Evaporator vs Closed-Loop Recycling for Pretreatment Wash Water
An evaporator reduces how much pretreatment wash water you haul, but it doesn't make the water usable again. It burns energy to boil or air-dry the water off, and what's left still has to be tested and disposed of. Closed-loop recycling filters the water and puts it back to work, with no process discharge.
If you're choosing between the two, the deciding questions are energy, what's left over, and whether you want to buy water again.
How does a wastewater evaporator work?
The evaporator heats wash water, or blows air across it, until the water leaves as vapor. Dissolved chemistry, oils and solids stay behind as a concentrate. Industry writers describe mechanical evaporation as energy-intensive and capital-intensive, so each application needs a careful look (Wastewater Digest).
What does an evaporator leave you to manage?
The concentrate. Connecticut's evaporator guidance says the concentrates removed from evaporators need a hazardous waste determination and must be managed to match it. It also calls for testing the wastewater before it goes in (Connecticut DEP).
The same guidance notes that an evaporator venting vapor to the air may need an air permit in some cases. Rules vary by state, so check with your state agency.
How do evaporators and closed-loop recycling compare?
Question | Evaporator | Closed-loop recycling (CPR Systems) |
What happens to the water | Leaves as vapor; you buy fresh water to replace it | Recovered and reused in the wash |
What happens to the chemistry | Concentrated and left behind for disposal | Stays in the loop; you add chemistry to hold titration |
Ongoing energy | Heat or air flow to drive off water, every gallon | Heat for the hot water washer only |
Testing and paperwork | Hazardous waste determinations on what goes in and what comes out (CT DEP) | No process discharge |
Effect on chemistry costs | None; chemistry still leaves with the concentrate | Reduces chemistry and water use by over 80% compared to wash and haul operations |
When does an evaporator make sense?
An evaporator can fit a shop with a small, steady volume and an existing disposal route for the concentrate.
If your main costs are chemistry and water, an evaporator doesn't touch them. Recycling does, because the chemistry you've already paid for stays in use.
Weighing wand systems instead? See Spray Wand Pretreatment Systems Compared.
Frequently asked questions
Is an evaporator a zero discharge system?
It can avoid a sewer discharge, but the water still leaves as vapor and the concentrate still leaves as waste. Closed-loop recycling keeps the water in the process.
Can I add recycling to the washer I already have?
Yes. Tell us about your washer and chemistry, and we'll tell you whether a retrofit or a replacement fits better. Our repair or replace guide covers the trade-offs.
Does recycling work with zirconium as well as iron phosphate?
Yes. The equipment is set up for the chemistry you run. See iron phosphate vs. zirconium.
See what recycling saves you
Our savings calculator compares your current water, chemistry and disposal spend with a closed-loop system. Send us your spec. Get a quote.
For the rules behind each disposal route, see powder coating wash water disposal: EPA rules and compliance options.
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