The United States Pharmacopeia (USP) segments the use of water in pharmaceuticals into three broad families: water for injection (WFI), purified water & drinking water. All these categories have costs associated with them and have specific standards based on their categorization. Water for injection (WFI), being the purest water possible, is the most difficult and costly to achieve. With very specific acceptance criteria, the efficiency of the water purification system must be optimal in order to offer a continuous and efficient performance.

Pharmaceutical water purification systems are particularly complex and can have complications related to their use. To learn more about how these systems work, visit this article! Among the challenges faced by pharmaceutical companies, biofilm formation can be a recurring problem when a system is not disinfected in the right way.

Whether we are talking about thermal or chemical disinfection, each of them has its advantages and disadvantages. Therefore, it is important to choose the right technology to best meet the specific needs of your business. To help you select a disinfection method, here is a presentation of the most widespread disinfection technologies in the pharmaceutical industry.


Thermal Disinfection

For many years, pharmaceutical companies have been adopting thermal disinfection to avoid adding chemicals to water, since the addition of any product can result in the presence of chemicals in the final product. With thermal treatment, no substances are added, the temperature changes are the only source of disinfection.

Some pharmaceutical companies opt for a water treatment system operating at high temperature, this technique allows to decrease the chances of contamination radically. However, when referring to thermal disinfection, the system must operate a periodic and temporary disinfection. These periodic disinfections last approximately 4 hours and must be done daily or weekly.

The pharmaceutical industry and its organizations have established the standard that for an optimal treatment, the system must be exposed to a temperature of 80°C for 30 to 60 minutes. It is important to note that despite optimal disinfection, hot water is not known to remove endotoxins from water, so depending on the needs and standards to be followed, thermal disinfection must sometimes be accompanied by other technologies. Furthermore, thermal disinfection has proven to be effective against biofilms formation, but won’t affect already established biofilms.

Thermal treatment must be performed more frequently to avoid contamination. Moreover, it requires the addition of a component responsible for temperature changes: the heat exchanger. This component will automate the disinfection on site while controlling the temperature variations at a rate of 5°C per minute. Although the membranes used in a thermal disinfection system use a particular adhesive, the purpose of controlling the rate of temperature change is to reduce damage to the membranes.

There are many advantages to thermal treatment. Among these, we can think of the respect of the environment since no chemical product is used. Also related to the absence of chemical products, the costs and risks related to the handling, transport and use of these products are reduced. Finally, being a solution accepted by the different pharmaceutical standardization organizations, thermal treatment is a simple and efficient alternative, but it significantly increases the energy costs of a system.



Chemical Disinfection

Chemical disinfection works on a fairly simple principle: the addition of an oxidizing agent to the water. These oxidizing agents are very varied, we can think of peracetic acid (C₂H₄O₃), chlorine (Cl), hydrogen peroxide (H2O2), ozone (O₃), and many others! Each of these agents has special features that justify their use.

However, the two most common oxidants used to purify water in pharmaceutical sectors are chlorine and its derivatives and ozone. Most of the time, an automatic dosing system is added to the water purification system to avoid unnecessary handling of chemicals and to optimize operations.




Chlorination is the principle of using chlorine or a product containing chlorine to disinfect substances in water. This technique has been used for almost 100 years and has proven to be effective against many types of bacteria and viruses; however, it is not universal and may not be effective against certain contaminants such as protozoan cysts. On the other hand, if these types of contaminants are not a problem, chlorination is relatively inexpensive compared to its effectiveness.

One of the advantages of chlorination is that it can be done at any time during the water purification process. Whether it is done before entering the water purification system, before the filtration process or as a final treatment, it will positively affect the quality of the final product. However, the timing of the disinfection will have an impact on the final cost since the more contaminants present in the water, the higher the chlorine concentration and the longer the contact time. This is why, most of the time, chlorination is performed as a final disinfection.

Several chlorine derivatives are available on the market today, the most common are chlorine gas, calcium hypochlorite and sodium hypochlorite. Chlorine gas is a 99.8% pure chlorine concentrate. Due to its high concentration, this derivative is particularly dangerous to use since its inhalation can cause complications and even death. On the other hand, its high concentration makes chlorine gas a very effective disinfection product.

Calcium hypochlorite is very stable and can be stored for a very long time. Despite its solid form and stability, its storage must be thoughtful since it must be dry and must not be in contact with wood, fabric, or oil, otherwise it can create an explosion. Besides that, calcium hypochlorite is a very advantageous solution and is often used for the treatment of water tanks.

Finally, sodium hypochlorite or bleach is a very effective and less dangerous chlorine derivative than chlorine gas. With various concentrations, sodium hypochlorite offers low-cost disinfection with little risk associated with its handling. In addition, because of its various concentrations and its liquid state, it is relatively easy to better dose the necessary quantities.

In short, regardless of the chlorine derivative chosen to disinfect a purification system, the oxidizing agent must be added to the water in order to do its job. Then, mixing it with water will cause a chemical reaction creating hypochlorous acid (HOCl) and hypochlorite ions (OCl-). The solution of HOCl + OCl- is what makes chlorine a product with a high oxidation potential and provides effective disinfection. To ensure optimal disinfection with chlorine, it is important to calculate the dosage carefully. To be effective, chlorination must be adjusted according to the type and quantity of contaminants found in the water. Furthermore, the necessary dosage varies according to the type of chlorine used. For example, the following table illustrates the concentrations necessary for sodium hypochlorite (bleach).


Quantity of water to be treated (L)

Chlorine concentration required




Chlorine (mL)

Chlorine (mL)

Chlorine (mL)





















10 000




16 000




20 000




30 000






The benefits of choosing chlorination are varied, it is a relatively inexpensive and proven solution. It has demonstrated effectiveness against the spread of bacteria, removal of certain heavy metals, control of algae and can remove odor, taste and color from water. Using chlorine to disinfect a pharmaceutical water purification system is a viable, effective, and simple option.



Ozone (O3) is a highly reactive gas that consists of three oxygen atoms. Naturally occurring, man-made and highly reactive, O3 cannot be stored and poses health risks as it is a toxic gas. Because it is toxic and highly reactive, it reacts rapidly with hydrocarbons and thus ensures an efficient destruction of biofilms, microbes, and organic residues. In other words, O3 disinfects, controls endotoxins, prevents biofilm formation and sanitizes water.

Recognized as the most effective commercial oxidizer, tests have shown a disinfection power nearly 3000 times greater than chlorine. A concentration of 2PPM of ozone for 30 minutes established a disinfection efficiency of 99.9999% of contaminants. Hence, this technology is very popular in the pharmaceutical, cosmetic and semiconductor industries.

Ozonation is a treatment that generally needs to be performed once or twice a week. To do so, ozonation requires an ozone generator that must be integrated into the purification system. Once integrated into the system, the ozone generator will automate the disinfection cycles. Again, since ozone is a toxic gas, generators are very often accompanied by an ozone destructor which, most of the time, is a UV disinfection. In short, there are several ways to generate ozone, the two most used are corona discharge and electrolytic generation.

Electrolytic Ozone

Electrolytic ozone is created through a system of electrodes and the generation of a high voltage between them. When a liquid loaded with oxygen passes between the electrodes and the current is sent between these two metallic components, ozone is created.

Often used for relatively small systems, this type of generator is unique in that it generates ozone directly from water. Therefore, this technique requires special insulation and is subject to contamination since the generator is in direct contact with the treated water.



Ozone by Corona Discharge

For corona discharge ozone, a controlled high voltage current must be discharged between refractory electrodes within an oxygen containing gas.

 Once this step is completed, the ozone created is automatically injected into the water by the generator. The advantage of this technology lies in the optimal control of ozone concentrations. In addition, the corona discharge system requires less maintenance since it is not in direct contact with the water.



Benefits of Ozone

First, ozone is a product that must be created on site, which eliminates the transportation of chemicals and their handling. Thus, the entire disinfection process can be automated. Secondly, O3 offers fast and effective action against bacteria and viruses while decreasing the chances of spreading unwanted by-products.

From an environmental point of view, ozone disinfection offers interesting advantages since the organic matter is oxidized with oxygen rather than with another molecule. In fact, several studies have shown that ozonation significantly reduces the concentrations of pharmaceuticals and personal care products, mitigates the effects of endocrine disruptors, and reduces the toxicity of the treated effluent.


The best disinfection for you

There are many criteria to consider when selecting a disinfection method for your water purification system. Among these criteria, it is imperative to consider government standards, the purity of the water required, the ROI, the contaminants present in the make-up water and the associated risks.

Since it is difficult, if not impossible, to know all the technologies available and this article is just the tip of the iceberg, we recommend that you seek the advice of a team of experts to help you make the right choice and identify the best solution for you. In the meantime, check out this article to learn more about how to prevent bacterial contamination of pharmaceutical water.

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