consumption, with existing supercapacitor desalination systems alternating between charging and discharging modes using the same water source, resulting in increased saline discharge.
Innovation Solution
A Zero Liquid Discharge (ZLD) supercapacitor desalination system operates in defined modes, using saturated or supersaturated water during discharging and normal feed water during charging, continuously recycling the concentrate stream to maintain equilibrium and minimize liquid discharge, with energy recovery through bi-directional converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If supercapacitor desalination system alternates between charging and discharging modes using the same water source, then the system can operate continuously, but the saline discharge volume increases and desalination efficiency decreases
Solution Approach 1:
The system divides the water treatment process into two separate streams: a feed water stream for charging mode and a regeneration water stream for discharging mode. This segmentation allows the system to handle fresh water intake and saline discharge independently, preventing the mixing and recycling of concentrated brine that occurs in conventional single-stream systems.
Solution Approach 2:
The patent introduces an intermediary regeneration water stream that serves as a separate medium for the discharging mode. This intermediary stream receives the concentrated ions from the electrodes during discharge, preventing them from being returned to the feed water source and thereby reducing overall liquid waste volume.
2Reliability
If conventional desalination techniques are used to reduce salt concentrations, then salt removal is achieved, but energy consumption increases significantly
Solution Approach 1:
The system employs periodic alternating cycles between charging mode (ion adsorption) and discharging mode (ion release to regeneration stream). This periodic operation allows the supercapacitor electrodes to accumulate ions during charging and then release them to a separate regeneration stream during discharging, achieving continuous salt removal from feed water without requiring high energy input for compression or phase change.
Solution Approach 2:
The patent utilizes changes in electrical parameters (voltage and current) to control the desalination process. During charging, voltage is applied to attract ions to electrodes; during discharging, voltage polarity is reversed or reduced to release ions to the regeneration stream. This electrical parameter modulation enables efficient salt removal with lower energy consumption compared to thermal or high-pressure mechanical methods.
3Productivity
If high-surface-area electrode assemblies are used to concentrate ions, then ion removal efficiency improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The supercapacitor electrodes serve multiple functions: they act as ion adsorption surfaces during charging mode, energy storage elements, and ion release sources during discharging mode. This multi-functionality reduces the need for separate components for each function, thereby simplifying the overall device structure compared to systems that require distinct membranes, resins, or chemical treatment units.
Solution Approach 2:
The system utilizes porous electrode materials with high surface area to volume ratios, such as activated carbon or other porous conductive materials. These porous structures provide extensive ion adsorption capacity within a compact form factor, achieving high ion concentration efficiency without requiring large, complex electrode assemblies. The porosity enables efficient ion access while maintaining a manageable device size.
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 ZLD system reduces liquid waste to near zero, maintains desalination efficiency, and lowers energy consumption by recycling supersaturated water, achieving stable salt removal and precipitation without increasing discharge volume, while minimizing scaling risks and operational costs.
Implementation Method 1
Capacitive deionization is an electrostatic process that operates at a low voltage (about 1 volt for one cell) and low pressure (15 psi). When the brackish water is pumped through a high-surface-area electrode assembly, ions in the water—such as dissolved salts, metals, and some organics—are attracted to oppositely charged electrodes.
Implementation Method 2
This concentrates the ions at the electrodes and reduces the concentration of the ions in the water.
Implementation Method 3
A Zero liquid discharge (ZLD) supercapacitor desalination system of claim 1, wherein the concentrate stream is continuously recycled to maintain an equilibrium between the charging mode and the discharging mode and to minimize liquid discharge
Data Source
AI summary
A desalination system and method of desalinating liquids are provided. The desalination system includes a supercapacitor desalination unit. A first liquid source to be desalinated is provided to the supercapacitor desalination unit while the system is in a charging mode of operation. A second liquid source comprising saturated or supersaturated liquid is provided to the supercapacitor desalination unit when the system is in a discharging mode of operation.