A more sustainable solution for deionisation: EDI vs mixed bed systems
by Yasmin Refaei, Director of Sales at Xylem
Across the globe, pressure to cut costs and minimise environmental impact is mounting for power plants. With the focus firmly on increasing operational efficiency to meet these goals, it’s time to demand more from water treatment and embrace the benefits of advanced technology. Yasmin Refaei, Director of Sales at Xylem, shines the spotlight on ultrapure water generation and discusses the advantages of using continuous electrodeionisation (CEDI) vs mixed bed systems to increase sustainability.
Effective water treatment is critical to the power industry. One example is the generation of ultrapure water. Deionised water is used as makeup for boilers, to produce steam to drive turbines. Without it, contaminants in untreated water can cause scaling and corrosion, leading to reduced efficiency in boilers and turbines. Ultimately, this reduces service life and can lead to system failure and plant downtime.
Traditionally, power plants have used mixed bed systems to produce ultrapure water. This chemically regenerated ion exchange process uses ion-attracting resins to remove contaminants. It involves a regeneration process, which has to take place regularly as the resins become loaded with contaminants and lose their effectiveness. Regenerating these resins consumes both caustic and acid – hazardous substances that require special storage and handling – and creates a waste stream to manage.
Today, CEDI systems offer an alternative technology that increases plant sustainability, while eliminating safety risks and delivering improved whole life costs. CEDI is an electrochemical process that uses self-regenerating ion exchange resins to purify water. The ion exchange resins continuously regenerate, meaning purity remains at a consistent, high level.
A more sustainable solution
CEDI is a total game changer when it comes to increasing sustainability. The process eliminates the need for traditional ion exchange resin beds and chemical regeneration, so there’s minimal chemical use. Its waste stream, instead of being transported offsite for processing, can be managed internally and, in some cases, treated for reuse. Unlike with mixed bed systems, there’s no backwash required, saving water consumption and waste. With CEDI systems, wastewater is recycled back to feedwater.
In addition, a CEDI system has a much smaller footprint for the same flow rate than large mixed bed systems. This saves space, reduces engineering and construction requirements, and eliminates the need to find storage room for chemicals.
In fact, at all points throughout a CEDI system’s lifespan it’s a more sustainable option for power plants than traditional mixed bed systems. This includes ongoing maintenance requirements. With CEDI this is significantly reduced, as there’s no need for daily maintenance and specially trained staff to dose chemicals. It also results in less downtime compared to older systems with regeneration or exchange cycles.
Eliminating chemical risks
One of the key benefits of CEDI is that it’s safer for the workforce and the environment. The hazardous chemical storage and handling that’s required with mixed bed systems is a significant safety risk. With CEDI, and no need for chemical regeneration, plants can switch the focus from mitigating this risk to eliminating it. This also serves to protect the environment, as there’s no risk of chemicals entering the local water.
Better for the bottom line
CEDI systems are not just operationally superior, they are more cost-efficient long-term. OPEX is low thanks to its energy efficiency, low maintenance requirements and chemical free process. When compared to mixed bed deionisers, Xylem’s Ionpure® systems offer annual cost savings as high as 77%. They are also far more cost-efficient than rental units too, offering up to 91% annual OPEX savings.
Demand more
A growing number of power plants worldwide are embracing the benefits of CEDI technology and it’s clear to see why. It’s possible to achieve a consistent flow of superior quality water, while meeting critical sustainability and safety targets, all while cutting lifecycle costs. It’s time to demand more from your deionisation technology.