XtremeUF Ceramic Ultrafiltration
XtremeUF ceramic ultrafiltration removes oils, grease, precipitated by-products, particulate, microbes, and suspended solids.
Cooling Tower Blowdown Water Recovery
Increase Cooling Tower Cycles and Treat Blowdown
Saltworks can help you reduce water usage by treating inlet water or recovering water from blowdown. We study your problem to help you optimize costs, recover water, and explore brine management strategies.
Cooling Tower Water as a Resource
Cooling towers are widely used in industrial processes to reject heat by evaporating water to atmosphere. They represent one of the largest industrial water loads and hold untapped water recovery potential—once their chemistry is understood.
As cooling tower water is cycled and evaporated, total dissolved solids (TDS), chlorides, and scaling ions concentrate, while biological activity may increase. Chemical additives including corrosion inhibitors, biocides, and antiscalants may be used.
Operators periodically ‘blow down’ the cooling tower water and replace it with fresh water. Permissible blowdown concentrations, and resulting cooling tower cycles, may be governed by air regulations for saline drift, corrosion limits within the cooling circuit, scaling limits, or sewer discharge limits. Blowdown cycles can be reduced or blowdown water recovered by advanced treatment options.
How to Reduce Water Draw and Recover Water
After optimizing an existing system, operators generally have three choices to reduce water consumption:
- Purify inlet water to reduce TDS and chlorides, which boosts cycles (Option A)
- Treat cooling tower blowdown to recover freshwater and produce low-volume brine or even zero liquid discharge (ZLD) solids. (Option B).
- Surgically treat a specific contaminant of concern, such as scaling ions, to enable greater cooling tower cycles.
More on Treatment Options
In most cases, treating cooling tower inlet water will result in superior economics compared to treating blowdown water, which may include chemical additives and constituents ‘scrubbed’ from the atmosphere. Options include:
- Reduce make-up water chlorides and TDS with XtremeRO: Remove total dissolved solids and chlorides via inlet desalination, maximizing water recovery up to sewer discharge limits or your economic break-even point.
- Remove make-up water scaling ions with BrineRefine: Our automated chemical softening system can selectively remove many scaling species, such as calcium, sulfate, and silica, allowing you to run your tower at higher cycles as a result.
- Treat CTB with Minimal Liquid Discharge (MLD) solutions: Saltworks’ robust MLD membrane systems are designed to protect and preserve membrane health in the face of scaling ion and organic fouling caused by upstream chemical additives.
- Manage brine reject: As water is concentrated, so are the dissolved solids and organics. Saltworks offers brine management options and solutions, including zero liquid discharge systems when warranted.
A Primer on Blowdown Treatment
Cooling tower blowdown (CTB) can present unique water recovery challenges, largely owing to the chemical additives employed. Reverse osmosis is the workhorse of industrial freshwater recovery, however, its membranes may be fouled by the corrosion inhibitors, biocides and/or scaling ions present in many cooling towers.
While there is no one-size-fits-all treatment approach, Saltworks has developed and thoroughly tested a robust suite of technologies that reliably and cost-effectively recover water from CTB.
The block flow diagram below shows how to treat cooling tower blowdown in three key steps, each with increasing water recovery. Learn more in our CTB case study which includes a sample mass balance.
Saltworks helps clients understand which steps suit their system and the economics of pushing water recovery. We design and build the process plants with an in-depth understanding of the technology limits, and capital and operating costs. The three steps of CTB treatment are described below.
A.) Primary Treatment & Water Recovery: typically, 80%.
Water is pre-conditioned first to remove suspended solids and then organics, such as azole-based corrosion inhibitors, which could foul the downstream RO. Preconditioning equipment may involve Saltworks’ filtration solutions and our Xtract-TOC absorption vessels. Primary water recovery is then achieved often with our lower-pressure XtremeRO until ionic scaling limits are reached.
B.) Secondary Water Recovery & Minimal Liquid Discharge (MLD): typically, 98% cumulative.
After effective primary water recovery, scaling limits for silica or calcium sulfate are often reached. These and other scaling ions may be removed through chemical precipitation via Saltworks’ BrineRefine and XtremeUF. After this, our higher-pressure XtremeRO units recover water until either the brine discharge or RO system osmotic pressure limits are reached. If brine cannot be discharged from the site, some will consider trucking the low-volume solution (2% of inlet) to a discharge facility or taking the next step to ZLD.
C.) Final Water Recovery & Zero Liquid Discharge: almost 100% water back with no liquid brine.
Zero liquid discharge (ZLD) involves squeezing every last drop of water from the brine and producing solid salts for safe final disposal. Saltworks’ modular self-cleaning SaltMaker Crystallizers are well suited for this service. The objective of this final step is less about water recovery and more about brine management.
Get Specific and Analytical
Saltworks’ team of industrial desalination professionals can review your cooling water case and work with you to understand and price options based on a detailed analytical approach.
Learn more about how to achieve 99% water recovery from cooling tower blowdown from this summary of an award-winning peer-reviewed publication.
Contact us to discuss how your cooling tower performance can be enhanced and to explore increased water recovery and cost trade-offs, or to explore brine management options.
Related Products
BrineRefine Chemical Reactor
BrineRefine is a continuous stirred tank reactor (CSTR) that executes diverse chemical reactions efficiently and with precision.
XtremeRO Reverse Osmosis & Nanofiltration
Our XtremeRO and OARO provide industry-leading recovery and reliablity. Concentrate brine, reduce discharge volumes, recover freshwater and more.
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