07/26/2021 | Municipal Wastewater | 8 MINUTE READ

Wastewater Chlorination: Everything You Need To Know

wastewater chlorination

Whenever you do laundry or take a bath, the water that’s created from these everyday processes is referred to as wastewater. Residential wastewater is commonly generated through processes like washing dishes and flushing toilets. As for commercial wastewater, it can be generated from the processes that occur at auto repair shops, beauty salons, furniture refinishing stores, and similar facilities. The wastewater that’s generated from commercial settings is typically more hazardous than residential wastewater because of the chemicals that these facilities tend to use.

Wastewater contains a high level of contaminants, which means that the water needs to be treated if it’s going to be sent back into the environment or used for other purposes. Once municipal wastewater has been properly disinfected, it should be safe to use for potable water supplies. Likely the most dangerous contaminants that can be found in untreated wastewater include microorganisms that can bring about harmful waterborne diseases.

One method that’s used to treat wastewater is chlorination, which is known to be particularly effective at removing viruses, protozoa, and bacteria from the wastewater. Even though chlorination is widely used for its ability to get rid of most pathogenic organisms more effectively than other treatment methods, it can also remove most other contaminants that are found in water. As mentioned previously, chlorination can be important during wastewater treatment if you want to eliminate the pathogenic organisms that can cause waterborne illnesses.

In the event that wastewater is discharged from a treatment facility before chlorination is used, human exposure to pathogens could occur via swimming or drinking water. The pathogens that are most commonly present in wastewater include mycobacteria, hookworm ova, Salmonella, E. coli, and Streptococcus. Each of these microorganisms can cause people to become sick following exposure. This article offers a comprehensive overview of wastewater chlorination.

Dechlorination: Why It Matters

While chlorination is an effective technique that can be used for wastewater treatment, there are also times when dechlorination should be used. Nearly every wastewater treatment facility uses chlorination to disinfect wastewater before the water is sent back out into the environment. The primary goal of chlorination is to disinfect the wastewater and remove any harmful pathogens that are present in the water. Once the wastewater has been properly treated, it can flow naturally into rivers, streams, and oceans without issue.

When a facility performs the chlorination technique, an ample amount of chlorine is placed in the wastewater to oxidize the contaminants within. This process ends up creating byproducts that are relatively harmful and will be present in the treated water until further treatment occurs. Dechlorination is a process designed specifically to get rid of the chlorination byproducts that could cause health issues if consumed in high amounts. Once the dechlorination process has occurred, the water should be completely disinfected and safe to drink.

The Disinfectant in Wastewater: Chlorine

dechlorination for wastewaterBefore you decide to use chlorine to disinfect wastewater, you should better understand the benefits that this treatment method offers. Along with removing any pathogens that can be found in the wastewater, chlorine is also able to:

  • Perform foul air scrubbing
  • Destroy phenols and cyanides
  • Control activated sludge bulking
  • Stabilize waste activated sludge before disposal occurs
  • Remove ammonia from water
  • Control filter flies and foaming
  • Assist in removing grease and scum from the water
  • Mitigate odors and keep septicity at bay
  • Disinfect the water

Keep in mind that nearly all contaminants must be removed from wastewater before it can be deemed as having been disinfected. There are many industries that produce industrial wastewater and must perform wastewater treatment. For instance, metal finishing operations are known to produce a slurry that consists of metals that have been dissolved in liquid. Some of the metals that can be found in metal finishing waste include nickel, copper, aluminum, and zinc.

A sizable amount of wastewater is also produced by chemical manufacturing processes. There are strict environmental regulations in place to make sure that chemical industrial facilities treat all of their wastewater effluents. The pollutants that are typically discharged at petrochemical plants and petroleum refineries include grease, oil, suspended solids, phenols, and ammonia. Some of the other industries that are known to produce high amounts of wastewater include:

  • Power plants
  • Oil and gas fracking processes
  • Steel and iron production
  • Mining
  • Food processing

Safe Handling and Using Chlorine

using chlorine for wastewaterWhen you’re preparing to use chlorine for wastewater treatment purposes, it’s important that you understand how to safely handle and use this substance. You can use chlorine for wastewater disinfection as a chlorinated compound or elemental chlorine, the latter of which is in a gaseous state upon use. If you want to use the more affordable treatment solution, elemental chlorine is typically less expensive than a chlorinated compound.

If you decide to purchase a chlorinated compound, it’s possible to select calcium hypochlorite or sodium hypochlorite to treat your wastewater. Keep in mind that calcium hypochlorite is a solid compound. On the other hand, the sodium hypochlorite solution comes in a liquid state. If the water is weakly buffered, elemental chlorine will invariably cause pH levels to decrease. Using hypochlorites can increase pH levels by a slight amount.

It’s important to understand that the effectiveness of chlorine disinfection depends somewhat on the water’s pH levels. The best and most effective disinfection occurs when the water is at a lower pH. Chlorine is created by applying electricity to brine solutions, which refers to a mixture of water and salt. If you want to make sure that you handle chlorine safely, you should know that this chemical can be hazardous to your health if not handled correctly. When you are working with chlorine, make sure that you:

  • Don’t attempt to combine different types of chlorine
  • Don’t inhale any of the fumes
  • Don’t contact chlorine with your bare hands
  • Don’t combine chlorine with additional substances

It’s also important that you store chlorine properly to avoid any hazardous situations. Some safety tips for chlorine storage include:

  • Make sure that the chlorine you use remains in its original casing
  • Keep this chemical away from pets and children
  • Keep chlorine away from other chemicals that are considered to be flammable
  • Follow the manufacturer’s instructions for storage

Chlorine is typically used to disinfect pool water because of how safe it typically is when placed in water. However, there are still some health concerns that you should be on the lookout for if you happen to come into contact with chlorine. These health effects include:

  • Hair discoloration
  • Issues with your breathing, which could lead to asthma
  • Absorption into your skin, which may eventually cause long-term health issues
  • Eye irritation
  • Skin irritation

Chlorine in Drinking Water

Chlorine is highly effective at treating drinking water and making sure that this water is perfectly safe to consume. Because of how effective chlorine is at getting rid of harmful pathogens in wastewater, chlorination has been the primary disinfection method used for drinking water treatment over the past century. Even though chlorination was initially used for the treatment of drinking water, the effectiveness of this treatment method pushed facilities to start using it to disinfect all forms of wastewater.

It’s important to understand that waterborne diseases were very common up until the early 20th century. While earlier treatment methods were able to get rid of many contaminants that were present in drinking water, chlorine was the only solution that proved to be effective at reducing pathogens in the water supply. Since chlorination was widely adopted throughout the U.S., waterborne illnesses like typhoid, dysentery, and cholera have all but disappeared.

Along with being more effective at treating drinking water when compared to other disinfection techniques, chlorine is more efficient, more affordable, and considerably easier to use than alternatives.

Even though chlorination is primarily used because of its ability to get rid of pathogens, it has also proven to be effective at reducing the amount of lead and iron that can be found in the water. Both iron and lead are known to create taste issues with water, which is why it’s recommended that you use a treatment that can eliminate these contaminants. Using chlorination to disinfect drinking water also helps to ensure that some residual disinfectant remains in the water from the time it leaves the treatment facility and ends up at the consumer’s tap.

Wastewater chlorination is a great disinfecting solution that offers benefits that can’t be found with other treatments. While ozone and ultraviolet disinfection provide some notable advantages in certain areas, chlorination is a cost-effective and well-established technology that practically anyone can use. Now that you know the benefits of chlorination and how to safely handle chlorine, you should have the tools you need to start treating wastewater at your facility.

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Posted by Dominic O'Donnell on July 26, 2021

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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