Buying an Industrial Evaporator? Ask Vendors These Five Questions

Apr 6th 2018

Before investing in an industrial evaporator for your water treatment applications, lower your risks by asking any vendor the following five questions, which cover key topics such as brine disposal, scale prevention, and cost of ownership.

Photo of a multiple effect evaporator - Photo © Evelyn Simak (cc-by-sa/2.0)
Industrial evaporator. Photo © Evelyn Simak (cc-by-sa/2.0)

1. Can you prove evaporator performance through a pilot at my site and provide a performance guarantee that covers changes in water chemistry?

Before investing in a full-scale plant, a small investment in a site pilot will pay off in a matter of months. For unique chemistries, pilots enable you to optimize costs, develop lessons learned, and ensure you have the correct treatment train. This prevents costly changes after full-scale installation start-ups. Ask a vendor how they pilot test, and if they can pilot at your site. Nothing beats operating on live water chemistry that changes along with your operations. 


It is easy for vendors to make a process work behind closed doors or for a short period of time. Ask the vendor to show you how the process runs with variability in inlet conditions, prove that the machine is not scaling over time, and show you a mass balance of all inputs and outputs. Pilots are also an excellent means to test delivery, technical trust, and safety performance of your vendor.


Another tool to protect your investment is a well-written performance guarantee. It will provide a minimum capacity on which you can base your investment decision. Beware of the commonly used simple form, which has plagued many operators in the past, that references guarantees to a single chemistry data set. Your chemistry will change, and when it does, these guarantees can become invalid. Ensure that your performance guarantee accepts wide swings in water chemistry.


At Saltworks, we operate a fleet of mobile and stationary pilots. We also write performance guarantees that remain valid over your broad range of operating conditions.

Photo of a SaltMaker MultiEffect evaporator crystallizer pilot unit
Pilot version of a SaltMaker Evaporator-Crystallizer

2. How can I lower the total cost of ownership of my evaporator plant?

Ensure that you have reviewed opportunities for system optimization that will reduce either your capital or operating expenses. By this, we mean pre-concentration with lower cost technologies before an evaporator, and consideration of incremental cost-value trade-offs of increasing brine concentration. For example, if your TDS is below 80,000 mg/L, with a flow rate above 200 m3/day, ask about pre-concentration technologies.


Saltworks’ experts can help you with this. Modern membrane concentrators, such as our XtremeRO, can concentrate up to 130,000 mg/L, saving evaporator capacity and energy costs. However, if your flows are less than 200 m3/day, having two process plants may not make sense. Instead, it may be worth investing in a slightly larger evaporator.


In addition, you should clearly understand any chemical pre-treatment and the costs per unit inlet. Some vendors will throw a lot of chemicals at the inlet via extensive softening to make conditions easier on their evaporator. Since the chemical costs are included in your operating costs and not in the evaporator’s sale price, vendors can make their evaporator appear at a lower cost, when in fact its total cost of ownership could be much higher than originally anticipated. 

Photo of a conventional technology industrial evaporator
Traditional industrial evaporator technology and infrastructure

At Saltworks, we like to break down the costs per unit inlet ($/m3) into four categories—capital, energy, chemicals, and labor—so that you can see where the costs go.


We work with clients to understand their goals, and cost drivers. We will then run an analysis to project out a cost-optimized treatment train that can inform the total cost of ownership.

3. How do you prevent corrosion and scaling?

Corrosion and scaling are endemic challenges that face evaporator operators. Corrosion and scaling start by suppressing capacity and increasing energy consumption, but can then lead to much downtime and maintenance. Designing for corrosion and scale is essential from day zero, so ask your vendor what they do to prevent these culprits.

Photo of scaling found on the interior surface of pipes
Scaling in a pipe

Our answer to corrosion is to not build everything from titanium or exotic steels—alternative methods exist.


For instance, Saltworks’ SaltMaker family of systems provides such alternatives through smart engineering, with fiber-reinforced plastics. Our answer to scale is to avoid extensive chemical softening of the feed that adds operating costs. The SaltMaker family provides a non-chemical pre-treatment option through non-scaling design and built-in self-cleaning. We design for an evaporator plant to clean itself as it operates, rather than to suffer decaying performance and then complete an annual shutdown that requires significant manual labor for scale removal. Instead, we recommend that you clean as you treat. Read our article on minimizing minimize scale to learn more.

4. What volume reduction can I expect and how do I manage the discharge or reject?

Dealing with discharged reject brine or solids is an important topic and you should evaluate all of your brine disposal options before undertaking an industrial wastewater evaporator project. Explore the change in volume from your input and output streams, then make sure you build a plan to deal with the discharge that conforms with any environmental regulations. Also, evaluate the cost of any brine disposal options and compare them to the costs of further treatment with a crystallizer to produce solids.


Crystallizers offer the option of producing zero liquid discharge solids, rather than concentrated wastewater, that may be better suited to your project needs. In other cases, transporting or handling a liquid slurry that can be pumped, rather than solids, may be preferable. Hybrid evaporator-crystallizer technologies offer the advantage of adaptability to produce either brine or solids in a single plant, and can be upgraded to suit future treatment needs. One example of this kind of technology is the SaltMaker Evaporator Crystallizer, which can reliably operate as an evaporator or crystallizer, with built-in solids management.


Ask the vendor for their recommendations and insights for reject disposal. At Saltworks, we have helped clients source low-cost disposal options and proven safe disposal during pilots. If you pilot, ensure that you see your rejects disposed of via the same mechanism that is intended at full scale. Too often, people wait until their full-scale plants are almost built before considering residual disposal. Start with the final disposal in mind, as it could govern your economics.

Photo of a humidification-dehumidification evaporator
Full-scale version of a Saltworks humidification-dehumidification evaporator

5. Can you provide clear maintenance, operation, and operating cost expectations, and can I visit a reference installation and speak to one of your existing customers?

Know what you are getting into before you invest in an industrial evaporator. Running evaporators requires energy, people, attention, and chemicals. It also requires more management than membrane system assets. Ask vendors to paint a complete picture of installation and operating costs for you, and question every aspect deeply. There is nothing better than visiting an existing installation and talking to operators to secure the full picture.


Coupling site visits with analyzing the full cost of ownership, including trialing a pilot, will set help set up your project for success.

About Saltworks

Saltworks Technologies is a leader in the development and delivery of solutions for industrial wastewater treatment and lithium refining. By working with customers to understand their unique challenges and focusing on continuous innovation, Saltworks’ solutions provide best-in-class performance and reliability. From its headquarters in Richmond, BC, Canada, Saltworks’ team designs, builds, and operates full-scale plants, and offers comprehensive onsite and offsite testing services with its fleet of mobile pilots.

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