09/21/2020 | Cooling Tower Water Treatment | 9 MINUTE READ

What is a Cooling Tower Water Treatment?

If you use a cooling tower within your industrial facility, you will likely need to pair it with a water treatment system, of which there are many different types. The presence of a water treatment system allows for more efficient processes in the cooling tower as well as a longer lifespan for equipment. The problems of untreated water are many and can include the development of corrosion, scaling, organic growth, and fouling.
A standard water treatment system for cooling towers is a combination of technologies that works to get rid of impurities within the blowdown, circulation water, and feed water.
The exact configuration of your water treatment system depends on numerous factors, which include the type of cooling tower within your facility, regulatory requirements pertaining to discharge, the quality of feed water, the exact chemistry of the circulatory water, and the kind of heat exchanger that’s situated in the cooling tower. If you’re currently looking at different water treatment systems for cooling towers, this guide should assist you in making the right decision.

Key Takeaways:

  • Cooling tower’s are essential for your water treatment system within your industrial facilities.
  • We discuss how the cooling tower’s work and how to know if you need one for your type of facility.
  • Understanding the process of a cooling tower will help you understand the water treatment system as well.

How Does a Cooling Tower Water Treatment System Work?

There are many different types of water treatment systems that you can pair with your cooling tower. The processes of these treatment systems can vary depending on the cooling tower requirements as well as the quality of the circulation water and feed water. While these processes can vary, there are some basic steps that are included with most water treatment systems.

Makeup Water Intake

Makeup water is a kind of water that replaces leaked and evaporated water from a cooling tower. This process begins by drawing the water directly from a specific source, which could be well water, city-treated effluent, city water, raw water, and other kinds of surface water. In some situations, the quality of the water may be high enough for you to forego the water treatment process.
In the event that a water treatment system is necessary, the system will be used to remove silica and hardness. It can also be used for the stabilization of the pH levels in the water. You can test the pH levels of water with a pH sensor. When this phase of the water treatment process occurs, the cooling tower evaporation cycles will be stabilized. The bleed rate of the water will also be minimized.

Filtration and Ultrafiltration

The next and arguably most important step of the the process is to filter the water through filtration or ultrafiltration, both of which help to remove suspended particles within the water. These particles can include turbidity, sediment, and other kinds of organic matter. This step of the water treatment process should occur in the early stages to protect the resins and membranes in the system from fouling later on. If you opt for ultrafiltration, it’s possible to remove enough suspended particles to reach less than a single micron of particles.

Water Softening/Ion Exchange

If you find that your makeup water or source water has a high amount of hardness in it, you may need to use ion exchange or water softening processes to get rid of this hardness. This system works by using a softening resin, which will be charged directly by a sodium ion. When the hardness passes through the resin, the iron, calcium, or magnesium molecule will be grabbed by the resin before the sodium molecule is released into the water.
If these contaminants remain in the water, rust and scale deposits will develop, which only serves to reduce the efficiency of the cooling tower. When you want to measure the hardness of the water in your cooling tower, you can do so by identifying the conductivity of the water. These measurements can be taken with a standard conductivity sensor.

Added Chemicals

It’s at this phase of the process that chemicals are typically added to the water. These chemicals can include:

  • Scale inhibitors – Inhibitors like phosphoric acid can prevent the formation of scale deposits
  • Corrosion inhibitors – Inhibitors like bicarbonates are able to neutralize acidity within the water, which helps to protect any metal components
  • Algaecides and biocide – Chemicals like bromine can lessen the growth of biofilms and microbes

If you perform extensive water treatment before reaching this phase of the water treatment process, it’s likely that you won’t need to use as many chemicals, which can save you a significant sum of money.

Side-Stream Filtration

If the water in your cooling tower will be recirculated throughout the system, the use of a side-stream filtration system can help to remove any contaminants that have entered the water via a leak or drift contamination. Around 10 percent of the water that circulates in your cooling tower will filter through this system.

Blowdown Treatment

The final phase of the water treatment process is centered around treating the bleed or blowdown that’s taken from the tower. Although the exact amount depends on how much water is needed for circulation in the cooling plant, some of the water will be recycled and recovered through ion exchange or reverse osmosis. When treating this water, you can remove any solid waste and other contaminants from the water, which allows the treated water to be sent back to the cooling tower and reused.
There are times, however, when the water from the blowdown must be discharged. This discharge must meet regulatory requirements. If water is scarce in your surrounding area, sewer connection fees could be very high. It’s possible to reduce these costs by using demineralization systems. If the effluent is being sent to the environment, the discharge from the cooling tower bleed will need to meet separate municipal discharge regulations.

How to Know If You Need a Cooling Tower Water Treatment for Your Plant

If you want to be certain that your cooling tower operates efficiently and that the system won’t be damaged, it’s highly recommended that you use a water treatment system in your cooling tower. When the water in a cooling tower isn’t treated, the problems that can result include corrosion and the development of scaling. Over time, the buildup of these issues can lead to lessened productivity, more downtime for the plant, and high replacement costs for damaged equipment, all of which you would do best to avoid.
By treating your cooling tower water and removing any contaminants within, you should be able to boost the efficiency and overall success of your cooling tower. There are numerous reasons why you should consider obtaining a water treatment system for your cooling water. For instance, it’s possible that the pH levels or alkalinity levels in the water are too high or too low. Regulating the pH and alkalinity levels is important to maintain the correct balance and chemistry of the water. Lower pH levels should lessen the possibility of scale development. The pH levels in your water should be monitored constantly to keep equipment corrosion and scale formation at bay.
You might also need a water treatment system because of a high amount of total dissolved solids or hardness in the water. The presence of high amounts of calcium bicarbonate and other solids can create substantial scaling in the cooling tower. If these contaminants aren’t removed or prevented altogether, the solids will spread to heat transfers and other piping throughout the tower, which can cause system failure or downtime. Water should be treated regularly to avoid scale formations. When scale develops, it’s very difficult and costly to remove.
You might want to select a water treatment system if there are microorganisms within the cooling tower water. Microbial growth is particularly common in open-recirculating cooling towers. Eventually, bacteria, algae, and fungi can develop if water is left untreated. It’s also possible that legionella will grow, which can cause people to get sick or even die. To maintain water quality, the growth of any harmful bacteria should be taken care of immediately through water treatment.
Water treatment systems may also be necessary in the event that your cooling tower has an insufficient water supply. If water in your area is scarce, local regulations may prevent you from taking too much water or sending too much water back to the environment. As touched upon previously, connecting sewer and water lines can be very costly, which is why you might want to opt for using demineralization systems to reduce some of these costs.
The costs associated with water treatment systems for cooling towers depend on what kind of water is being treated. The equipment needed for treating feed water can cost you around $50,000-$100,000. These costs can increase to as much as $250,000 in the event that a softener is needed. The treatment of circulation water with a side-stream filtration unit can cost around $100,000-$300,000.
When you want to treat tower blowdown, you can expect the costs for a recovery system to be upwards of $300,000. In the event that regulatory requirements dictate zero liquid discharge, the equipment that you need could cost you anywhere from $3-$5 million. If you’re unsure about which treatments are right for your cooling tower, you may want to consult with a water treatment specialist. Water treatment specialists typically work for public utility companies and municipalities, which is where you can find one to assist you.
The use of a water treatment system is practically essential if you want your cooling tower to run efficiently and for the equipment within to remain undamaged. While there are numerous systems that you can use to treat cooling tower water, understanding the treatment process gives you everything you need to know in order to begin the water treatment process.

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Posted by Sensorex on September 21, 2020

Sensorex is a global leader in the design and manufacture of quality sensors for water quality and process applications. The company offers more than 2000 sensor packages for pH, ORP, conductivity, dissolved oxygen, free chlorine, chlorine dioxide, UV transmittance and other specialty measurements, as well as a full line of sensor accessories and transmitters. Its expert technical support engineers solve analytical sensor challenges with custom designs and off the shelf products.

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