As demand for fresh water increases, more and more industries and municipalities are turning to Reverse Osmosis (RO) as a means of water treatment. RO is an efficient process for removing dissolved solids and contaminants from water, but it comes with a major drawback: the production of a waste stream known as RO reject, that today can be treated and concentrated by DESALT Electrodialysis Reversal (EDR).
The Problem of RO Reject Concentration
RO reject is concentrated brine that can be difficult and expensive to dispose of safely. In many cases, it must be hauled away and disposed of off-site, which can be costly and environmentally unsustainable. As such, a number of technologies have been developed to help manage the concentration of RO reject, such as DESALT electrodialysis reversal equipment (EDR).
Overview of DESALT Electrodialysis Reversal Equipment for RO Reject Concentration
DESALT electrodialysis reversal equipment is a type of electrodialysis system that can be specifically designed to concentrate RO reject. It works by using an electric current to separate ions in a solution, creating a concentrated brine stream and a purified water stream.
DESALT equipment is made up of a series of ion exchange membranes and electrodes that are arranged in a stack. The feed water (in this case, the RO reject) is passed through the stack while an electric current is applied. This causes the ions in the water to migrate towards the electrodes of the opposite charge, where they are removed from the water stream.
The result is two separate streams: a concentrated brine stream that contains the removed ions, and a purified water stream that is free of those ions. The purified water can be recycled back into the RO system, while the concentrated brine can be disposed of or further treated as necessary.
The concentrated brine stream is typically around 20-30% of the initial feed water volume and contains the ions that have been removed from the water stream. The purified water stream can be recycled back into the RO system, reducing overall water usage.
Electrodialysis Membranes for RO Reject Concentration
The use of both cation and anion exchange membranes in electrodialysis reversal equipment enables the selective removal of salts from RO reject concentrate. As the solution passes through the membranes, the charged ions are attracted to the opposite charge on the membrane and are retained, while the water and uncharged solutes pass through the membrane.
Cation exchange membranes contain negatively charged groups that attract positively charged ions, such as sodium (Na+) and calcium (Ca2+), while repelling negatively charged ions, such as chloride (Cl-) and sulphate (SO42-). Conversely, anion exchange membranes contain positively charged groups that attract negatively charged ions and repel positively charged ions.
Electrodialysis membranes are available in a variety of configurations and materials, including ion exchange resins, porous polymeric membranes, and composite membranes. The choice of membrane material and configuration depends on the specific application, including the composition of the RO reject concentrate and the desired level of desalination.
Factors Affecting Electrodialysis Performance for RO Reject Concentration
Several factors can affect the performance of electrodialysis reversal equipment for RO reject concentration. These factors include:
Concentration and composition of the feed solution: The concentration and composition of the RO reject concentrate can impact the selectivity and efficiency of electrodialysis membranes. Higher concentrations of dissolved solids can result in fouling of the membranes and reduced performance;
Membrane fouling: Fouling of the electrodialysis membranes can occur due to the accumulation of solids, organics, and other contaminants on the surface of the membrane. Fouling can reduce the efficiency and lifespan of the membranes and may require chemical cleaning or replacement of the membranes;
Current density: The current density applied to the electrodialysis system can impact the selectivity and efficiency of the membranes. High current densities can result in increased fouling and reduced performance, while lower current densities may require longer treatment times;
Operating temperature and pH: The operating temperature and pH of the RO reject concentrate can impact the performance and lifespan of the electrodialysis membranes. Elevated temperatures and extreme pH conditions can result in membrane degradation and reduced performance.
Advantages of Using DESALT Electrodialysis Reversal Equipment for RO Reject Concentration
There are several advantages to using DESALT electrodialysis reversal equipment to manage RO reject concentration:
Efficient: DESALT can achieve a recovery rate of up to 95%, meaning that up to 95% of the water in the RO reject can be recovered and reused.
Low energy consumption: DESALT uses less energy than other technologies, such as thermal evaporation, to concentrate RO reject.
Modular design: DESALT is a modular system that can be customized to meet the needs of different applications and volumes of water.
Low operating costs: DESALT has low operating costs compared to other technologies, such as evaporators, due to its low energy consumption and low maintenance requirements.
Environmentally sustainable: By recovering and reusing water, DESALT helps to reduce the overall water footprint of a facility or municipality. It also reduces the amount of waste that must be disposed of off-site.
Flexibility: DESALT can be used for a variety of applications beyond RO reject concentration, including desalination of brackish water and treatment of industrial wastewater.
Applications of DESALT Electrodialysis Reversal Equipment in Ro Reject Concentration
DESALT electrodialysis reversal equipment has a wide range of applications in industries and municipalities that use RO as part of their water treatment process. Some of the most common applications include:
Municipal water treatment: DESALT can be used to manage RO reject produced during the treatment of municipal water supplies.
Industrial wastewater treatment: DESALT can be used to concentrate and treat wastewater produced by industrial processes.
Power generation: DESALT can be used to manage RO reject produced during the treatment of water used in power generation.
Mining: DESALT can be used to treat and concentrate water used in mining operations.
Find more applications for electrodialysis reversal on our website.
Comparison Of Desalt Electrodialysis Reversal Equipment With Other Solutions for RO Reject Concentration
While DESALT electrodialysis reversal equipment is an effective and efficient solution for managing RO reject concentration, there are other technologies available as well. Some of the most common alternatives include:
Thermal evaporators: Thermal evaporation is a process in which water is heated to produce steam, which is then condensed to create purified water and a concentrated brine stream. While it is effective for concentrating RO reject, it is also very energy-intensive and expensive to operate.
Membrane filtration: Membrane filtration systems, such as ultrafiltration and nanofiltration, use specialized membranes to remove contaminants from water. While they are effective for treating water, they are less efficient for concentrating RO reject than electrodialysis systems like DESALT.
Compared to the previous technologies, DESALT offers a combination of efficiency, low energy consumption, and low operating costs that make it a compelling choice for managing RO reject concentration.
Conclusion
DESALT electrodialysis reversal equipment is a powerful solution for managing RO reject concentration in industries and municipalities.
By using an electric current to separate ions from the water stream, DESALT can recover most of the water in the RO reject, reducing overall water usage and waste disposal costs. It is also more energy-efficient and cost-effective than many other technologies, making it a suitable choice for a wide range of applications.
For more information about DESALT EDR technology kindly get in touch with our team.
FAQs
Q: Is DESALT suitable for treating and concentrating all types of RO reject?
A: Yes, DESALT electrodialysis can be customized to treat and concentrate RO reject from a variety of sources and with varying levels of dissolved solids.
Q: How much energy does DESALT consume compared to other technologies?
A: DESALT electrodialysis consumes less energy than thermal evaporation and other technologies commonly used for concentrating RO reject.
Q: What are the main benefits of DESALT electrodialysis reversal equipment?
A: The main benefits of DESALT electrodialysis reversal equipment include high salt rejection rates, low energy consumption, scalability, and ease of operation and maintenance.
Q: How does DESALT electrodialysis reversal equipment compare to other concentration technologies?
A: DESALT electrodialysis reversal equipment offers several advantages over other concentration technologies, including lower energy consumption, reduced environmental impact, and a lower total cost of ownership.
Q: What industries can benefit from DESALT electrodialysis reversal equipment?
A: DESALT electrodialysis reversal equipment can be used in a variety of industries, including water treatment, food and beverage, and chemical processing. The equipment can be used in any application that require RO reject concentration.