Cooling Tower Blowdown: an Environmentally Sensitive Area

By now, you probably know that ARANER is a global brand in matters Industrial Refrigeration Engineering. The firm provides efficient energy solutions, a full range of standard or customized products as well as tailor-made professional solutions and services in a minimal amount of time. In the course of our operations, we have designed and installed many cooling towers, even in environmentally sensitive areas.


Fig 1: ARANER Cooling Tower

We know the different issues that are related to this technology. In this post, we highlight an area that has bedeviled the industry for a long time- blowdown and the environment.

Cooling Tower’s Negative Effects

While industrial facilities hold cooling towers in high regard, the truth is that these gigantic structures have their own environmental side effects. Water use is a huge concern for industries that depend on cooling towers. Together with chillers, cooling towers can consume as much as 90% of water in a facility. This is a necessary problem because cooling towers rely on a steady flow of water to support heat dissipation that is important for industrial processes. Nevertheless, consumption of water equivalent to what a small town uses is not something to ignore. Many regions across the globe have scarce water supply and the last thing industrial facilities in such regions imagine is to waste vast amounts of the precious resource. In such circumstances, ARANER can install an air-cooled chiller system. This setup depends on a current of ambient air instead of a humid air stream (ambient air stream + water spray) used by cooling towers (water-cooled chillers).  Unlike seawater cooled systems, air cooled systems by ARANER are highly efficient, and offer numerous benefits including no chemical costs, low maintenance costs, environmental stability, and avoidance of cooling towers. Locals in some areas have also termed large cooling towers as unsightly. That the structures ruin the natural landscape is a common complaint. Interestingly, other people love the elegant shapes that are cooling towers.

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What Cooling Tower Blowdown Entails

Cooling tower water that leaves the system and ends in the environment is our main concern though. Blowdown is one of the four ways in which the cooling tower loses water. Other mechanisms are Leaks/Overflows, Drift, and Evaporation. Evaporation is the main role of the cooling tower, as it helps transfer heat to the environment. Unfortunately, this process is often accompanied by retention of dissolved solids on the cooling tower components. Popular solids in this case are silica, chloride, magnesium and calcium. As the cooling towers continue to operate, more evaporation of water leads to continual piling of dissolved solids. With time and if unchecked, these solids can form scale on the cooling tower. Blowdown is a necessary measure against this problem.

Fig 2. Evaporative Condenser Process

It is the process of removing these remnant solids and chemicals from the cooling tower system. Many facilities perform this exercise through removal of a section of the concentrated tower water. This water is replaced with fresh water, otherwise known as makeup water.

Blowdown Effects- Compliance is Necessary

Environmental groups have raised concerns about blowdown in the past. Their concerns have grounds, as environmental-cooling tower interaction happens when blowdown discharges into water bodies such as oceans and lakes. Scientists have various ways of establishing the environmental impacts of blowdown. Often, this involves measurement of chemical and physical properties such as temperature, biocide, pH, and water flow rate. In an environmentally sensitive area, it might also be necessary to measure the atmospheric conditions of the area. For these environmentally sensitive areas, pollutants present in the water can be monitored. Dissolved gases such as carbon dioxide, salts such as carbonates and chlorine, and metal ions such as manganese ions are enough to elicit worry in any environmental entity. Cooling towers have also been found to contain bio films and a variety of microorganisms. Compliance to set environmental standards has been more strenuous in recent years, with proprietors being put to task to ensure that cooling tower design and operation is environmentally friendly. For instance, discharge temperature is closely monitored in the Middle East.

Mitigating Environmental Impact

There is no denying that blowdown is an important process for efficiency and longevity of the cooling tower so we might as well plan how to live with it for the near future. By measuring analyzing the conductivity of cooling water, engineers can determine the frequency of blowdown and probably optimize the process. That is the truth; as long as your cooling tower is water based, you can only optimize blowdown. You probably need ARANER expertise in the following areas:

  • Improved feed water quality
  • Solid removal from blowdown water for recirculation
  • Improved cooling tower process

Note also that there are many ways of minimizing release of blowdown into the surrounding environment, and some facilities are already implementing them. Provided the water is biologically and chemically risk free, it can be reused for toilet flushing, general cleaning and so forth. At ARANER, we are committed towards responsible cooling tower design and operations, and we take the necessary measures to ensure that the environment remains safe and sustainable.


Many industrial facilities rely on cooling towers for process cooling and subsequent enhancement of production quality. However, the truth is that the systems can affect the environment negatively through blowdown. Careful monitoring of the process, use of flow meters on flow lines and using reliable water treatment methods are some of the best remedies. ARANER provides expertise needed to install and maintain modern cooling tower systems. For some facilities, it might mean automation of the process to have automatic tracking capability. Let ARANER handle these enhancements in your environmentally sensitive area, as our previous projects are proof of professionalism and success. We are available for any questions regarding cooling tower blowdown and the environment.

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